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Drilling Engineering 1 Course (1st Ed.)

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http://www.about.me/AlamiNia

mailto:[email protected]

http://www.about.me/AlamiNia

1. Introduction

2. Personnel at Rig Site

3. Rotary Drilling System

4. Power System

2 drilling goals

to build the well according to its purpose and in a safe manner

(i.e, avoiding personal injuries

and avoiding technical problems)

to complete it with minimum costThereto the overall costs of the well during its lifetime in

conjunction with the field development aspects shall be minimized.

2013H. AlamiNia Drilling Engineering 1 Course: 4

Parameters

The overall cost minimization, or optimization, may influence the location from where the well is drilled,

(e.g., an extended reach onshore or above reservoir offshore),

the drilling technology applied,(e.g., conventional or slim–hole drilling, overbalanced or

underbalanced, vertical or horizontal, etc),

and which evaluation procedures are run to gather subsurface information to optimize future wells.


drilling technologies

To build a hole, different drilling technologies have been invented:Percussion drilling

Cable drilling “Pennsylvanian drilling” Drillstring

• With mud Quick percussion drilling• Without mud “Canadian drilling”

Rotating drilling (Will be discussed exclusively) Full cross-section drilling

• Surface driveno Rotary bito Rotary nozzle

• Subsurface driveno Turbine drillingo Positive displacement motor drillingo Electro motor drilling

Annular drilling Diamond coring Shot drilling


drilling technologies (Cont.)

Special techniquesAbrasive jet drilling

Cavitating jet drilling

Electric arc and plasma drilling

Electric beam drilling

Electric disintegration drilling

Explosive drilling

Flame jet drilling

Implosion drilling

Laser drilling

REAM drilling

Replaceable cutterhead drilling

Rocket exhaust drilling

Spark drilling

Subterrene drilling

Terra drilling

Thermal-mechanical drilling

Thermocorer drilling


Rig Classification

Rotary Drilling Rigs

Land

Mobile

JackknifePortable

Mast

Conventional

Marine

Bottom Supported

Platform

Self Contained

Tendered

Barge

Jack-Up Submersible

Floating

Drill ShipSemi

Submersible

Caisson Vessel

Tension Leg


Land: Mobile Rigs

Jackknife rig Portable mast2013H. AlamiNia Drilling Engineering 1 Course: 9

Marine: Bottom Supported Platform rigs

Self Contained Tendered2013H. AlamiNia Drilling Engineering 1 Course: 10

Marine: Other Bottom Supported rigs


A Jack–Up rig A submersible platform

A cantilever rig on a barge

Marine: Floating rigs


Caisson vessel

(also called

sparbuoy) and Diagram of a spar–buoy

A tension–

leg platform

A drill–ship Semi–

submersible

vessel

Personnels

People directly involved in drilling a well are employed either by the operating company,

the drilling contractor,

or one of the service and supply companies

The operating company is the owner of the lease/block and principal user of the services provided by the drilling contractor and the different service companies.


Tasks

Since drilling contractors are companies that perform the actual drilling of the well, their main job is to drill a hole to the depth/location and specifications set by the operator.

Along with hiring a drilling contractor, the operator usually employs various service and supply companies to perform logging,

cementing,

or any other special operations, including maintaining the drilