Offshore drilling units

Technical report on jack up

By:

Majid hamedinia

First version April2009

Introduction

Natural oil leaks have been present since before the days of dinosaurs about 200 million years ago.

Lighter oils evaporate in air leaving behind the heavier oils in “tar pits”. People have used this

naturally occurring oil since the beginning of recorded human history. Oil can also be made from

animal fat, and it is not always clear whether mention of oil in ancient records refers to oil from the

ground or from animals.

Ancient Greek texts describe how they would pour oil onto the sea to set fire to their enemies'

fleets. The Bible refers to a thick form of oil called "Pitch" which was used to waterproof Noah's

ark and the baby Moses' basket. The American Indians also used pitch to waterproof canoes and

medicines. These examples are probably uses of oil from the ground.

The word “Petroleum” comes from the Greek word for rock and the Latin for oil or fat. It literally

means “oil that comes from rock”. Petra / petros (Greek) = rockoleum, (Latin) = oil / fat Crude oil

was pumped from the ground in Sichuan, China, 2500 years ago, but the history of oil wells as we

know them today is much younger.

A brief history starting in 347 A.D: 347 Oil wells are drilled in China up to 800 feet deep using bits

attached to bamboo poles. 1264 Mining of natural oil seeps in medieval Persia is witnessed by

Marco Polo on his travels through Baku. 1500’s Seep oil collected in the Carpathian Mountains of

Poland is used to light street lamps. 1594 Oil wells are hand dug at Baku, Persia up to 35 meters

(115 feet) deep. 1735 Oil sands are mined and the oil extracted at Pechelbronn field in Alsace,

France. 1815 Oil is produced in United States as an undesirable by-product from brine wells in

Pennsylvania. 1848 First modern oil well is drilled in Asia, on the Aspheron Peninsula north-east of

Baku, by Russian engineer F.N. Semyenov. 1854 First oil wells in Europe are drilled 30- to 50-

meters deep at Bóbrka, Poland by Ignacy Lukasiewicz. Oil historians in the USA give credit for the

first modern commercial oil well to Colonel Edwin L. Drake. His well reached a depth of 22m (72-

ft). It was drilled in “Oil Creek” near the town of Titusville, slightly east of Pittsburgh,

Pennsylvania, USA and started producing oil on August 28, 1859. There were no automobiles in

those days; the main market for petroleum was for medicine. It was called Rock Oil and sold for

about $40 a barrel, which is about the same as a barrel of oil costs today, so it would have been

worth a lot of money in 1859. There are several other claims for “the first oil well”, including a well

drilled in 1858 in Wietze, Germany.

Iranian called it "Well Number One". A sign proudly proclaims the spot where the first middle-

eastern oil was discovered 100 years ago. The oil derrick is still there - it produced oil for 70 years.

The town itself - Masjid e Suleiman - in south west Iran, is still an oil town. The countryside is

criss-crossed with the pipelines that bring oil from each wellhead to the refinery or the export

terminal. But much else has changed. For nearly 50 years the Iranian oil industry was controlled by

the British Anglo-Persian Oil company. You can still see the names of British companies on some

of the older plant. But the British only paid $75,000 (£40,000) for the original 60-year concession -

and a small share of the profits. To this day, that is the source of enormous bitterness in Iran. British

presence "No fair British person can be proud of that part of the history of the UK in Iran".

Iran still provides nearly 5% of the world's oil needs. It is strange then, that an industry of such

global importance should be so isolated.

The first offshore oil well was in the bayous (swamps) of Louisiana, USA during the 1950s. The

first drilling in open sea was done in 1955 for Shell Oil in the Gulf of Mexico just south of New

Orleans. This used a barge with a drill rig attached named “Mr. Charlie", which continued to drill in

the Gulf of Mexico for 32 years. Whit

How to exploit

Drilling for oil requires extensive planning and a good amount of capital to invest. The project will

require you to work with contractors, financiers, land owners, geologists and engineers. All

activities for exploitation of oil can be mentioned in some steps.

The oil is found in the reservoir rock under the ground several hundred meters down. The most

conventional conformation in which oil is found is called the folding movement where the earth has

moved inward to form an upward fold. To find oil, geologists are hired who are experts in analyzing

surface texture, features, soil types and core samples. The geologists also employ different high

technology instruments for example, magnetometer, gravity meters, seismic instruments using

shock wave technology, and satellite pictures to find flowing oil under the rocks of the Earth.

When geologists determine a good site it is surveyed for boundaries and environmental studies.

Lease is signed and the legal right to the land is obtained from the local authorities.

A reserve pit is made for the debris coming out from the drilling. The land is prepared for the rig

and cleared off of trees and vegetations. Several holes are made for the rig to fit in. A conductor

pipe is made which is the top portion of the main hole and is larger in diameter than the rest of the

hole.

Once the oil rig is installed, it is connected with several other components. These components

guarantee the normal functioning of the equipment and safety in case of unexpected pressure release

from the bottom of the soil. The hole is dug and casing is installed around it to prevent it from

collapsing.

When the oil sand is reached from the reservoir rock, it is analyzed for core sampling, pressure and

quality of reservoir rock. A device called a perforating gun is inserted to extract the oil from the

well, once the desired depth is reached. When the oil starts flowing in the well, the rig is removed

and the oil production equipment is installed to extract the oil.

But what we wrote was about drilling in land, Drilling for oil in the ocean is one of the greatest

technological breakthroughs in recent decades, and many new techniques have been developed to

profit from the abundance of oil underneath the ocean floor. While drilling for oil has been around

for hundreds of years in one form or another, the effective extraction of petroleum from beneath the

sea floor did not surface until the last forty years. Whit regard to oil place, land or sea, there are

different type of drilling rig. On the continuation of this article we will write about offshore drilling

individually.

Types of Drilling Rigs

A drilling rig is a structure housing equipment used to drill for water, oil, natural gas from

underground reservoirs or to obtain mineral core samples. The term can refer to a land-based rig, a

marine-based structure commonly called an 'offshore rig' or a structure that drills oil wells called an

'oil rig'. The term correctly refers to the equipment that drills oil wells or extracts mineral samples,

including the rig derrick (which looks like a metal frame tower).

Sometimes a drilling rig is also used to complete (prepare for production) an oil well. However, the

rig itself is not involved with the extraction of the oil; its primary function is to make a hole in the

ground so that the oil can be produced. Laypeople may refer to the structure which sits on top

offshore wells as a 'rig', but this is not correct. The correct name for the structure in a marine

environment is platform. A structure upon which wells produce is a production platform. A floating

vessel upon which a drilling rig sits is a floating rig or semi-submersible rig because the whole

purpose of the structure is for drilling. Drilling rigs can be small and portable such as those used in

mineral exploration drilling, or huge, capable of drilling through thousands of meters of the Earth's

crust; large "mud pumps" are used to circulate drilling mud (slurry) through the drill bit and the

casing, for cooling and removing the "cuttings" whilst a well is drilled; hoists in the rig can lift

thousands of tons of pipe; other equipment can force acid or sand into reservoirs to facilitate

extraction of the oil or mineral sample; and permanent living accommodation and catering for crews

which may be greater than a hundred people in number. Marine rigs may operate many hundreds of

miles or kilometers offshore with infrequent crew rotation. With regard to the below picture we can

understand there are different type of rigs. But in this article we want to focus on offshore rig and

jack up individually.

All type of rigs (land and offshore rigs).1

History

Until the advent of internal combustion engines in the late 19th century, the primary method for

drilling rock involved muscle power be it human or animal. Rods were turned by hand, using

clamps attached to the rod. The rope and drop method invented in China utilized a steel rod or

piston raised and dropped vertically via a rope. Mechanized versions of this persisted until about

1970, utilizing a cam to rapidly raise and drop what, by then, was a steel cable.

In the 1970s, outside of the oil and gas industry, roller bits utilizing mud circulation were replaced

by the first efficient pneumatic reciprocating piston RC drills, and became essentially obsolete for

the majority of shallow drilling, and are now only used in certain situations where rocks preclude

other methods. RC drilling proved much faster and efficient, and continues to improve with better

metallurgy deriving harder, more durable bits, and compressors delivering higher air pressures at

higher volumes, enabling deeper and faster penetration. Diamond drilling has remained essentially

unchanged since its inception.

Drilling rig classification

There are many types and designs of drilling rigs, depending on their purpose and improvements;

many drilling rigs are capable of switching or combining different drilling technologies.

1) By power used

Electric - rig is connected to a power grid usually produced by its own generators,

Mechanic - rig produces power with its own (diesel) engines, hydraulic - most movements are done

with hydraulic power, pneumatic - pressured air is used to generate small scale movements

2) By pipe used

Cable - a cable is used to slam the bit on the rock (used for small geotechnical wells)

Conventional - uses drill pipes

Coil tubing - uses a giant coil of tube and a down hole drilling motor

3) By height

Single - can drill only single drill pipes, has no vertical pipe racks (most small drilling rigs)

Double - can store double pipe stands in the pipe rack

Triple - can store stands composed of three pipes in the pipe rack (most large drilling rigs)

Quad - can store stands composed of four pipes in the pipe rack

4) By method of rotation

No rotation (most service rigs)

Rotary table - rotation is achieved by turning a square pipe (the Kelly) at drill floor level.

Top-drive - rotation and circulation is done at the top of the drill string, on a motor that moves along

the derrick.

5) By position of derrick

Conventional - derrick is vertical

Slant - derrick is at an angle (this is used to achieve deviation without an expensive down hole

motor)

Offshore Drilling rigs

Drilling rigs are designed to meet specific operation requirement, therefore, different rigs have

different capabilities. All offshore rigs perform the basic function of drilling a hole or well in

submerged lands that means of rotary drilling. This procedure provides the method of exploring for

or producing oil and gas from earth formation. Offshore drilling rigs can be classified into two

major groups: floating and stationary.

Floating rigs: floating rigs are those rigs which rely upon an anchoring or positioning system to

keep them over the drilling location. These rigs are usually self propelled and normally used for

exploratory drilling. We can assume drill ships and semi submersibles in this type of rigs.

Drill ship:

These look like ordinary ships but have a derrick on top which drills through a hole in the

hull. Drill ships are either anchored or positioned with computer-controlled propellers

along the hull which continually correct the ships drift. On the other word, Drill ship is a

maritime vessel that has been fitted with drilling apparatus. It is most often used for

exploratory drilling of new oil or gas wells in deep water but can also be used for

scientific drilling. It is often built on a modified tanker hull and outfitted with a dynamic

positioning system to maintain its position over the well. The two basic type of drill ships

are the barge type and the self-propelled type, or non-self-propelled drill ships must be

towed into position above drilling site. Self-propelled type drill ships are capable of

movement under their own power and do not require towing. Drill ships employ two basic

method of station keeping to maintain their position above drilling sites. Drill ships that

use a conventional anchoring system utilized a series of anchor that fan out from the bow

and stern of the ship and are set into the sea floor.

Drill ships that are dynamically positioned keep their position above the drill sites by

using bow and stern thrusters that are computer controlled.

The latest drill ship of Samsung co. 2

Drilling unit with barge type.3

Semi submersibles:

Semis, as they are called, are also used to drill single exploratory wells. The majority of semis are

towed to their drilling location, although some of the more recent models are self –propelled. The

basic deck configurations range from triangular to pentagonal and utilized anywhere from three to

over ten legs for support. The legs are attached to hulls or pontoons that can be flooded. The

primary advantage of semis over drill ship is their height degree of stability in rough weather. Semis

utilized a spread anchoring system of radial space anchors to hold their position. The spread of

anchors is dependent upon anticipated wind and sea condition. Then, these types have hulls,

columns and pontoons, for sufficient buoyancy to cause the structure to float, but of weight

sufficient to keep the structure upright. Semi-submersible can be moved from place to place; can be

ballasted up or down by altering the amount of flooding in buoyancy tanks; they are generally

anchored by combinations of chain, wire rope and/or polyester rope during drilling and/or

production operations, though they can also be kept in place by the use of dynamic positioning.

Semi-submersibles can be used in water depths from 200 to 10,000 feet (60 to 3,050 m).

Diagram of Semi submersibles.4

Semi submersibles.5

As mentioned above all type of floating rigs use anchor for positioning and keeping their locations.

On the continuation of this part we will present anchor and the most important topics related to that.

Anchor:

Device cast overboard to secure a ship, boat, or other floating object by means of weight, friction,

or hooks called anchor. In ancient times an anchor was often merely a large stone, a bag or basket

of stones, a bag of sand, or, as with the Egyptians, a lead-weighted log. The Greeks are credited

with the first use of iron anchors, while the Romans had metal devices with arms similar to modern

anchors. The ordinary modern anchor consists of:

The shank is the stem of the anchor in which direction is pulled to set (bury) the anchor.

The crown connects the various parts of the modern anchor.

The stock turns the anchor into an attitude that enables the flukes to dig into the sea bed.

The tripping ring is used for the optional tripping line: by pulling the tripping line, the

anchor will break out.

The flukes will be buried into the seabed. The very tip of a fluke is sometimes called the bill.

In the below picture, anchors parts are showed.

Semi submersibles.6

Anchor type:

There is some most important kind of anchor:

Mushroom type: The mushroom anchor is suitable where the seabed is composed of fine sand

or soft mud. It is shaped like a mushroom. It is a bit better than a simple weight, but not as

good as a temporary anchor design of the same weight. This type of anchor can be as light as

10 pounds or as heavy as several tons. They must be allowed to set by sinking over a long

time.

Mushroom anchor.7

Hall type: The stockless anchor which was patented in England in 1821 came into wide use

principally because of its ease of handling and stowing. The crown, arms, and flukes of a

stockless anchor are cast in one piece and can pivot slightly from side to side on the shank.

The flukes are long and heavy, and have projecting shoulders at their base that catch on the

seabed. As more drag is exerted, the shoulders force the flukes downward into the bottom.

Stockless anchors have replaced the older stock anchor on most of the large ships of the

world.

Hall type anchor.8

Several other types of anchors are in common use. Lightweight, Danforth, and plow anchors

have long, sharp flukes that pivot around a stock at the bottom of the shank and bury

themselves deeply into the bottom; these anchors are generally used for yachts and other

small craft.

How to choose an anchor:

To select an anchor, choice on three points will be done:

1- PRICE: Your anchor is your best insurance and, like your insurance, it seems expensive

only before the accident occurs. When the weather deteriorates and your boat drags towards

the rocks, it is too late to regret the tens of pounds saved on the purchase price. If your boat

is tossed on the shore, then the cost may well be thousands of pounds. Security and quiet

nights at anchor don't have a price.

2- WEIGHT: The weight of your anchor has almost no relation to the holding. Holding is

related to :

The stability of your anchor

Its surface area

The shape of the holding surface

All recent tests have proved that aluminum anchors have the same holding as steel anchors of the

same size (Practical Sailor, Bateaux, Voiles magazine.)

However, weight is very important for the penetration of the anchor. If you choose a light (i.e.

aluminum) anchor, then favor stable models, those with a penetrating angle like a chisel and those

with a heavily weighted tip.

3- EFFICIENCY: Efficiency of an anchor is a function of both penetration and holding.

To ensure good holding, an anchor must first penetrate regardless of the sea bottom type, as quickly

and deeply as possible. Once set, the anchor must not break free regardless of weather conditions.

This is a function of anchor stability and the shape and size of the holding surface.

Stationary rigs:

Stationary drilling rigs, as defined by their name, are affixed to the ocean floor by some type of

legs. Some stationary rigs are moveable; however, during drilling operation, they don’t encounter

the oceans movement because their drilling platforms are positioned above the water line.

Stationary rigs are used both for exploration and production of oil and gas fields. There are three

important type of stationary rigs; fixed platform, platform tender and jack up. In this article ewe will

engage in jack up more than the two others.

Fixed platform:

A fixed Platform is a type of offshore platform used for the production of oil or gas. These

platforms are built on concrete and/or steel legs anchored directly onto the seabed, supporting a

deck with space for drilling rigs, production facilities and crew quarters. Such platforms are, by

virtue of their immobility, designed for very long term use. Various types of structure are used, steel

jacket, concrete caisson, floating steel and even floating concrete. Steel jackets are vertical sections

made of tubular steel members, and are usually piled into the seabed. Concrete caisson structures,

pioneered by the Condeep concept, often have in-built oil storage in tanks below the sea surface and

these tanks were often used as a flotation capability, allowing them to be built close to shore

(Norwegian fjords and Scottish firths are popular because they are sheltered and deep enough) and

then floated to their final position where they are sunk to the seabed. Fixed platforms are

economically feasible for installation in water depths up to about 1,700 feet (520 m).

ChevronTexaco's Genesis.9

Courtesy Statoil platform.10

Platform tenders:

Platform tenders, as the name implies, serve to support a fixed platform drilling operation. Unlike a

full scale platform operation, the support equipment such as the mud pumps, bulk material storage

container and crew quarter are located aboard the tender rather than mounted onboard the platform.

Physically connection between the platform and the tender is maintained by means of bow ramp, or

a thing similar to that. Tubular goods such as drill pipes and casing are stored aboard the tender and

transferred as needed to the plat form. Pedestal cranes are provided aboard the tender for this

purpose as well as for personal transfer.

Diagram showing basic area of a platform tender.11

Gas platform and tender in Mobile Bay.12

Jack up:

If you glance at statistical report, you can find about 30% of oil and gas wells hone been dug by

jack up, and this clearers importance of jack up drilling rigs and their influence.

Most of the world’s offshore drilling in water depths up to 120m is performed from selfelevating

mobile units, commonly known as jack-ups. Typical units consist of a buoyant triangular platform

resting on three independent truss-work legs, with the weight of the deck and equipment more or

less equally distributed. A rack and pinion system is used to jack the legs up and down through the

deck. Jack-ups are towed to site floating on the hull with the legs elevated out of the water. On

location, the legs are lowered to the sea-bed, where they continue to be jacked until adequate

bearing capacity exists for the hull to climb out of the water. The foundations are then pre-loaded by

pumping sea-water into ballast tanks in the hull. This ‘proof tests’ the foundations by exposing

them to a larger vertical load than would be expected during service. The ballast tanks are emptied

before operations on the jack-up begin. It is usual for the total combined pre-load (i.e. jack-up mass

and sea-water) to be about double the mass of the jack-up.

A Jack Up is an offshore structure composed of a hull, legs and a lifting system that allows it to be

towed to a site, lower its legs into the seabed and elevate its hull to provide a stable work deck

capable of withstanding the environmental loads.

A typical modern drilling Jack Up is capable of working in harsh environments (Wave Heights up

to 80 ft, Wind Speeds in excess of 100 knots) in water depths up to 500 feet. Because Jack Ups are

supported by the seabed, they are preloaded when they first arrive at a site to simulate the maximum

expected leg loads and ensure that, after they are Jacked to full air gap and experience operating and

environmental loads, the supporting soil will provide a reliable foundation.

A jack up rig under way.13

PURPOSE AND DISCLAIMER

Jack up unit is complex structures used offshore in many modes of operation. When using a

particular unit at a given site, it is important to be aware and understand the basics behind the

different designs under different conditions. The focus of this article is a simplified discussion of

the various sensitivities of Jack Ups while in the different modes of operation. It is hoped that by

increasing the understanding of how Jack Ups work and behave as well as the sources of the loads

acting on them, those making decisions with limited information will be better equipped to respond

to incidents and reduce their occurrence and/or consequences. Though there are many variations in

design and purposes for Jack Ups, this article focuses many of these discussions on three-legged

Units used for drilling the article starts by presenting some background and discussions of the

basics of Jack Up components analyses. This is followed by sections on Jack up Components and

Configurations, modes of operation, differences between Class approval and site specific

assessment, basic analysis, and a discussion of competing aspects of Jack up design.

History of jack up

The earliest reference to a jack-up platform is in the description of a United States patent

application filed by Samuel Lewis in 1869 (Veldman and Lagers, 1997). It wasn’t until 85 years

later in 1954 that Delong McDermott No. 1 became the first unit to utilize the jack-up principle for

offshore drilling. Delong McDermott No. 1 was a conversion of one of the successful ‘Delong

Docks’: a pontoon with a number of tubular legs which could be moved up and down through cut-

outs in the pontoon. The Delong Docks, which were mostly used as mobile wharves for industrial

purposes during the 1940s, could be towed into location with their legs drawn up. Once in position

their legs could be lowered and the pontoon elevated off the water using the same principle as the

modern jack-up. Interestingly, Delong Docks were used in World War II as mobile docks by the

United States Army after the invasion of Normandy and before the major harbours of Western

Europe were liberated (Veldman and Lagers, 1997). Like many of the early jack-ups to follow,

Delong McDermott No. 1 resembled a standard drilling barge with attached legs and jacks, which

were often many in numbers. In 1956 R.G. LeTourneau, a former entrepreneur in earthmoving

equipment (Ackland, 1949), revolutionised the design of jack-ups by reducing the number of legs to

three (Stiff et al., 1997). Another innovative design change was the electrically driven rack and

pinion jacking system which allowed for continuous motion in any jacking operation. This replaced

‘gripper’ jacks where slippage often occurred on the smooth leg surface (Veldman and Lagers,

1997). Both revolutionary features are common on today’s rigs. Zepata’s “Scorpian”, used in water

depths up to 25 m in the Gulf of Mexico, was the first of many operated by the company Marathon

LeTourneau. They dominated early jack-up design during the 1960s and 1970s with rigs of

increasing size. Since their first employment, jack-ups have continued to be used in deeper waters

(Carlsen et al., 1986). Other companies, including Bethlehem, Friede and Goldman,

MarineStructures Consultants and Mitsui have contributed to the rise in water depth capacity

(Veldman and Lagers, 1997). This development is continuing with some of the largest units being

used in about 120m of water in the relatively harsh North Sea environment (Hambly and Nicholson,

1991; Veldman and Lagers, 1997). Furthermore, jack-ups are now operating for extended periods at

one location, often in the role of a production unit (Bennett and Sharples, 1987). An example of the

long-term use of jack-ups is in the Siri marginal field development in the Danish sector of the North

Sea. A purpose built jack-up is being used in 60 m water depths as a production platform with an

expected life of ten years (Baerheim et al., 1997). A further example is the Shearwater

development, where jack-up drilling is planned to continue for two and a half years at a 90 m water

depth in the Northern North Sea (Offshore Technology, 1999).

background

Jack up Unit has been a part of the Offshore Oil Industry exploration fleet since the 1950’s. They

have been used for exploration drilling, tender assisted drilling, production, accommodation, and

work/maintenance platforms. As with every innovative technology, Jack Up Units have been used

to their operational and design limitations. These limitations include deck load carrying limits when

afloat, load carrying capabilities when elevated, environmental limits, drilling limits, and soil

(foundation) limits. The reasons for pushing these limits include the desire to explore deeper waters,

deeper reservoirs in harsher environments, and in areas where soils and foundations may be

challenging or even unstable. Into this area of expanding Jack up Units’ capabilities, Industry

Groups, Classification Societies, and Flag States have involved themselves in an attempt to

Regulate, Codify, and Unify the criteria used to gauge a Jack up Unit’s capabilities. Without a

thorough knowledge of the background of these Regulatory efforts and the science that these efforts

rely upon, the average Offshore Industry professional is given practically no useful tools when it

comes time to assess, understand, and select a Jack Up Unit to fulfill a particular task or Mission

Statement. An often time, a thorough understanding of Jack up unit capabilities and “sensitivities”

prevents or minimizes the consequences of unexpected “incidents.” This section of article is an

attempt to assist such individual in understanding the Regulations, science and engineering

principles behind a Jack up Unit’s design and to assist that individual in answering the following

questions:

What are the components of a Jack up Unit and what are their functions?

What are the relative pros and cons of different types of Jack ups and their features?

How does the arrangement of a Jack Up affect its function and capability?

What are the loads on a Jack Up, what impact do they have, and how are they

evaluated?

Who are the parties involved in the Jack up from design through operation, and what

are their roles?

How do I select a suitable Jack up unit for my particular application?

Some useful definition

Some simple definitions will be useful and necessary, before of jack up rigs topic.

Gin Pole - An “A” frame structure located at the top of standard derricks used to list and

lower the crown block into position.

Crown Block - A series of sheaves affixed in the top of the derrick used to change the

direction of pull from the draw works to the traveling block.

Derrick - Vertical structure that allows vertical clearance and strength to raise and lower

the drill string. This structure with-stands two types of loading: compressive loading and

wind loading.

Stand - A stand generally consists of two to four joints of made-up drill pipe. The stand is

generally used when running or pulling the drill string in and out of the hole.

Monkey board - (Stabbing board) the platform on which the derrick man works when

tripping pipe.

Racking Fingers - Fingers or members where the stands are racked and secured while

tripping pipe.

“A” Frame - The “A” frame structure on a jackknife used to raise and lower the mast. It

also supports the derrick in the raised position.

Bull line and Sheaves - The large line and sheaves located on the “A” frame of a jackknife

used to raise and lower the derrick.

Traveling Block - The block and tackle which is rigged with the crown block by multiples

of drilling line strung between the crown block and the traveling block.

Swivel - That part of the drill sting which connects the rotary hose to the drill string and

allows circulation and rotation at the same time.

Kelly - The square or hexagonal member at the upper most part of the drill string

(immediately below the swivel) that passes through a properly fitting bushing known as the

Kelly bushing or drive bushing. The drive bushing transmits rotary motion to the kelly

which results in the turning of the drill string.

Kelly Bushing/Drive Bushing - That bushing which fits inside the rotary bushing and

transmits rotary torque to the Kelly.

Rotary Bushing - The bushing that fits inside of the rotary table opening. This is where the

drill pipe and collar slips seat when the drill string is suspended from the rotary table for

connections or tripping pipe.

Rotary - Transmits the rotary motion or torque from the power source to the drive bushing.

Kelly Cock - Safety valves located above and/or below the Kelly. These valves are of a

ball type and must be manually operated. Their primary purpose is to prevent flow up the

drill string in case of emergencies. A third Kelly cock is generally kept on the drill floor to

be used in the drill string in the event flow up the drill string occurs while making a

connection or tripping pipe. (Federal leases, USGS, requires two Kelly cock valves- above

and below the Kelly- and a third one on the drill floor in the opened position.) A secondary

use of the Kelly cock valve below the Kelly is to prevent the loss of mud from the Kelly

while making a connection. This should be discouraged to prevent wear on the Kelly cock

valve.

Inside POB Valve - This valve is also used to prevent flow up the drill string when the well

kicks and a connection or tripping operations are under way. This valve operates like a

check valve and is always kept in open position on the rig floor. This valve is required to

be on the rig floor in the open position for Federal leases.

Kelly Saver Sub - A sub located blow the lower kelly cock valve. The function of this sub

is to prevent wear on the kelly’s threads and to centralize the kelly by means of a rubber

protector, thus preventing wear on the kelly’s hexagonal or square shape.

Elevators - The elevators are used for latching on to the tool joint or lift sub of the drill

pipe or drill collars. This enables the lifting and lowering of the drill string while making a

trip. The elevators are connected to the hoisting system (traveling block) by means of bails.

Bails - The bails connect the traveling block and elevators. They are solid steel bars with

eyes at both ends

Hook - The hook is located beneath the traveling block. This device is used to pick up and

secure the swivel and kelly.

Slips - Latch around the drill pipe and seat in the rotary bushing in the rotary table. The

slips support and transmit the weight of the drill string to the rotary table while making a

connection or tripping pipe.

Draw works - The principal parts of the draw works are the drum, the drum brakes,

transmission, and cathead. The principal function is to convert the power source into a

hoisting operation and provide braking capacity to stop and sustain the weights imposed

when lowering or raising the drill string.

A. the drum is housed in the draw works and transmits the torque required for

hoisting and braking. It is also used as a hoisting device for heavy equipment on the

drill floor.

B. This is done by wrapping the catline (catline is generally made of rope and is

connected to a piece of chain used to tie on to equipment) around the lifting

head. The number of turns of rope on the head and the tension provided by the

operator controls the force of the pull.

C. The draw works contains all of the controls to divert the rig power to needed

operations.

V-Door Ramp - The ramp which connects the “V” door to the cat walk.

Sand line -The sand line is a small draw works system. The line is generally used for

running surveys or fishing for lost surveys. These units are usually integral parts of the

draw works.

Kelly Spinner - A pneumatic operated spinner located above the kelly. It is used to spin the

kelly to make up tool joints when making connections. The kelly spinner can generally

spin clockwise to speed up connections.

Tongs - Large wrench-like devices that are used to tighten up and break out tool joints or

connections. The tongs are connected to the break out and make up catheads. Hydraulic

tongs are generally used to make up casing and tubing, deriving power from a hydraulic

unit.

Auxiliary Brakes - The draw works generally have two braking systems; the band-type

brakes on the draw works drum, and the auxiliary brakes. The auxiliary brakes are used

only when going in the hole on a trip. These are used to prevent burning the band-type

brakes. The auxiliary brakes are of two types: hydro-dynamic or electromagnetic

Deadline Reel and Clamp - The drilling line strung through the traveling block and to the

draw works is secured by the deadline, which is wrapped around the deadline reel and

clamped. This prevents the line from slipping and the traveling block from falling.

Mud Pumps - Mud pumps are used for circulating the drilling fluid down the drill pipe and

out of the annulus. These are high-pressure and high-volume pumps. They can be double-

acting duplex pumps or single-acting triplex pumps.

A: The double-acting duplex pump has four pumping actions per pump cycle.

B: The single-acting triplex pump has three pumping actions per pump cycle.

Shale Shaker - The shale shaker is a contaminant removing device. It is used to remove

the coarser drill cuttings from the mud. This is generally the first solids-removing

device and is located at the end of the flow line. The shale shaker is composed of one

or more vibrating screens though which mud returns pass.

Desander - Desilter- The desander and desilters are for contaminant or solids removal

purposes. These devices separate sand-size particles from the drilling mud. Both

devices operate like a hydrocyclone. The mud is pumped in at the top of the cyclone.

This causes the mud stream to hit the vortex finder which forces the mud down the

cyclone in a whirling fashion towards the apex of the cyclone. The heavier particles are

forced outward faster than the smaller particles. The heavier particles on the outside of

the whirling fluid are deposited out of the apex while the much smaller particles follow

the path of the liquid and reverse their path in the center and flow out of the cyclone

through the vortex finder. If used as a desander or desilter, the waste product is

deposited at the bottom and the fluid moving trough the vortex finder is returned to the

active system. If used as a clay ejector, the under-flow contains barite particles which

are returned to the mud system, while the fluid moving out of the vortex is deposited as

waste.

Degasser - This vessel is used for gas contamination removal. It consists of a vessel

which has inclined flat surfaces in thin layers and a vacuum pump. The mud is allowed

to flow over the inclined thin layers which help break out entrained gas in the mud. The

vacuum pump reduces the pressure in the vessel to about 5 psi which extracts the gas

from the mud. This device is about 99% efficient.

Mud Gas Separator - This is generally the first device available to extract gas from the

mud. It consists of a tower with baffle plates, which are flat plates that force the fluid

through a certain path. The mud is allowed to flow in the tower over the baffle plates

which separate some of the entrained gas. This device generally can extract 50% to

60% of the gas.

The accumulator is a hydraulic system that maintains and stores enough high-pressured

fluid to operate every function of the blow-out preventors (BOP’s) at least once and

still have a reasonable reserve, as defined by the governing agency rules. The system

has a pump which pumps the hydraulic fluid into storage bottles. The storage bottles

have floats which separate the hydraulic fluid from the gas (nitrogen) in the upper part

of the chamber. As fluid is pumped into the chamber bottles, the gas is compressed,

resulting in the pressure needed to move the hydraulic fluid to operate the BOP’s.

Bag-Type Preventers (Annular Preventers) this preventer is used the most because the

rubber sealing element can conform to any shape or size conduit in the hole. The

annular preventer can further collapse completely and seal the annulus with no conduit

to the hole. (This is not recommended.) The annular preventers consist of a rubber-

covered, metal-ribbed sealing element. This element is caused to collapse and seal by

allowing the pressurized hydraulic fluid from the accumulator to move a tapered, form-

fitted cylinder against the rubber which causes collapse.

Ram Preventers - This type BOP is used mainly as a backup to the bag-type preventer

or for high-pressure situations.

A. The pipe rams have two rams on opposite sides that close by moving

towards one another. The ram themselves have semicircular openings which

match the diameter of pipe being used. Each different size pipe requires

correctly sized rams.

B. If a tapered string is being used to drill a well, such as a 5” drill pipe and a

3-1/2” drill pipe, then two ram-type preventers must generally be used. This

type preventer cannot allow the pipe to be worked through it.

C. The blind rams do have the semicircular opening of the pipe rams. Instead,

the front surface of the blind rams is flat, and they can only be used to seal

the annulus when there is no pipe in the hole.

D. The shear blind rams are designed to cut through the drill pipe and seal the

hole. this type of preventer should only be used as a last resort.

Diverter System - The diverter system is used in conjunction with the annular preventer to

divert the path of mud flow either overboard or through the mud gas separation facilities.

This system is generally only used when drilling at shallow depths where the formation has

a weak fracture gradient. This system generally consists of a drilling spool with two 4”

outlets. Attached to the outlets is a valve or valves which connect to a line leading away

from the rig.

Choke Manifold- This is a system of valves and lines which are attached to the choke line,

and in some cases, kill line. The manifold is used to help control a well that has kicked by

diverting the flow to various functions such as an adjustable choke. It is designed for

versatility in diverting the mud flow after experiencing a kick.

Adjustable Choke - The adjustable choke is usually hydraulically controlled from a remote

panel located on the rig floor. The purpose of the adjustable choke is to hold the correct back

pressure on a well when controlling a kick so as not to allow any more formation fluid into

the hole and/or prevent breaking the formation down while controlling the well.

HCR Valve - the HCR valve is a hydraulically operated gate valve. This valve is used on

diverter systems and chokes lines leading from the blow out preventers. The advantage of

the valve is that it can be operated remotely.

Float - The float is a check valve run in a special sub in the bottomhole assembly. It prevents

any back-flow up the drill pipe. This should be run in shallow drilling operations to help

control “shallow” kicks.

Mouse Hole - A section of steel casing that extends below the rig floor where drill pipe is

placed to be made up in the drill string or to the kelly. It is further used in laying down drill

pipe. The joint of drill pipe is broken off in the mouse hole, picked up with the sir hoist or

catline, and moved out the V-door down to the catwalk.

Drill Collars - The drill collars are thick-walled heavy steel tubulars used to apply weight to

the bit. The drill collars should take all of the compressive loading, leaving the drill pipe in

tension.

Drill Pipe - The major part of the drill string is composed of drill pipe. Drill pipe is hot-

rolled, pierced, seamless tubing. Drill pipe is specified by its outside diameter, weight per

foot, steel grade, and range (length). The drill pipe transmits rotation, vertical movement and

drilling fluid to the bit.

Heavyweight Drill Pipe - Thick-walled heavy drill pipe is used in lieu of drill collars. It is

generally used in high-angled well where too many drill collars hamper drilling operations.

Standpipe - The standpipe is that pipe which carries mud from the rig floor into the derrick

to the kelly hose. It must be pressure-tested to the working pressure of the BOP’s.

Kelly Hose - The kelly hose is a section of high-pressured hose connecting the standpipe

and the swivel. The kelly hose allows for the vertical movement of the drill string as well as

circulation of fluid down the drill string.

Substructure - the substructure provides the support for the derrick and derrick loading. It

also provides the necessary clearance beneath the rig floor for the preventor stack.

Cat Walk - The cat walk is where the pipe is laid down from the drill floor. Any elevated

walkway may be referred to as a catwalk.

COMPONENTS OF JACK UP RIGS AND THEIR FUNCTION

There are some main components of a Jack up Unit:

01. Derrick

Load-bearing tower like framework over an oil/gas well which holds the hoisting

and lowering equipment.

02. Draw works

Hoisting mechanism on a drilling rig which spools off or takes in the drilling line

and thus raises or lowers the drill string and bit.

03. Drill Floor

Foundation on which the derrick and engines sit. Contains space for storage and

well control equipment.

04. Drill pipe

Steel pipe, in approximately 30-foot (9-meter) lengths, screwed together to

form a continuous pipe extending from the drilling rig to the drilling bit at the

bottom of the hole. Rotation of the drill pipe and bit causes the bit to bore

through the rock.

05. Drill String

String of individual joints of pipe that extends from the bit to the Kelly

and carries the mud down to, and rotates, the bit. 06. Cantilever

The platform carrying the drill floor and derrick.

Skids in and out of rig.

07. Legs

The 3 or 4 legs of a jack-up rig are lattice

structures made from vertical, horizontal and

diagonal tubes. They can move up and down using

jacking motors/gears.

08. Living Quarters

Where the crew lives. Up to 120 men onboard.

09. Helipad

For reception of helicopters delivering supplies andchange of crew.

10. Hull

Main structure of the rig. Triangular rigid and water-tight.

11. Spud Can

Circular ‘shoes’ of the legs. Designed to penetrate deep into the seabed for good foothold.

These are most important and necessary components of a jack up rig. On the continuation of the

article we will discuss about this items and the other equipment that are exist on a jack up and their

function, types and etc.

On the next page the above mentioned components are showed. All above described items will be

explain in technical word and more complete.

A jack up rig and components.14

Derrick

The term derrick comes from Thomas Derrick, a hangman who invented a type of gallows using a

movable beam and pulley system during the Elizabethan era. During his lifetime, Derrick executed

over 3,000 people, many of them with his modified gallows device, and the supporting framework

for his gallows came to be known as a derrick. The term was adopted to describe cranes and other

lifting devices which used a similar support mechanism.

An oil derrick is a drilling rig designed for use in oil and natural gas production. The basic oil

derrick has an upright stationary section which is potentially capable of supporting hundreds of tons

of weight, combined with a movable boom which is used to raise and lower equipment. Derricks of

various designs have been in use for centuries to extract valuable resources from under the Earth,

and continue to be widely used today. Early derricks consisted of a framework which was designed

to hold a large pole used for percussive drilling, which is accomplished by repeatedly beating the

earth to make a hole. A modern oil derrick typically uses a drill bit which is capable of biting

through the substrate, and cooled with constant slurry of mud to prevent it from getting too hot.

Typically, as the drill bit sinks in, the hole is lined to prevent a cave in. Once the drill reaches the

oil, it is withdrawn so that pumps and pipes can be inserted into the hole to extract it. The basic oil

derrick design is familiar to residents of areas rich in oil, and is also used on offshore oil drilling

platforms which extract water from under the ocean. A large oil derrick requires an extensive crew

to run properly, and is often located in a field of similar derricks, all of which operate on a constant

basis. The oil derrick crew typically includes geologists, engineers, mechanics, and safety

inspectors to ensure that the workplace is well maintained.

Some picture of derrick.15

Picture of a derrick in operation.16

Types of Derricks:

Triple- has the capacity of pulling 90’ stands of pipe

Double- has the capacity of pulling 60’ stands of pipe

Single- has the capacity of pulling 30’stands of pipe (one 30-ft joint)

Standard Derricks - Four sided structures that must be assembled and disassembled when

transporting.

Portable Derricks - Telescoping and jackknife types.

The telescoping derrick is raised and lowered in an extending and collapsing fashion and

lowered in one piece, but may be disassembled to some degree after being lowered.

Draw works (Heart of the rig) The primary function of the draw works is to reel out and reel in the drilling line, a large diameter

wire rope, in a controlled fashion. The drilling line is reeled over the crown block and traveling

block to gain mechanical advantage in a "block and tackle" or "pulley" fashion. This reeling out and

in of the drilling line causes the traveling block, and whatever may be hanging underneath it, to be

lowered into or raised out of the well bore. The reeling out of the drilling line is powered by

gravity and reeling in by an electric motor or diesel engine.

The principal parts of the draw works are the drum, the drum brakes, transmission, and cathead.

The principal function is to convert the power source into a hoisting operation and provide braking

capacity to stop and sustain the weights imposed when lowering or raising the drill string.

Draw work.17

Diagram of draw works and component.18

As can be observed in above pictures there are some components related to the draw works. In the

continuation of this article we will explain most important part of draw works briefly.

Crown Block - A series of sheaves affixed in the top of the derrick used to

change the direction of pull from the draw works to the traveling block. On

the other word a Crown block is the stationary section of a block and

tackle that contains a set of pulleys or sheaves through which the drill

line (wire rope) is threaded or reeved and is opposite and above the traveling

block.

Crown block.19

As can be understand, crown block has to endure loads and carry out its function. There is a simple

equation to evaluate load on crown block. This formula can be writing as:

1: Static crown load for two sheaves (SCL) = fast-line load+ hook load+ deadline load

SCL= W /2+ W+W/2=2W

2: Static crown load for three sheaves

SCL= W/4+ W+W/4=3/2W

1: Static crown load for N lines or sheaves

SCL=W/N+W+W/N= (1+2/N)W

Traveling Block A Traveling block is the free moving section of a block and tackle that contains a set

of pulleys or sheaves through which the drill line (wire rope) is threaded

or reeved and is opposite (and under) the crown block (the stationary section).

On the other word traveling block is a movable unit, consisting of sheaves, frame,

clevis, and hook, connected to, and hoisted or lowered with, the load in a block-and-

tackle system. Also known as floating block; running block.

Traveling block.20

Drilling hook The drilling hook, capable of swiveling, is attached to the underside of traveling

block. This hook serves to join the hoisting equipment to 1) the swivel which

suspends the drill string, or 2) the elevator which grips a stand or column of casing,

tubing, or drill pipe to be raised or lowered in to the hole.

Drilling hook.21

Top drive It is a device that turns the drill string. It consists of one or more motors (electric or

hydraulic) connected with appropriate gearing to a short section of pipe called a

quill, that in turn may be screwed into a saver sub or the drill string itself. The top

drive is suspended from the hook, so the rotary mechanism is free to travel up and

down the derrick. This is radically different from the more conventional rotary table

and kelly method of turning the drill string because it enables drilling to be done

with three joint stands instead of single joints of pipe. It also enables the driller to

quickly engage the pumps or the rotary while tripping pipe, which cannot be done

easily with the kelly system. While not a panacea, modern topdrives are a major

improvement to drilling rig technology and are a large contributor to the ability to

drill more difficult extended-reach wellbores. In addition, the top drive enables

drillers to minimize both frequency and cost per incident of stuck pipe.

Top drive.22

Drill floor

The Drill Floor is the heart of any drilling rig and is also known as the pad. This is the area where

the drill string begins its trip into the earth. It is traditionally where joints of pipe are assembled, as

well as the BHA (bottom hole assembly), drilling bit, and various other tools. This is the primary

work location for roughnecks and the driller. The drill floor is located directly under the derrick.

Drilling floor.23

Drilling floor.24

Drill floor device has two or more mouse holes for assembly and disassembly of pipe string

sections. The mouse holes are arranged to be displaced underneath the drill floor by a drive system

and positioned under a hole or an opening in the drill floor. At least one of the mouse holes is

provided with an elevator arranged to raise and lower a pipe or a pipe string section located in the

mouse hole, between an upper working position in which the upper end of the pipe/pipe string

section projects above the drill floor and a lower position of rest in which the upper end of the

pipe/pipe string section is below the drill floor. increasing the depth of the mouse hole allows a

pipe or a stand located in the mouse hole to be lowered to a lower position of rest where the upper

end of the pipe/stand is below the drill floor. An empty mouse hole, or a mouse hole where a pipe

or a stand has been lowered as indicated, may be moved horizontally underneath the drill floor, as

mentioned above. Positioning a mouse hole containing a lowered pipe or a lowered stand under an

opening in the drill floor and then making the mouse hole shallower by raising the pipe support,

allows the upper end of the pipe/stand to be brought to a working height above the drill floor. By

use of the invention a three-pipe stand can be constructed in the following way. An empty first

mouse hole is positioned under an opening in the drill floor, and a first single pipe is brought to a

vertical position through the opening and placed in the mouse hole, by use of previously known

equipment. The pipe support of the mouse hole is placed at a distance below the drill floor that

leaves the upper end of the pipe at a working height above the drill floor, making it easy to

disengage the lifting equipment. The depth of the mouse hole is increased by lowering the pipe

support until the upper end of the pipe is below the drill floor, and the mouse hole is displaced

horizontally away from the opening in the drill floor. An empty second mouse hole is brought into

position under the opening in the drill floor, and a second pipe is placed in this second mouse hole.

A third pipe is brought into the area over the second mouse hole and is coupled to the upper end of

the second pipe, which projects above the drill floor. This creates a two-pipe stand which is then

lifted out of the second mouse hole. The now empty second mouse hole is displaced horizontally

underneath the drill floor away from the opening in the drill floor, and then the first mouse hole

containing the first pipe is positioned under the opening. The first pipe is raised by means of the

elevator and the pipe support, lifting the upper end of the pipe through the opening and up to

working height. The two-pipe stand consisting of the second and third pipes is lowered and added

to the upper end of the first pipe, whereby a three-pipe stand is created, which is lifted out of the

mouse hole in the assembled state and placed in intermediate storage or brought to the central area

of the drill floor for use in a pipe string. As is evident from the above, it is sufficient for the first

mouse hole to be provided with raisable/lowerable pipe support.

Drill pipe and drill string

Drill pipe is hollow, thick-walled, steel tubing that is used on drilling rigs to facilitate the

drilling of a wellbore and comes is a variety of sizes, strengths and weights but are typically 30

to 33 feet in length. They are hollow to allow drilling fluid to be pumped through them, down

the hole and back up the annulus. Because it is designed to support it's own weight for

combined lengths that often exceed 1 mile down into the crust of the Earth, the case hardened

steel tubes are expensive, and owner's spend considerable efforts to re-use them after finishing a

well, replacing the drill stems with thinner walled tubular casing, tapping the natural resources

of oil reservoirs. Used drill stem is often sent to a yard for inspection, sorted, and stored until

new drill sites can be explored.

Drilling pipe.25

Also, a drill string on an oil rig is a column, or string, of drill pipe that transmits drilling fluid (via

the mud pumps) and rotational power (via the kelly drive or top drive) to the drill bit. The term is

loosely applied as the assembled collection of the drill pipe, drill collars, tools and drill bit. The

drill string is hollow so that Drilling fluid can be pumped down through it and circulated back up

the annulus (void between the drill string and the formation). The drill string is an assembly of

components, from the bit to the swivel, used for drilling by rotary method.

In the below picture the drilling string and its components arrangement has been shown.

Drill string and arrengment.26

Kelly is a square or hexagonal member at the upper most part of the drill string (immediately

below the swivel) that passes through a properly fitting bushing known as the Kelly bushing or

drive bushing. The drive bushing transmits rotary motion to the kelly which results in the turning

of the drill string.

A Swivel is a mechanical device used on a drilling rig that hangs directly under the traveling

block and directly above the kelly, that provides the ability for the kelly (and subsequently the drill

string) to rotate while allowing the traveling block to remain in a stationary rotational position (yet

allow vertical movement up and down the derrick) while simultaneously allowing the introduction

of drilling fluid into the drill string.

Swivel.27

Drill bit are at the end of the drill string that actually cuts up the rock; comes in many shapes and

materials (tungsten carbide steel, diamond) that are specialized for various drilling tasks and rock

formations.

Type of drilling bit.28

Cantilever

Cantilever is a projecting beam or other horizontal member supported at one or more points but not

at both ends. Some engineers distinguish between a cantilever, supported at only one fixed end, and

an overhanging beam that projects beyond one of its end supports. The free, unsupported end is

capable of supporting a weight or surface, such as a concrete slab. Any beam built into a wall with a

projecting free end forms a cantilever, which may carry a balcony, canopy, roof, or part of a

building above. Cantilevering can be used for constructions as simple as bookshelves or as

complicated as bridges. Most of our jack-up rigs are equipped with a cantilever system that enables

the rig to cantilever or extend its drilling package over the aft end of the rig. This is particularly

important when attempting to drill over existing platforms. Cantilever rigs have historically enjoyed

higher day rates and greater utilization compared to slot rigs.

Cantilever.29

Method and apparatus for transferring a derrick from a jack-up rig to an offshore platform are

disclosed which include positioning the rig and platform next to each other, providing an elevator

pad on the platform that is set at the same level as the deck of the rig, installing skid beams between

the deck of the rig and the top of the elevator pad, skidding the rig from the rig to the pad, and

lowering the pad and derrick to the normal level of the platform for use in drilling operations. On

the other word; in aligning the skid beams of the jack-up rig with those on the top of the upper

platform section, the jack-up rig is jacked up and anchored at a level where the longitudinal beams

are just above the rails on the top of the upper platform section. The upper platform section is then

slowly raised until the rails carried at the top thereof are in horizontal alignment with the

longitudinal beams of the jack-up platform so that the derrick thereof can be skidded laterally onto

the upper platform section. Subsequently, the upper platform section together with the derrick now

mounted thereabove, is lowered by the jacks until the jacks are totally retracted and the upper

platform section rests at the tope of the platform on the skid beams below the upper platform

section. In this manner, the jacks do not have to support the heavy hook loads which are

encountered during normal drilling operations.

Cantilever.30

How to skid Cantilever.31

Rack and Pinion Skidding Systems are used for moving the cantilever and the drill floor of a jack-up rig in order to locate the well center at correct position

Leg and spud can

The legs and footings of a Jack Up are steel structures that support the hull when the Unit is in the

Elevated mode and provide stability to resist lateral loads. Footings are needed to increase the soil

bearing area thereby reducing required soil strength. The legs and footings have certain

characteristics which affect how the Unit reacts in the Elevated and Afloat Modes, while going on

location and in non-design events. The legs of a Jack Up Unit may extend over 500 ft above the

surface of the water when the Unit is being towed with the legs fully retracted. Depending on size

and length, the legs usually have the most detrimental impact on the afloat stability of the Unit. The

heavy weight at a high center of gravity and the large wind area of the legs combine to dramatically

affect the Unit’s afloat stability. For Units of the same hull configuration and draft, the Unit with

the larger legs will have less When in the Elevated Mode; the legs of a Jack up Unit are subjected to

wind, wave, and current loadings. In addition to the specifics of the environment, the magnitude and

proportion of these loads is a function of the water depth, air gap (distance from the water line to the

hull baseline) and the distance the footings penetrate into the seabed. Generally, the larger the legs

and footings, the more load wind, wave, and current will exert on them. Legs of different design

and size exhibit different levels of lateral stiffness (amount of load needed to produce a unit

deflection). Jack Up stiffness decreases with increases in water depth (or more precisely, with the

distance from the support footing to the hull/leg connection). Furthermore, for deeper water depths,

flexural stiffness (chord area and spacing) overshadows the effects of shear stiffness (brace). Leg

stiffness is directly related to Jack Up stiffness in the elevated mode, thereby affecting the amount

of hull sway and the natural period of the Unit (which may result in a magnification of the

oscillatory wave loads). All Jack Up Units have legs. Their purpose is to provide elevation of the

hull above the storm wave crest; withstand wave, current, and wind loads; and to transmit

operational, environmental, and gravity loads between the hull and footings. There are two kind of

legs; cylindrical and trussed. Cylindrical legs are hollow steel tubes. They may or may not have

internal stiffening, and may have rack teeth or holes in the shell to permit jacking of the hull up and

down the legs. Cylindrical legs are currently found on Units operating in water depths less than 300

feet. The newer Units operating in water depths of 300 feet and greater all have trussed legs. The

main reason for this is that cylindrical legs require more steel to provide the same resistance to

environmental loads and provide the same elevated response as truss legged Units The primary

advantage of cylindrical legs is for Units that operate in shallow water as these Units are normally

smaller and have less deck area. Cylindrical legs take up less deck area and are generally less

complicated requiring less experience to construct than trussed legs.

Trussed legs consist of chords and braces. In general, the braces provide the shear capacity of the

leg while the chords provide the axial and flexural stiffness. One of the main benefits of the Trussed

legs is that they allow for optimal steel utilization and result in lighter stiffer legs with reduced drag

loads.

Trussed 4legs jack up.32

Cylindrical 3legs jack up.33

3-Lgged versus 4-legged jack ups The great majority of Jack up Units in the world have no more than four legs,

with three being the minimum required for stability. There are some Units built with

more than four legs. Units with 3 legs have the legs arranged in some triangular

form. The main advantage of three-legged Units is that they completely eliminate the

need to build extra leg(s). Furthermore, for a given hull size, they can carry more

deck load in the afloat mode; and usually have a reduced number of elevating units

(pinions, cylinders, etc), resulting in reduced power/maintenance requirements, and

less weight. Disadvantages of three-legged units include the fact that they require

preload tankage and they have no leg redundancy. Units with 4-legs usually have the

legs arranged in some rectangular form. Four legged Units require little or no preload

tanks on board. This is because four-legged Units can preload two legs at a time

using the elevated weight as preload weight. This results in a savings of piping and

equipment weights, and more usable space within the hull. Because of the fourth leg,

these Units are stiffer in the elevated mode than a three-legged Unit. This apparent

advantage may be offset by the fact that the additional leg adds wind, wave and

current loads. In the afloat transit mode, the fourth leg is a disadvantage as its weight

causes a direct reduction in the afloat deck load when compared to an equivalent

three-legged unit.

3-chorded legs versus 4-corded legs Trussed legs have either 3 or 4 main vertical structural members called

chords. All trussed-leg Jack Up Units operating today have one of these chord

arrangements. In essence, the benefits and disadvantages of three- versus four-

chorded legs are comparable in nature to those of three- and four-legged Jack Ups

(i.e., overall weight/drag loads and redundancy), except that they do not affect

preloading procedures in any way.

How to elevate In the offshore oil and gas well drilling and production industry, it is common to use

jack-up barges or jack-up rigs for many purposes. These rigs can be used to repair or

work over oil and gas wells. Very large jack-up rigs are fitted as oil and gas well

drilling rigs for drilling for oil and gas in a marine environment.

It is known in the art to use an elevating system for raising a barge relative to the

legs of a jack-up rig using a rack and pinion type gearing mechanism. In such a case,

a plurality of pinion gears engages a toothed rack mounted on each leg of the jack-up

rig. It is also known to mount such a rack on a truss-type leg that is typically

triangular or square in horizontal cross section or cylindrical pipe.

When using such a rack and pinion type elevating mechanism, there is a need for a

brake system for locking the elevating unit relative to the leg when the hull is to be

fixed at a desired position relative to the underlying waters surface.

“Elevating Equipment” refers to the equipment and systems aboard a Jack up Unit

which are necessary for the Jack Up to raise, lower, and lock-off the legs and hull of

the Jack Up. All Jack ups have mechanisms for lifting and lowering the hull. The

most basic type of elevating system is the pin and hole system, which allows for hull

positioning only at discrete leg positions. However, the majority of Jack Ups in use

today are equipped with a Rack and Pinion system for continuous jacking operations.

There are two basic jacking systems: Floating and Fixed. The Floating system uses

relatively soft pads to try to equalize chord loads, whereas the Fixed system allows

for unequal chord loading while holding. There are two types of power sources for

Fixed Jacking Systems, electric and hydraulic. Both systems have the ability to

equalize chord loads within each leg. A hydraulic-powered jacking system achieves

this by maintaining the same pressure to each elevating unit within a leg. Care must

be taken, however, to ensure that losses due to piping lengths, bends, etc., are either

equalized for all pinions or such differences are insignificant in magnitude. For an

electric powered jacking system, the speed/load characteristics of the electric

induction motors cause jacking motor speed changes resulting from pinion loads,

such that if jacking for a sufficiently long time, the loads on any one leg tend to

equalize for all chords of that leg. All Jack Ups have mechanisms to guide the legs

through the hull. For Units with Pinions, the guides protect the pinions from

“bottoming out” on the rack teeth. As such, all Units are fitted with a set of upper

and lower guides. Some Jack up Units, which have exceptionally deep hulls or tall

towers of pinions, also have intermediate guides. These guides function only to

maintain the rack the correct distance away from the pinions and are not involved in

transferring leg bending moment to the hull. Guides usually push against the tip

(vertical flat side) of the teeth, but this is not the only form of guides. There are also

other forms of guides such as chord guides, etc. Depending on accessibility, some

guides are designed to be replaced and are sometimes known as “wear plates.” In

addition to protecting the pinions and hull, all upper and lower guides are capable of

transferring leg bending moment to the hull to some degree determined by the

design. The amount of moment transferred by the guides to the hull as a horizontal

couple is dependant on the relative stiffness of the guides with respect to the stiffness

of the pinions and/or fixation system (if any).

Rack and pinion system.34

Leg and its elevating equipment.35

Spud can Most of the jack-up rig has three legs, each equipped with a shallow conical

underside footing known as a ‘spud-can'. Spud cans are footings of a jack-up unit that is commonly

employed for offshore drilling when the water depth is less than 100m. The footing is an inverted

conical structure with polygonal plane area and its diameter typically ranges from 10 to 25m. As the

spud can size increases, the bearing pressure decreases, resulting in lower soil penetration will be

happened. Larger spud can size, however may require larger leg well openings on the hull, reducing

its afloat stability and its capacity to pick up buoyancy forces in the event of rapid penetration.

Spud can and penetration.36

Helipad A helicopter deck (or heli deck) is a helicopter pad on the deck of a jack up, usually located on

the stern and always clear of obstacles that would prove hazardous to a helicopter landing. In

the U.S. Navy it is commonly and properly referred to as the flight deck. In the Royal

Navy, landing on is usually achieved by lining up slightly astern and on the port quarter, as the

ship steams into the wind and the aircraft captain slides across and over the deck. Shipboard

landing for some helicopters is assisted though use of a haul-down device that involves

attachment of a cable to a probe on the bottom of the aircraft prior to landing. Tension is

maintained on the cable as the helicopter descends, assisting the pilot with accurate positioning

of the aircraft on the deck; once on deck locking beams close on the probe, locking the aircraft

to the flight deck. This device was pioneered by the Royal Canadian Navy and was called

"Beartrap". The U.S. Navy implementation of this device, based on Bear trap, is called the

"RAST" system (for Recovery Assist, Secure and Traverse) and is an integral part of

the LAMPS MK III (SH-60B) weapons system. A secondary purpose of the haul-down device

is to equalize electrostatic potential between the helicopter and ship. The whirling rotor blades

of a helicopter can cause large charges to build up on the airframe, large enough to cause injury

to shipboard personnel should they touch any part of the helicopter as it approaches the deck.

This was depicted in the 1990 motion picture The Hunt for Red October. In the film,

CIA analyst Jack Ryan (Alec Baldwin) is flown out to the submarine Dallas in a helicopter.

With no place to land, Ryan has to be lowered to the Dallas, but brushes the officer charged

with trying to hook him. The officer is shocked and receives a minor injury. Ryan releases

himself from the harness and is rescued by divers. Coaxial rotor helicopters in flight are highly

resistant to side-winds, which makes them suitable for shipboard use, even without a rope-

pulley landing system.Marine and Offshore Helicopter decks onboard offshore oil platforms and

Ships are typically regulated by the rules defined within CAP 437, which defines standards for

the design and marking, and lighting of Marine/offshore Helicopter decks, and is produced by

the Civil Aviation Authority. The Largest Marine Heli decks will accommodate the Boeing CH-

47 Chinook , which requires a D value of 30m, and has a weight of 21.3t.

Helipad of jack up.38

Hull The Hull of a Jack up Unit is a watertight structure that supports or houses the equipment,

systems, and personnel, thus enabling the Jack Up Unit to perform its tasks.

When the Jack up Unit is afloat, the hull provides buoyancy and supports the weight of the legs

and footings (spud cans), equipment, and variable load. Different parameters of the hull affect

different modes of operation of the Unit. These are described below.

In general, the larger the length and breadth of the hull, the more variable deck load and

equipment the Unit will be able to carry, especially in the Afloat mode (due to increased deck

space and increased buoyancy). Also, larger hulls generally result in roomier machinery spaces

and more clear space on the main deck to store pipe, 3rd Party Equipment, and provide for clear

work areas. The larger hull may have larger preload capacity that may permit increased

flexibility in preloading operations.

Larger hulls generally have the negative effects of attracting higher wind, wave and current

loads. Since Jack Ups with larger hulls weigh more, they will require more elevating jacks of

larger capacity to elevate and hold the Unit. The large weight also affects the natural period of

the Jack up Unit in the elevated mode. The draft of the hull, or the distance from the afloat

waterline to the baseline of the hull, has a direct effect on the amount of variable deck load that

can be carried and the stability when afloat. The draft of the hull has an opposing relationship

with the hull’s freeboard, or the distance from the afloat waterline to the main deck of the hull.

Every incremental increase in the draft of a Jack Up decreases the freeboard by the same

increment. For units with identical hulls, the one with the deeper draft weighs more. This

increased weight could be in the form of lightship weight or variable deck load. Conversely, for

Units with identical hulls, the unit with the deeper draft will have less afloat stability than the

unit with shallower draft. Perhaps the most influential parameter in a Jack Up unit’s afloat

stability is freeboard. For units with identical hulls and leg length, the one with the larger

freeboard will have the larger afloat stability margin.

The equipment required to satisfy the mission of the Jack up Unit affects both the hull size and

lightship weight of the Unit. There are three main groups of equipment on a Jack up Unit, the

Marine Equipment, Mission Equipment, and Elevating Equipment.

“Marine Equipment” refers to the equipment and systems aboard a Jack up Unit that are not

related to the Mission Equipment. Marine Equipment could be found on any sea-going vessel,

regardless of its form or function. Marine Equipment may include items such as main diesel

engines, fuel oil piping, electrical power distribution switchboards, lifeboats, radar,

communication equipment, galley equipment, etc. Marine Equipment, while not directly

involved with the Mission of the Jack up Unit, is necessary for the support of the personnel and

equipment necessary to carry out the Mission. All Marine Equipment is classified as part of the

Jack up Lightship Weight. “Mission Equipment” refers to the equipment and systems aboard a

Jack up Unit, which are necessary for the Jack Up to complete its Mission. Mission Equipment

varies by the mission and by the Jack Up. Two Jack up Units which are involved in Exploration

Drilling may not have the same Mission Equipment. Examples of Mission Equipment may

include derricks, mud pumps, mud piping, drilling control systems, production equipment,

cranes, combustible gas detection and alarms systems, etc. Mission Equipment is not always

classified as part of the Jack up Lightship Weight. Some items, such as cement units, are

typically classified as variable deck load as they may not always be located aboard the Jack Up.

“Elevating Equipment” refers to the equipment and systems aboard a Jack up unit which are

necessary for the Jack Up to raise, lower, and lock-off the legs and hull of the Jack up.

All Jack up Units must load the soil that supports them to the full load expected to be exerted on

the soil during the most severe condition, usually Storm Survival Mode. This preloading

reduces the likelihood of a foundation shift or failure during a Storm. The possibility does exist

that a soil failure or leg shift may occur during Preload Operations. To alleviate the potentially

catastrophic results of such an occurrence, the hull is kept as close to the waterline as possible,

without incurring wave impact. Should a soil failure or leg shift occur, the leg that experiences

the failure loses load-carrying capability and rapidly moves downward, bringing the hull into

the water. Some of the load previously carried by the leg experiencing the failure is transferred

to the other legs potentially overloading them. The leg experiencing the failure will continue to

penetrate until either the soil is able to support the leg, or the hull enters the water to a point

where the hull buoyancy will provide enough support to stop the penetration. As the hull

becomes out-of-level, the legs will experience increased transverse load and bending moment

transferred to the hull mostly by the guide. With the increased guide loads, some braces will

experience large compressive loads. There are detailed procedures to be followed during such a

failure to minimize the structural damage, but these are beyond the scope of this primer. During

normal preload operations it is important to keep the weight of the hull, deck load, and preload

as close to the geometric center of the legs as possible, as this will assure equal loading on all

legs. Sometimes, however, single-leg preloading is desired to increase the maximum footing

reaction of any one leg. This is achieved by selective filling/emptying of preload tanks based on

their relative position to the leg being preloaded. Preload is water taken from the sea and

pumped into tanks within the hull. After the preload is pumped on board, it is held for a period

of time. The Preload Operation is not completed until no settling of the legs into the soil occurs

during the holding period while achieving the target footing reaction. The amount of preload

required depends on the required environmental reaction and the type of Jack Up Unit. Mat

Units normally require little preload. Four-legged independent Units usually require little or no

preload water. This is because four-legged Units preload two diagonally opposite legs at a time

using the weight of the hull. These Units jack to their preload air gap, then lift two legs slightly

off the seabed. This causes the Unit to settle on the other two legs. The hull is jacked back up to

preload air gap, and the procedure is completed when all four legs have been preloaded to the

target footing reaction and no additional penetration takes place. Three-legged independent

Units require the most preload water. For Units that cannot jack with preload, preload water is

pumped on board after the hull reaches the preload air gap. If significant settling occurs, the

preload must be dumped before the hull is jacked to its preload air gap again, and the procedure

repeated until no settling occurs. For Units that can jack with full preload, preload is pumped

into the hull while the hull is still in the water. The hull is then jacked up, usually stopping for a

short time at certain pre-arranged drafts. This continues until the hull is at the preload air gap

and holds the preload for the holding period. Once the preload is held for the specified time, the

preload water is dumped and the Jack Up is ready to be elevated to the operating air gap.

On the continuation of this section, three groups of equipment which were mentioned will be

more detailed.

Mission Equipment

“Mission Equipment” refers to the equipment and systems aboard a Jack up Unit,

which are necessary for the Jack up to complete its Mission. Mission Equipment varies by the

mission and by the Jack up. Two Jack up Units which are involved in Exploration Drilling may

not have the same Mission Equipment. Examples of Mission Equipment may include derricks,

mud pumps, mud piping, drilling control systems, production equipment, cranes, combustible

gas detection and alarms systems, etc. some of mission equipments as an example , derrick, has

been detailed in previous pages.

Mud pump In geotechnical engineering, drilling fluid is a fluid used to

drill boreholes into the earth. Often used while drilling oil and natural gas wells and

on exploration drilling rigs, drilling fluids are also used for much simpler boreholes,

such as water wells. The three main categories of drilling fluids are Water based mud

(which can be dispersed and non dispersed), non aqueous mud, usually called oil

based mud, and gaseous drilling fluid, in which a wide range of gases can be used.

The main functions of drilling fluids include providing hydrostatic pressure to

prevent formation fluids from entering into the well bore, keeping the drill bit cool

and clean during drilling, carrying out drill cuttings and suspending the drill cuttings

while drilling is paused and the drilling assembly is brought in and out of the hole.

The drilling fluid used for a particular job is selected to avoid formation damage and

to limit corrosion. Many types of drilling fluids are used on a day to day basis. Some

wells require that different types be used at different parts in the hole, or that some

types be used in combination with others. The various types of fluid generally fall

into a few broad categories:

Air - compressed air is pumped either down the bore holes annular space or down

the drill string itself.

Air/water - Same as above, with water added to increase viscosity, flush the hole,

provide more cooling, and/or to control dust.

Air/polymer - A specially formulated chemical, most often referred to as a type of

polymer, is added to the water & air mixture to create specific conditions. A foaming

agent is a good example of a polymer.

Water - Water by itself is pumped to do very specific things in very specific

formations.

Water-Based Mud (WBM) - A most basic water-based mud system begins with

water, then clays and other chemicals are incorporated into the water to create a

homogenous blend resembling something between chocolate milk and a malt

(depending on viscosity). The clay (called "shale" in its rock form) is usually a

combination of native clays that are dissolved into the fluid while drilling, or specific

types of clay that are processed and sold as additives for the WBM system. The most

common of these is betonies, frequently referred to in the oilfield as "gel". Gel likely

makes reference to the fact that while the fluid is being pumped, it can be very thin

and free-flowing (like chocolate milk), though when pumping is stopped, the static

fluid builds a "gel" structure that resists flow. When an adequate pumping force is

applied to "break the gel", flow resumes and the fluid returns to its previously free-

flowing state. Many other chemicals (e.g. Potassium Formate) are added to a WBM

system to achieve various effects, including: viscosity control, shale stability,

enhance drilling rate of penetration, cooling and lubricating of equipment.

Mud engineer, the name given to an oil field service company individual who is

charged with maintaining a drilling fluid or completion fluid system on an oil and/or

gas drilling rig. This individual typically works for the company selling the

chemicals for the job and is specifically trained with those products, though

independent mud engineers are still common. The work schedule of the mud

engineer or more properly drilling Fluids Engineer is arduous, often involving long

shifts.

In offshore drilling, with new technology and high total day costs, wells are being

drilled extremely fast. Having two mud engineers makes economic sense to prevent

down time due to drilling fluid difficulties. Two mud engineers also reduce

insurance costs to oil companies for environmental damage that oil companies are

responsible for during drilling and production. The cost of the drilling fluid is

typically about 10% (may vary greatly) of the total cost of well construction, and

demands competent mud engineers. Large cost savings result when the mud engineer

performs adequately. As every body can understand, the main device to complete

mud circuit is pump, Mud pump is a reciprocating plunger device designed to

circulate drilling fluid down the drill string and back up the annulus.

Mud pumps come in a variety of sizes and configurations but for the typical

petroleum drilling rig, the triplex (three plunger) mud pump is the pump of choice.

Bop The first line of defense in well control is to have sufficient drilling fluid

pressure in the well hole. During drilling, underground fluids such as gas, water, or

oil under pressure (the formation pressure) opposes the drilling fluid pressure (mud

pressure). If the formation pressure is greater than the mud pressure, there is the

possibility of a blowout. The blowout preventer (BOP), accumulator andchoke

manifold are installed by the rig crew after thesurface casing is set and cemented.

The accumulator and choke manifold have been set into place during rigging up and

now need to be hooked up and tested. The choke line valve is used to redirect the

mud from the well bore to the choke manifold during a kick. The kill line valve is

used to direct drilling fluid to the BOP during a kick.

The BOPs, accumulators, and choke manifold should be tested and properly

maintained.

Potential Hazards:

Being hit by hoses or sprayed by hydraulic fluid if there is a seal or hydraulic

line failure during pressure testing.

Possible Solutions:

Ensure workers stand clear of pressurized lines during testing procedures.

Mud pump.39

Drill-mud circulation system.40

A type of Bop.41

Shale shaker Shale shakers are devices that remove drill cuttings from

the drilling fluid while circulating and drilling. There are many different designs and

research into the best design is constantly ongoing since solids control is vital in

keeping down costs associated with the drilling fluid. The name shale shaker is a

description of what it does. The basic design consists of large, flat sheets of wire

mesh screens or sieves of various mesh sizes that shakes or vibrates the drill cuttings,

commonly shale, across and off of the screens as the drilling fluid flows through

them and back into the drilling fluid system, often called a mud system. This

separates the drill cuttings, often called solids, from the drilling fluid so that it can be

recirculated back down the wellbore. Drilling mud, typically a mixture of clay, water

and various additives, is pumped through a hollow drill string (pipe, drill collar, bit,

etc.) down into a well and exits through holes in a drill bit. The mud picks up

cuttings (rock bits) and other solids from the well and carries them upwardly away

from the bit and out of the well in a space between the well walls and the drill string.

At the top of the well, the solids-laden mud is introduced to a shale shaker, a device

which typically has a series of screens arranged in tiered or flat disposition with

respect to each other. The screens catch and remove solids from the mud as the mud

passes through them. If drilled solids are not removed from the mud used during the

drilling operation, recirculation of the drilled solids can create viscosity and gel

problems in the mud, as well as increasing wear in mud pumps and other mechanical

equipment used for drilling. In some shale shakers, a fine screen cloth is used with

the vibrating screen. The screen may have two or more overlying layers of screen

cloth. The frame of the vibrating screen is suspended or mounted upon a support and

is caused to vibrate by a vibrating mechanism, e.g. an unbalanced weight on a

rotating shaft connected to the frame. Each screen may be vibrated by vibratory

equipment to create a flow of trapped solids toward an end of the screen on a top

surface of the screen for removal and disposal of solids. The fineness or coarseness

of the mesh of a screen may vary depending upon mud flow rate and the size of the

solids to be removed. n certain prior art shale shakers having one (or more)

processing screens, such screens cannot adequately deal with a surge in fluid flow or

high fluid flow rates, e.g. During a “bottoms up” or riser pipe circulation condition.

La other prior art systems, the discharge of one or more shale shakers is fed to

another shale shaker for further de-liquefying and de-oiling. Such a process

necessarily requires at least two shale shakers. However, on offshore drilling rigs,

space is at a premium. For this reason, tiered or tandem shale shakers are used to

affect a finer screening of the mud on the second level. But, in high volume

operations, such tandem shale shakers may not be able to handle the throughput due

to their limited size. Accordingly, there is a need to enhance the capacity of a tandem

shale shaker during high mud volume operations without increasing their “foot

print”, i.e., the area of floor space required by the base of the tandem shale shaker.

Shale shaker system.42

Mud tank A Mud tank is an open-top container, typically made of steel, used as a reserve

store for the active circulation of the drilling fluid on a drilling rig. They are often

called mud pits, which comes from the fact that they used to be nothing more than

pits dug out of the earth. The tanks are open-top and will have walkways on top of

them to allow traversing and visual observation of the drilling fluid and to monitor

the level of fluid in the tanks. The walkways also allow access to other equipment

mounted on top of the mud tanks. For typical petroleum drilling rig there are

normally 2 tanks. Each tank is sectioned off into smaller separate compartments

designed for more specific purposes, such as a settling tank (sometimes called a sand

trap), used to allow solids such as sand to settle out of the drilling fluid before it

flows into the next compartment. Other compartments will have agitators (which are

large fan blades) that stir the fluid to prevent the chemical constituents of the drilling

fluid from settling out. All mud is drawn out of the front tank and all mud is

deposited into the rear tank, which creates a flow from the rear tank to the front tank.

There are only two paths for mud to get to the front tank, both through the sand trap

and through the overflow in the common wall forming a center divider. Mud will

take the path of least resistance, most often this is the sand trap at the bottom of the

tank. This loads the sand trap pipe and forces the mud to flow from the rear tank to

the front tank. The de sander pump draws a suction on the forward sand trap, which

keeps the mud and sand moving to the de sander pump with a small amount of mud

flowing from the front tank into the sand trap. Because the mud from the shaker and

de sander cones is deposited into the rear tank, the rear tank will overflow through

the center divider to the front tank. Now, mud in the front tank is clean with the de

sander cones continuously reprocessing the mud so that the mud in the front tank

gets cleaner and cleaner. The suction point for the down hole pump is above the

bottom of the tank there by clean mud is drawn off the top of the front mud tank.

Mud tank.43

De sander

De sander is a centrifuge-type device for removing sand from drilling fluid

in order to prevent abrasion damage to pumps. Also is a hydro

cyclone device that removes large drill solids from the whole mud system.

The desander should be located downstream of the shale shakers and

degassers, but before the desilters or mud cleaners. A volume of mud is

pumped into the wide upper section of the hydrocylone at an angle roughly

tangent to its circumference. As the mud flows around and gradually down

the inside of the cone shape, solids are separated from the liquid by

centrifugal forces. The solids continue around and down until they exit the

bottom of the hydrocyclone (along with small amounts of liquid) and are

discarded. The cleaner and lighter density liquid mud travels up through a

vortex in the center of the hydrocyclone, exits through piping at the top of the

hydrocyclone and is then routed to the mud tanks and the next mud-cleaning

device, usually a desilter. Various size desander and desilter cones are

functionally identical, with the size of the cone determining the size of

particles the device removes from the mud system.

desander.44

De sitter Desilter is a hydrocyclone device that removes large drill solids from the whole mud

system. The desander should be located downstream of the shale shakers and

degassers, but before the desilters or mud cleaners. A volume of mud is pumped into

the wide upper section of the hydro cylone at an angle roughly tangent to its

circumference. As the mud flows around and gradually down the inside of the cone

shape, solids are separated from the liquid by centrifugal forces. The solids continue

around and down until they exit the bottom of the hydro cyclone (along with small

amounts of liquid) and are discarded. The cleaner and lighter density liquid mud

travels up through a vortex in the center of the hydro cyclone, exits through piping at

the top of the hydro cyclone and is then routed to the mud tanks and the next mud-

cleaning device, usually a desilter. Various size desander and desilter cones are

functionally identical, with the size of the cone determining the size of particles the

device removes from the mud system.

desilter.45

Degasser

It is a device that removes air or gases (methane, H2S, CO2 and others) from drilling

liquids. There are two generic types that work by both expanding the size of the gas

bubbles entrained in the mud (by pulling a vacuum on the mud) and by increasing

the surface area available to the mud so that bubbles escape (through the use of

various cascading baffle plates). If the gas content in the mud is high, a mud gas

separator or "poor boy degasser" is used, because it has a higher capacity than

standard degassers and routes the evolved gases away from the rig to a flaring area

complete with an ignition source.

degasser.46

Schematic of the circulating system has been shown in fig40: The drill bit, drill

collar, annulus, drill pipe, kelly and swivel are depicted in the upper right. Drilling

mud flows through the mud return line (center) upon its return to the surface from

the hole to the shale shaker (upper left), then to the adjacent desander, desilter and

degasser back to the mud tank (upper left). Mud passes through the suction line, and

the mud pump (center) circulates the mud through the discharge line (above), the

stand pipe (upper right) through the rotary hose (right) and the swivel (lower right),

back to the kelly and into the drill pipe.

Crain A crane is a machine that is capable of raising and lowering heavy objects and

moving them horizontally. Cranes are distinguished from hoists, which can lift

objects but that cannot move them sideways. Cranes are also distinguished from

conveyors, that lift and move bulk materials, such as grain and coal, in a continuous

process. The word crane is taken from the fact that these machines have a shape

similar to that of the tall, long-necked bird of the same name. Human beings have

used a wide variety of devices to lift heavy objects since ancient times. One of the

earliest versions of the crane to be developed was the shaduf, first used to move

water in Egypt about four thousand years ago. The shaduf consists of a

long, pivoting beam balanced on a vertical support. A heavy weight is attached to

one end of the beam and a bucket to the other. The user pulls the bucket down to the

water supply, fills it, then allows the weight to pull the bucket up. The beam is then

rotated to the desired position and the bucket is emptied. The shaduf is still used in

rural areas of Egypt and India. An important development in crane design occurred

during the Middle Ages, when a horizontal arm known as a jib was added to the

boom. The jib was attached to the boom in a way which allowed it to pivot, allowing

for an increased range of motion. By the sixteenth century, cranes were built with

two treadmills, one on each side of a rotating housing containing the boom. Safety is

the most important factor to be considered during crane manufacturing. The steel

used to make the crane is inspected to ensure that it has no structural flaws that

would weaken the crane. Welds and bolts joints are inspected as well.The United

States government sets specific regulations through the Occupational Safety and

Health Administration that limit the weight that a specific crane is allowed to lift.

The Crane Manufacturers Association of America sets its own safety standards

which exceed those required by the government. Special devices within the crane

prevent the user from attempting to lift a weight heavier than that allowed.A

completed crane is first tested without a weight to ensure that all of its components

operate properly. It is then tested with a weight to ensure that the crane is able to lift

heavy objects without losing stability.Safety ultimately depends on proper use of the

crane. Crane operators must be specially trained, must pass specific tests, and must

be examined for any visual or physical problems. The crane should be inspected each

working shift, with a more thorough inspection of the motor and lifting apparatus on

a monthly basis. Crane operators must be aware of changes in the environment in

order to avoid accidents. For example, cranes should not be used during

very windy conditions.

Every jack up has some carnies, and with regard to their decks, the carnies are

located. Look at the picture to understand the meaning of more important issue about

the deck.

Basic area of a jack up hall.47

The carnies that Located on the jack up, these are used for cargo operations and

retrieval where no shore unloading facilities are available. Most are diesel-hydraulic

or electric-hydraulic.

On the next page there is a diagram showing the most important components of a

pedestal crane which is use on jack up rigs normally.

Components of a cran.48

Modes of operation of a jack up Jack up Units operate in three main modes: transit from one location to another, elevated on its legs,

and jacking up or down between afloat and elevated modes. Each of these modes has specific

precautions and requirements to be followed to ensure smooth operations. A brief discussion of

these modes of operations along with key issues associated with each follows.

Transit from one location to another

The Transit Mode occurs when a Jack up Unit is to be transported from one location

to another. Transit can occur either afloat on the Jack up Unit’s own hull (wet tow),

or with the Jack Up Unit as cargo on the deck of another vessel (dry tow). These

Transit Modes are discussed in more detail below. Main preparations for each

Transit Mode address support of the legs support of the hull, watertight integrity of

the unit, and stowage of cargo and equipment to prevent shifting due to motions.

Though the Unit’s legs must be raised to ensure they clear the seabed during tow, it

is not required that the legs be fully retracted. Allowing part of the legs to be lower

than the hull baseline not only reduces jacking time, but it also reduces leg inertia

loads due to tow motions and increases stability due to decreased wind overturning.

Lowering the legs a small distance may also improve the hydrodynamic flow around

the open leg wells and reduce tow resistance. Whatever the position of the legs

during tow, their structure at the leg/hull interface must be checked to ensure the legs

can withstand the gravity and inertial loads associated with the tow. Field Tow

corresponds to the condition where a Jack Up Unit is afloat on its own hull with its

legs raised, and is moved a relatively short distance to another location. For a short

move, the ability to predict the condition of the weather and sea state is relatively

good. Therefore, steps to prepare the Unit for Field Tow are not as stringent as for a

longer tow. Most Classification Societies define a “Field Tow” as a Tow that does

not take longer than 12 hours, and must satisfy certain requirements with regards to

motion criteria. This motion criterion, expressed as a roll/pitch magnitude at a certain

period, limits the inertial loads on the legs and leg support mechanism. For certain

moves lasting more than 12 hours, a Unit may undertake an Extended Field Tow. An

Extended Field Tow is defined as a Tow where the Unit is always within a 12-hour

Tow of a safe haven, should weather deteriorate. In this

Condition, the Jack up Unit is afloat on its own hull with its legs raised, similar to a

Field Tow. The duration of an Extended Field Tow may be many days. The motion

criterion for an Extended Field Tow is the same as for a Field Tow. The main

preparations for a Unit to undertake an Extended Field Tow are the same as those for

a Field Tow with the additional criteria that the weather is to be carefully monitored

throughout the duration of the tow. A Wet Ocean Tow is defined as an afloat move

lasting more than 12-hours which does not satisfy the requirements of an Extended

Field Tow. In this condition, the Jack Up Unit is afloat on its own hull with its legs

raised as with a Field Tow, but, for many Units, additional precautions must be

made. This is because the motion criteria for a Wet Ocean Tow are more stringent

than for a Field Tow. The additional preparations may include installing additional

leg supports, shortening the leg by cutting or lowering, and securing more equipment

and cargo in and on the hull.

A Dry Ocean Tow is defined as the transportation of a Jack Up Unit on the deck of

another vessel. In this condition, the Jack Up Unit is not afloat, but is secured as

deck cargo. The motion criteria for the Unit are dictated by the motions of the

transportation vessel with the Unit on board. Therefore, the precautions to be taken

with regard to support of the legs must be investigated on a case-by-case basis.

Generally, though, the legs are to be retracted as far as possible into the hull so the

Jack Up hull can be kept as low as practicable to the deck of the transport vessel and

to reduce the amount of cribbing support. The other critical precaution unique to Dry

Ocean Tow is the support of the Jack Up hull. The hull must be supported by

cribbing on strong points (bulkheads) within the hull and in many cases; portions of

the hull overhang the side of the transportation vessel. These overhanging sections

may be exposed to wave impact, putting additional stress on the hull, and if the

overhanging sections include the legs, the resultant bending moment applied to the

hull (and amplified by vessel motions) can be significant. Calculations should be

made to ensure that the hull will not lift off the cribbing with the expected tow

motions.

Arriving on location

Upon completion of the Transit Mode, the Jack Up Unit is said to be in the Arriving

On Location Mode. In this Mode, the Unit is secured from Transit Mode and begins

preparations to Jack Up to the Elevated Mode. Preparations include

removing any wedges in the leg guides, energizing the jacking system, and removing

any leg securing mechanisms installed for the Transit thereby transferring the weight

of the legs to the pinions.

Soft pinning the legs

If an independent leg Jack up Unit is going to be operated next to a Fixed Structure,

or in a difficult area with bottom restrictions, the Jack up Unit will often be

temporarily positioned just away from its final working location. This is called “Soft

Pinning” the legs or “Standing Off” location. This procedure involves lowering one

or more legs until the bottom of the spud can(s) just touches the soil. The purpose of

this is to provide a “Stop” point in the Arriving on Location process. Here, all

preparations can be checked and made for the final approach to the working location.

This includes coordinating with the assisting tugs, running anchor lines to be able to

“winch in” to final location, powering up of positioning thrusters on the Unit (if

fitted), checking the weather forecast for the period of preloading and jacking up,

etc.

FINAL GOING ON LOCATION

Whether a unit stops at a Soft Pin location, or proceeds directly to the final jacking

up location, they will have some means of positioning the unit so that ballasting or

preloading operations prior to jacking up can commence. For an independent leg

Jack up Unit, holding position is accomplished by going on location with all three

legs lowered so the bottom of the spud can is just above the seabed. When the Unit is

positioned at its final location, the legs are lowered until they can hold the rig on

location without the assistance of tugs. Mat type Jack up unit is either held on

location by tugs, or they drop spud piles into the soil. These spud piles, usually

cylindrical piles with concrete fill, hold the Unit on location until the mat can be

ballasted and lowered.

Preload operation

All Jack Up Units must load the soil that supports them to the full load expected to

be exerted on the soil during the most severe condition, usually Storm Survival

Mode. This preloading reduces the likelihood of a foundation shift or failure during a

Storm. The possibility does exist that a soil failure or leg shift may occur during

Preload Operations. To alleviate the potentially catastrophic results of such an

occurrence, the hull is kept as close to the waterline as possible, without incurring

wave impact. Should a soil failure or leg shift occur, the leg that experiences the

failure loses load-carrying capability and rapidly moves downward, bringing the hull

into the water. Some of the load previously carried by the leg experiencing the

failure is transferred to the other legs potentially overloading them. The leg

experiencing the failure will continue to penetrate until either the soil is able to

support the leg, or the hull enters the water to a point where the hull buoyancy will

provide enough support to stop the penetration. As the hull becomes out-of-level, the

legs will experience increased transverse load and bending moment transferred to the

hull mostly by the guide. With the increased guide loads, some braces will

experience large compressive loads. There are detailed procedures to be followed

during such a failure to minimize the structural damage, but these are beyond the

scope of this text. During normal preload operations it is important to keep the

weight of the hull, deck load, and preload as close to the geometric center of the legs

as possible, as this will assure equal loading on all legs. Sometimes, however, single-

leg preloading is desired to increase the maximum footing reaction of any one leg.

This is achieved by selective filling/emptying of preload tanks based on their relative

position to the leg being preloaded. Preload is water taken from the sea and pumped

into tanks within the hull. After the preload is pumped on board, it is held for a

period of time. The Preload Operation is not completed until no settling of the legs

into the soil occurs during the holding period while achieving the target footing

reaction. The amount of preload required depends on the required environmental

reaction and the type of Jack Up Unit. Mat Units normally require little preload.

Four-legged independent Units usually require little or no preload water. This is

because four-legged Units preload two diagonally opposite legs at a time using the

weight of the hull. These Units jack to their preload air gap, then lift two legs

slightly off the seabed. This causes the Unit to settle on the other two legs. The hull

is jacked back up to preload air gap, and the procedure is completed when all four

legs have been preloaded to the target footing reaction and no additional penetration

takes place.

Three-legged independent Units require the most preload water. For Units that

cannot jack with preload, preload water is pumped on board after the hull reaches the

preload air gap. If significant settling occurs, the preload must be dumped before the

hull is jacked to its preload air gap again, and the procedure repeated until no settling

occurs.

For units that can jack with full preload, preload is pumped into the hull while the

hull is still in the water. The hull is then jacked up, usually stopping for a short time

at certain pre-arranged drafts. This continues until the hull is at the preload air gap

and holds the preload for the holding period. Once the preload is held for the

specified time, the preload water is dumped and the Jack Up is ready to be elevated

to the operating air gap.

Jacking to full air gap operations

Once Preload Operations are completed, the unit may be jacked up to its operational

air gap. During these operations it is important to monitor the level of the hull,

elevating system load and characteristics, and for trussed-leg units, Rack Phase

Differential (RPD). All of these must be maintained within design limits. Once the

unit reaches its operational air gap, the jacking system is stopped, the brakes set, and

leg locking systems engaged (if installed). The unit is now ready to begin operations.

Elevated operation condition

When the unit is performing operations, no particular differences exist between the

various types of Units. Likewise, there are no particular cautionary measures to take

other than to operate the unit and its equipment within design limits. For units with

large cantilever reach and high cantilever loads, extra care must be taken to ensure

that the maximum footing reaction does not exceed a specified percentage of the

reaction achieved during preload.

When the unit is performing operations, the weather is to be monitored. If non-

cyclonic storms which exceed design operating condition environment are predicted,

Operations should be stopped and the unit placed in Storm Survival mode. In this

mode, Operations are stopped, equipment and stores secured, and the weather and

watertight enclosures closed. If cyclonic storms are predicted, the same precautions

are taken and personnel evacuated from the unit.

On the below picture, all above mentioned levels about, mode of operation is shown.

Different mode of jack up operation.49

Class approval There are many parties involved in the safety regime for jack ups. These include Shelf States

(national legislation), Flag States (national maritime legislation), Class Societies (class rules), and

International Bodies (international codes, e.g., MODU code, etc.).

Jack ups may not require a flag but are free to move in international waters when carrying flag. In

such case a jack up has to comply with safety regulations of the Maritime Authority in the country

whose flag the unit is flying (the Flag State).

Jack up drilling unit is normally registered with a Flag State Governmental Administration. The role

of the Flag administration is to implement statutory requirements of the government for registering

the unit. Normally, these statutory requirements are derived from internationally agreed regulations

developed by the International Maritime Organization (IMO). Today, Flag Administrations largely

delegate the tasks of verification of compliance with IMO Conventions to classification societies.

Classification societies also issue Loadline, Tonnage and Marpol certificates on behalf of Flag

Administrations. Besides classification and statutory requirements, some governments require

drilling units, regardless of flag, operating in their territorial waters to comply with their own safety

and pollution requirements. A typical example is in the UK. The UK Health and Safety Executive’s

Offshore Division enforces health and safety laws on offshore installations, including jack up

drilling units.

Classification societies are independent, third party organizations that serve as a verification system

for a number of parties who have special interest in the safety and quality of jack ups. These may

include regulatory authorities, insurance underwriters, owners, building yards and sub-contractors,

finance institutions, and charterers.

Classification societies

Classification is a comprehensive verification service providing assurance that a set

of requirements laid down in rules and standards established by the classification

society are met during design and construction and maintained during operation of

the jack up. The rules and standards ensure safety against hazards to the unit,

personnel and the environment.

Each classification society, such as the American Bureau of Shipping (ABS), Det

Norske Veritas (DNV), Lloyds Register (LR), etc., has its own rules for

classification of jack ups. However, many aspects of classification rules of different

classification societies are harmonized through the International Association of

Classification Societies (IACS).

Like ships and other marine structures, jack up drilling units are designed and

constructed to satisfy the rules of classification societies. While classification

certificates issued by a classification society attest to compliance with such Rules,

they also indicate that the unit meets a minimum industry standard for structural and

mechanical fitness. To maintain the unit in class, classification societies require

periodical surveys to check that the unit is adequately maintained. The class

structural scope includes structural strength, materials, welding, fabrication and

corrosion protection for jack up hull, superstructures, legs, spud cans, etc. The rig’s

ultimate strength in different operation modes, like storm survival, elevated

operations, transit, preloading and jacking, etc. are considered. Possible accidental

conditions and fatigue are also examined. Design conditions used as bases for the

strength approval, such as hull weights, water depths, environmental conditions, etc.,

are presented in the rig’s operation manual. Assumed foundation fixities may be

considered and in such cases included in the operation manual. However, foundation

capacity and safety is not part of class structural approval for a jack up rig. It is the

owner’s responsibility to operate the jack up within the conditions used as basis for

class approval, and to confirm that the unit can safely operate at a particular site.

Classification rules (e.g. ABS Rules for Building and Classing Mobile Offshore

Drilling Units) typically address the following areas:

o Materials of construction and fabrication

o Structural integrity

o Afloat stability

o Safety issue such as structural fire protection and means of escape

o Machinery and systems

o Periodical survey

Since jack up units are mobile in nature and can be expected to operate in any part of

the world, the rules for structures are not associated with the environmental,

geotechnical and operational conditions of any specific area. The owner and designer

define the environmental and operational conditions to which the unit has been

designed; these are the design criteria and theoretical operating envelope of the unit.

Designers and owners must assess the desired operating modes and site conditions to

ensure they are within the approved envelope. Classification rules require global

analyses of the primary structure of the unit in the jacked up and afloat modes of

operation. In the transit (afloat) condition leg structures are assumed subjected to

defined roll characteristics and gravity bending moment, with correspondingly more

demanding criteria in severe storm condition. In addition to the global structural

analysis, fatigue analyses are required for classification of all new construction jack

ups. Machinery and systems classification requirements are derived mainly from

rules for ships, except for specific equipment, such as jacking gears, and safety

requirements related to hazards of drilling operations, such as definition of hazardous

areas and the installation of electrical equipment in such areas, high pressure piping

systems related to drilling, fire safety systems, emergency shutdown systems, and

others.

Classification rules impose stability criteria for jack up units in all afloat conditions,

including temporary conditions, such as lowering leg structures. Two sets of criteria

are specified: intact stability and damage stability criteria. While classification of a

jack up unit signifies its compliance with a set of minimum standards (Classification

Rules), it does not imply that the jack up is adequate to operate in any specific area.

In fact, in each case, the owner/operator of the unit should assess the adequacy of the

jack up taking into consideration the water depth, environmental, geotechnical,

seismic and climatic conditions of the area of operation. For this purpose, industry

has developed a standard: SNAME T&R Bulletin 5-5A Guidelines for Site Specific

Assessment of Mobile Drilling Units, which can be used as a guide for performing

such assessments (See 5.2 Site Specific Assessment below).

Site specific assessment

When a jack up is to operate at a particular location, the Shelf State Legislation of

the country in which it is to operate will regulate the activity. Industrialized countries

are normally well regulated and have comprehensive rules for activities on the

continental shelf, while other countries may have less developed regulations and it

will be the oil company / owner’s responsibility to define the documentation basis

for the site assessment. Both shelf state legislation and oil company / owner’s

specification may refer to their own regulations or international guidelines like

“Recommended Practice” (RP) for the Site Specific Assessment of Mobile Jack Up

Units (SNAME Technical and Research Bulletin 5-5A) issued by The Society of

Naval Architects and Marine Engineers (SNAME) for site assessment of jack ups. In

some cases Class Rules and other standards are also considered.

As the name indicates, a Site Specific Assessment is an evaluation of the capability

of a jack up in the elevated condition to meet a set of standards for structural strength

of the jack up and foundation (soil strength of the site) supporting the jack up at a

particular site. In general, the rig owner will be given the environmental conditions

that must be met, along with the soil information needed to perform the assessment.

It is not uncommon for oil companies to have in-house criteria modifying the

SNAME RP to better reflect their risk philosophy. The main objective of the

SNAME RP is to document foundation capacities and global structural strength for

jack up site operations. In cases where the rigs loads, actual environmental condition

and soil conditions fall clearly within the basis for class approval of the structure, it

may be that only foundation capacities need to be considered.

FIELD MOVES

Classification rules require that jack up drilling units meet the intact and damage

stability criteria outlined in the rules. To meet typical intact stability requirements,

jack up units must be capable of withstanding a wind velocity of not less than 36 m/s

(70 kn) for field transit and 51.5 m/s (100 kn) in severe storm (ocean tow)

conditions. Typically leg strength for transit conditions must meet the following:

Field Transit – Leg strength is to be developed to withstand a bending

moment caused by a 6-degree single amplitude roll or pitch at the natural

period of the unit plus 120% of the gravity moment at that angle of

inclination of the legs.

Severe Storm (Ocean Transit) – Legs are to withstand acceleration and

gravity bending moments resulting from the motions in the most severe

anticipated environmental transit conditions, together with wind moments

corresponding to a velocity of not less than 51.5 m/s (100 kn). During dry

tows, classification societies consider the jack up as cargo on the transport

vessel and are not normally requested to review field or ocean transit

arrangements. This is normally carried out by Warranty Surveyors. However

at the completion of an ocean tow, classification societies usually require a

comprehensive survey of the legs, leg to hull connections, the jack house to

hull connections, and any other areas deemed to be highly stressed during the

tow.

Warranty survey companies are often requested to approve wet and dry tow arrangement and

weather predictions of transit routes. Areas that warranty surveyors normally review and approve

for wet tow are: hold down arrangements of cantileversand any cargo on the deck. The warranty

surveyor also ensures that the jack up meets the classification rule requirements for intact and

damage stability. For dry tows warranty survey companies review and approve such things as the

motions of the transportation vessel, cribbing, size of towing tug and towlines, and weather en

route. The weather en route and motions of the jack up and/or towing vessel are carefully monitored

throughout the duration of the tow.

Global pearl (GSF High Island III) Drilling Rig

Arriving late September 2005 in the Gulf of Mexico, Rita sliced through one of the busiest oil

and gas regions as a Category 5 hurricane, bringing 155 mph winds and 60 foot seas. Rita

caused significant damage offshore including:

• 66 platforms destroyed, with 32 more suffering extensive damage.

• 13 MODUs broke their moorings and were set adrift.

• 1 jackup rig was sunk, with 7 jack-ups and 2 semi-subs experiencing extensive damage.

One of those rigs that endure rita was global pearl rig. The High Island was evacuated before

Rita and was also broken off its legs before being set adrift. It sustained major damage,

including the loss of its derrick was found run aground in a self-created trench in shallow

waters off the Louisiana coast. The High Island has gone on to share a similar fate as the

Adriatic VII. Its derrick was not salvaged and is now an underwater obstruction. The legs of

the rig were salvaged in October 2006 by Smit. The hull of the rig was towed back to Port

Arthur shipyard, Texas and sat alongside Adriatic VII. By September 2006, GSF had decided

to dispose of the High Island III and was evaluating whether to sell the remains or declare the

rig a constructive total loss for insurance purposes. On the continuation of this section some

information about global pearl rig has been mentioned.

Global Petrotech Company has planned to repair and upgrade this rig. Main Upgrading plane on the

global pearl can be described as below,the rig was originally designed to work as a drilling in 250 ft

water-depth in hurricane conditions of Gulf of Mexico.

EXISTING SPECS

The objective of this design study is to upgrade following items of the existing design for

the Persian Gulf requirements.

As a result of the upgrades (extra leg length and cantilever modifications ) and additional weights it

is likely that the rig will need sponsons during transit conditions to enable it to meet wet tow"

stability requirements and to keep draft to within reasonable limits. The loading of the cantilever is

converted into loading at the push up and hold down points. The new cantilever loading will be to

would be able to support a maximum of 1000 kips consisting of combined hook+ setback + pipe

rack load. The cantilever would be able to reach 45' aft of the transom and 24 transversely both

ides. With regarding to below diagram, there is free space for new cantilever.

The maximum Spud leg footing reaction = 7100 Kips (Present) The reactions at the spud cans for

the combination of static and environmental cases will be determined to check whether value will

increase for the revised parameters and also With the jacking variable load distribution & new

lightship values including increased cantilever weights, an estimate on the leg reactions at the

jacking cylinder location will be made in order to estimate the jacking system design and working

pressures and loads.

For the repair and up grading of jack up a table has been provided and works and activities in some

important subject have been categorized according to below:

1- Hull related (will be detailed as Series 1000)

2-Legs, Spud cans, Jacking system, RW tower, Cranes (will be detailed as series 2000)

3-Cantilever, skidding, Drilling package HP/LP mud &Well control (will be detailed as series3000)

4-Power Generation & Electrical (will be detailed as series 4000)

5-Instrumentation such as fire & Combustible Gas Detection system (will be detailed as series5000)

6-Machinery & Auxiliary systems such as Potable water tanks (will be detailed as series 6000)

7-Accommodation and HVAC (will be detailed as series 7000)

8-Life saving and other systems (will be detailed as series 8000)

9-Painting (will be detailed as series 9000)

The jack up unit condition is much more complicated than can be describe, because all above

mentioned work has more subtitle as below; and in this section we just try to entitle them.

1000. HULL RELATED

1001. Detail of steel replacement

1100 Hull Accessories

1101 Hinged hatch covers - Cargo Hatches, Preload tank covers

1102 Flat plate Deck Hatch covers

1103 Handrails & Bulwarks

1104 Deck Houses – Paint locker & Deck store, welding shop

1105 Watertight door

1106 Tank vents, sounding tubes & depth indicators (PLT & Mud pit)

1200 Main deck Marine related

1201 Anchor Winches

1202 Anchors & Anchor racks

1203 Fair leads

1204 Smit towing Brackets

1205 Towing Guides (Panama Chocks)

1206 Anchor Buoys & pendant wires

1207 Towing Bridle

1208 Emergency Towing Arrangement

1209 Deck Bollards

2000. LEGS, JACKING SYSTEM, RAW WATER TOWER & CRANE

2100 Leg installation procedure

2200 Spud can installation procedure

2300 Jack house & Guides

2301 Jack Case Structure & Accessories

2302 Jack House Support on Main Deck

2303 Leg Guides – Upper guides and Lower Guides

2304 Walkways & Platforms

2400 Jacking System

2401 Gearboxes & Pinions

2402 Electrical Jacking Motors

2403 Jacking Console

2405 Electrical cables and Junction Boxes

2406 Anode installation plan

2500 Raw Water system (Sea water)

2501 Raw water Tower structure 129 ft

2502 RW Pumps

2503 RW Gearboxes & Motors (2)

2505 Raw water pumps – Electric submersible

2600 DECK CRANES

2601 Port Deck Crane

2602 Starboard Deck Crane

2603 Forward Deck Crane

2604 Electrical & Instrumentation

2605 Crane load testing

3000. Cantilever & longitudinal skidding

3001 Main Cantilever beams

3002 Hold Down & Push-up Structures

3004 Cantilever walkways, staircase & platforms

3005 Cantilever skid rails

3006 V-Door Ramp & Supports

3007 Accumulator platform & Trip tank platform

3010 Longitudinal Skidder Unit Foundation & Supports

3011 Longitudinal Skidder Unit

3020 Sub base Structure

3021 Sub base Structure Walkways, ladders, platforms

3022 Transverse skidder Unit foundations on deck

3025 Drilling Line Reel platform

3026 HP hoses hookup platform

3027 BOP Trolley beams

3100. Drilling Package

3101 Drill floor substructure & rotary beams

3102 Drill floor framing & Setback area

3103 Pollution pan

3104 Draw works shelter

3105 Dog House

3106 Driller's Cabin (Structural & Outfitting)

3107 Snubbing Posts

3108 Walkways, Handrails, Staircases & Ladders

3109 Poor boy degasser

3110 Derrick - Foundation

3120 Hoisting System

3121 Procure & Install Derrick

3122 Procure & Install Crown block

3123 Install Deadline Anchor

3124 Install draw works

3125 Install auxiliary brake – elmagco

3126 Install Rotary table and drive motor

3127 Install travelling Block & Hook

3128 Install Top drive

3129 Install Drill Line Spool

3130 Other Drill Floor Equipment

3131 Drill Floor Winches – Air taggers

3132 Mathey Slick wire line Unit

3133 Iron Roughneck

3134 EZY Torque

3135 Mud Bucket

3136 Power Tongs

3200 HP Mud System related

3201 Mud Pumps Existing Overhaul

3202 3rd Mud pump – Installation related

3203 Mud Pump controls - Local

3204 Mud pump accessories – Pop off valve, oil pump, water pump etc

3205 Supercharging Pumps

3210 HP Mud lines – from MP to Drill floor standpipe

3211 Standpipe Manifold at DF

3300 LP Mud System related

3301 General note related to piping

3305 Mud Pits

3306 Mud pit piping – mixing & transfer

3307 Mud pit mixing & transfer pumps – Suction and discharge

3308 Low Pressure Lines in mud pit area

3310 Mud guns and mud gun lines in mud pit area

3311 Mud Agitators

3312 Mud mixing hopper

3313 Mud Shear system

3314 Mud Pit Level Indicators

3315 Mud Pit pressure control

3400 Mud Return & Mud treatment

3401 Sand trap tanks

3402 Bell nipple, Flow Line – transverse & longitudinal

3405 Shale shakers

3406 De sander, De silter , Mud cleaner

3407 Centrifuge unit

3408 Centrifugal Pumps for above

3409 Mud Degasser – Vacuums type

3500 Well Control & Testing System

3501 Annular Type BOP – Diverter stack 2000 PSI

3502 Annular Type BOP – 13 5/8 inch 5 K Hydril 5000 PSI

3503 Double pipe ram BOP's - 13-5/8 10 K CIW

3504 Mud Cross

3505 Choke & kill line valves

3506 Flexible armored Kill & Choke hoses to BOP

3510 Cellar deck – BOP work deck

3511 Cellar deck – 4 drum air winch

3512 Texas deck - Conductor Support Platform

3513 BOP storage cradles - PORT & STBD

3514 BOP tie down winches

3515 BOP hoists and trolley

3516 Man rider units for BOP work

3517 Trip tank system

3520 Accumulator Unit

3521 Hydraulic control lines to BOP

3522 BOP control panels – Local, Rig floor and TP office

3530 Choke & Kill manifold

3531 Remote control panel for choke

3532 Well Testing

3600 Drilling Instrumentation

4000 POWER SYSTEM & ELECTRICALS

4100 Main Engine Generator Set

4101 Removal of engines

4102 Layout & foundation details for new CAT 3516 B engines

4105 Ventilation – Supply and Exhaust fan

4110 Engine alarm panel

4111 Emergency shut down system

4114 Cold air start compressor & piping

4115 Lube oil pump, piping

4116 Engine waste oil & drain

4117 Exhaust muffler & Piping

4120 Engine cooling system

4121 Engine cooling piping

4122 Engine cooling platform structure

4123 Radiator details

4500 Emergency Power System

4501 Engine D 379 Caterpillar

4502 Alternator Kato 400 KW

4503 Switchboard and MCC

4504 Emergency generator room outfitting

4600 SCR/Switchboard/MCC

4601 General guidelines

4602 Power control room PCR (control cubicles)

4603 Silicon controlled rectifier system SCR

4604 Main distribution system

4605 Distribution switch board

4700 Transformers

4800 Rig Cabling

4801 Specification for power and control cable

4802 Cables for power and lighting circuits

4803 DC power cable

4804 Cables for control Circuit

4806 festoon system to rig floor

4807 cable drags chain system

4808 MCT – multi cable transits

4900 Rig Lighting

4901 Lightning intensity

4902 Navigation light and obstruction light

4903 Heli deck lighting

5000 INSTRUMENTATION & ELECTRONICS

5100 Fire and combustible gas detection system

5200 Fixed fire protection systems – CO2, Foam, Chemical

5300 Public Address and General alarm and telephone system

5400 Control room and radio room equipment

5500 H2S gas detection system

6000 MACHINERY & AUXILLIARY SYSTEMS

6010 Potable Water System

6011 Potable water tanks and tank coating

6012 Potable Water Piping Complete

6013 Potable water heaters

6014 Potable Water UV Sterilizer

6015 Waste heat Water Maker system

6016 Potable water Pressure sets

6020 Drill Water System

6021 Drill water tanks

6022 Drill Water Manifold & Piping Complete

6023 Drill Water Pumps

6030 Bilge System

6031 Bilge Manifold & Piping Complete

6032 Bilge Pumps & Motors

6033 Bilge alarm system

6040 Fire Main Piping System

6041 Fire Pumps

6042 Fire Main Piping Complete

6043 Fire Hose Stations & Boxes

6044 Fire shore connection

6060 Rig Drain & Anti-Pollution System

6061 Rig Drain Piping Complete

6062 Skimmer Tank & System and oily water separator

6065 Sewage waste system & treatment unit

6070 Sea Water System

6071 Sea water Manifold on Deck

6072 Sea water Transfer Pumps

6073 Sea Water Piping Complete

6074 Sea Water Cathodic Protection

6075 Overboard Preload Pump & hook up

6080 Rig Air Systems

6081 Rig Air Compressors

6082 Rig Air Dryer

6083 Air Receivers

6084 Rig Air Piping and accessories

6085 Rig air low pressure alarms

6090 Cementing System

6100 Bulk Mud & Cement System

6101 P-Tanks Bulk Tank

6102 Bulk Mud & Cement Piping Systems

6103 Bulk air pressure reducing station

6110 Fuel Oil System - Diesel

6111 Fuel Oil tanks & day tank

6112 Fuel oil pumps

6113 Fuel oil piping

6114 Fuel oil centrifuges

6120 Dirty oil system

6121 Dirty oil tank

6122 Dirty oil pump

6123 Dirty oil piping

7000 ACCOMMODATION, HEATING, VENTILATION & AIR CONDITIONING (HVAC)

7010 Accommodation Externals

7020 Accommodation Internals

7100 Living Quarters HVAC –HVAC report

7200 Hull Mechanical Ventilation – HVAC report

7500 HELIDECK

7501 Helideck Structure – All steel work

7502 Helideck Safety related

7503 Helideck Landing markings

8000 LIFE SAVING & OTHER SAFETY SYSTEMS – SOLAS REPORT

8100 Lifeboats & Platforms

8101 Lifeboats

8102 Lifeboat launching davits,

8103 Lifeboat Muster areas

8200 Life rafts & launch davit

8300 Other Safety Equipment – Marine related

8400 Fire fighting equipment

8500 Miscellaneous safety equipments

8600 Miscellaneous safety equipments

9000. RIG PAINTING

9100 Hull External

Duty report

I was sent on duty to U.A.E on 6th April to 11th April. On the continuation of negotiation with

companies which had attended to global petrotech tender, I had to visit lamprell company and try to

survey some topics with lamprell employees.

As a result, the main discussed matter is mentioned below.

The quarter's modification has been considered on a minimum work basis with intention to retain

the maximum materials possible. The sub-categories to be discussed in detail as follows.

Architectural General layout modifications:

A segregated AHU room of almost 12 sq.m on each level with provision

for utilities is to be provided centrally on all levels.

A separate AHU for the galley is stipulated as per IACS which is applicable

to GL has to be provided along with another one for the mess room.

Adequate space for fresh air duct to pass through the AHU room has to be

considered.

The roof to accommodate new fresh air handling units, condensing units for

AHU of each level, chiller/ freezer units.

Adequate muster stations to be provided near life boats of capacity 44 man

with minimum area of 3.5×44 sq.m area on both port and starboard in

addition to the davit launched life rafts of same capacity on each side on the

main deck.

2 fire station locations ideally on each side (port and stbd.) as per regulation

are to be provided as per new arrangement.

The laundry to be separated from the change room.

A separate riser location is to be arranged in the new layout.

Galley to be rearranged as per new equipment schedule and new galley

hood location besides the forward bulkhead.

The existing equipments and their model number have been noted. But the

functioning is uncertain. The requirement for new equipments has to be

provided by the client to make the new layout.

Lamprell proposes to add the existing 4 man and toilet space to the existing

mess room and have foldable partitions to separate the senior and junior

mess rooms.

Existing compressor room to be removed and that space can be added on to

the pantry which is currently used as a part of the galley.

New chiller/freezer rooms.

Recreation/gym is to be rearranged as per new layout along with new

furnishings.

Offices/ state rooms in the third level to be rearranged with new

joinery/furnishings/ceiling/flooring are:· Service company office,Company

man office, Company man room with toilet, Sr. Tool pusher office, Tool

pusher room with toilet.

New control/radio room layout to be provided within the existing structure

Fire rating:

Doors used inside the quarters do not show the fire rating. The modified

areas will be provided with fire rated doors as per regulation.

Windows used in modified areas will be fire rated as per regulation.

Existing galley shutters/doors/ bulkheads are to be replaced with new A

rated shutters/doors/ bulkheads.

Tool pusher office may be used as the secondary control station and will

have to be provided with new steel bulkhead and insulation of fire rating as

per regulations.

Curtain plates provided to maintain B class rating in corridors in the

existing condition have to be modified to maintain the fire rating.

Draught stops are to be modified as necessary.

New AHU rooms to be rated to B class rating as per the new layout.

Insulation:

The under deck thermal insulation has to be replaced depending on new

penetrations and damage. The new insulation is 45 kg/m3 50 mm thick

glass wool insulation.

The thermal insulation around areas with layout changes will be required to

be replaced.

Under deck, Bulkhead rating of tool pusher office, emergency generator

room and control house to be ensured by new insulation of adequate fire

rating.(A-60 insulation- 60mm thick 100 kg/m3 Rock wool for bulkheads

and 40mm thick 100 kg/m3 Rock wool wherever required.)

New extensions on the roof for the lost area in the existing accommodation

to be thermally insulated as per fire rating.

Existing roof insulation have to be removed for new Schlumberger unit,

condenser units, fresh air handling units foundations and replaced with

new.

Wall paneling:

AHU room wall paneling to be sandwich panel of B class fire rating.

The existing sandwich panels used are 600mm wide and they can be

replaced with IMAC, Sweden make or similar. This is a long lead item.

They may be replaced with 550 mm wide sandwich panels.

The existing wall panels (almost 20%) to be replaced and layout changes

require further more.

The extension on the port side 3rd level has been done by pro-marine

board. The office and recreation will be rearranged and redone with new

sandwich panels.

The wall panels used in main offices, company man room, tool pusher

room, and control/radio rooms to be replaced.

The new extension on the roof to be furnished with 550 mm sandwich

panels.

Ceiling:

The existing quarters contain 3 kinds of ceilings- Promarine board, gypsum

board in the corridor, mess room, internal stair, galley and third level

extensions and Cermaguard Armstrong (Both 2’×4’ and 2’×2’) in the state

room and offices. The gypsum board cannot be replaced with the same

material as it has no approval from regulations.

The new ceiling tiles used will follow the same pattern with promarine

boards in the corridor. The ceiling grid used in the existing corridor is

damaged and has to be replaced owing to current condition and for running

new ducting and other services.

The rooms in the main deck currently have Cermaguard Armstrong (Both

2’×4’ and 2’×2’). Almost 30% damage for the existing panels and have to

be replaced. The runners are damaged in some areas and have to be

replaced to run the new services.

The lighting and diffuser in the ceiling will have to be modified and the

detail scope as per the respective disciplines.

Smoke detectors used in the existing quarters are battery operated.

New sprinkler system if decided will require nozzles on every room except

for office spaces. Detail to be provided by plumbing discipline.

The new modified mess room shall be provided with Cermaguard

Armstrong (2’×2’) tiles with recessed lighting and diffuser.

The Galley will be provided with SS finish Cermaguard Armstrong (2’×2’)

tiles with recessed lighting and diffuser.

The rest of the rooms have used Cermaguard Armstrong (Both 2’×4’ and

2’×2’). The damaged ones (almost 30%) have to be replaced with the same

make.

New Cermaguard Armstrong (2’×2’) to be used in main offices, company

man room, tool pusher room, extensions on the roof and control/radio

rooms. Flooring/coaming:

Epoxy flooring has been used in the existing quarters.

New epoxy flooring to be used in the modified areas as per the new layout.

Quarry tiles to be used in galley and pantry.

The wet areas require new penetrations and hence change in the flooring.

The wet areas in some of the existing quarters have no coaming. They have

to be provided with new coaming and flooring.

New epoxy flooring with same color pattern to be used in main offices,

mess room, company man room, tool pusher room, extensions on the roof

and control/radio rooms.

Lamprell proposes new flooring in the wet areas and other high traffic

areas.

The rooms are water clogged and that is an indication of leaks. The wet

area flooring have to be removed to determine the state of steel underneath.

The steel decks may have to be replaced depending on the condition.

MAIN DECK & MACHINERY SPACES STRUCTURAL

Raw Water Tower - Client needs to confirm extension of WT - Need

thickness gauging report

Mud Pit Capacity - Client to confirm increase capacity of mud pit

Cement Unit - Need Equipment details. Client to confirm whether the unit

is resting on main deck or will be elevated from main deck.

2. PIPING & PLUMBING

The actual condition of all sounding & vent pipes to be checked when the

tanks are accessible & the scope shall be decided based on that report.

Meanwhile the MTO of entire vent & sounding system shall be taken for

bidding purpose - Client to confirm

The condition of bulk cement piping looks good externally, however

thickness guaging shall be done & scope shall be decided based on that

report. - Meanwhile the MTO of entire Bulk system shall be taken for

bidding pupose - Client to confirm

Client to provide minimum ID required for high pressure cement piping

All fire hose boxes to be replaced

All Koomey unit piping to be replaced, all material will be carbon steel &

suitable for 3000 psi - Client to confirm

Client to provide new trip tank capacity & to confirm the installation of

additional pump.

There is no fire line on cantilever & drill floor area. Fire hydrant is

connected through raw water. Need to provide fire line to meet GL

requirement

As per scope of work only some part of compressed air piping is to be

changed. We recommend to change the entire compressed air piping due

high possibility of internal corrosion as the rig is lying idle for years.

Client to provide raw water pump curve & pressure required at raw water

manifold. This is to asses the existing raw water pump is suitable for

extended raw water tower length & additional raw water requirement

(Deluge etc.)

The actual condition of bilge piping inside & outside tanks to be checked

when the tanks are accessible & the scope shall be decided based on that

inspection & thickness gauging report. Meanwhile the MTO of entire bilge

system shall be taken for bidding purpose - Client to confirm

The actual condition of drill water piping inside & outside tanks to be

checked when the tanks are accessible & the scope shall be decided based

on that inspection & thickness gauging report. Meanwhile the MTO of

entire drill water system shall be taken for bidding purpose - Client to

confirm

The engine cooling system scope is only limited to radiator. This shall be

extended up to engine room as we are changing engine models

The existing sanitary water pressure tank is without pump & connected to

raw water system. We recommend to install 2 nos pumps (1 working & 1

standby) dedicated for this service.

The existing hot water system for accommodation is only form heaters. We

recommend to install a circulating pump in that system.

As informed by you, the thickness gauging for all LPM lines are done but

results were not uniform, Lamprell needs to redo the thickness gauging &

piping replacement scope shall be decided based on that. Meanwhile the

MTO of entire LPM (low pressure mud) system shall be taken for bidding

purpose - Client to confirm

We recommend to replace globe valve in mud pit suction lines by knife

gate valve (Already existing two valves are replaced)

The minimum capacity required for each fire pump to meet helideck & GL

requirement is 172 m3/hr (760 gpm) - Client to confirm if the existing fire

pump meets this requirement.

A booster pump needs to add in the fire line to get the required pressure (7

bar) at helideck.

The fire main header size to be changed to 6" from 5", as for above

mentioned fire pump capacity the flow velocity in 5" Sch. 80 pipe is high

(4.07 m/sec)

3. ELECTRICAL

New water heater to be installed in place of old one

Water heater panel to be relocated to new position at suitable height away

from flanges

Skidding system to be equipped with limit switches, requirement of

additional skidding and transverse motors are subject to study, change can

cause replacement/modification of skidding panel

Booster heater panel located in unsuitable position and polluted by some

leak, to be relocated and overhauled Power connection for new cement unit

to be arranged

Most of main deck/machinery space cabling are old and require

replacement

Most of pushbutton stations at main deck/machinery space are old and

require replacement

Anchor winches junction boxes/MCT's require replacement

Main deck welding workshop no job required

Main deck to be equipped with new sockets (except accommodation)

Main deck lighting to be totally new

Machinery space lighting Option 1) Replacement of light fittings in bad condition, and DB's repair job

Option 2) totally new lighting arrangement, with new DB's

Raw Water Tower: Option1) New cables to be installed instead of existing and those, which missing

Option2) New controls to be provided

Option 3) Elevation Control panel to be modified for case with additional pump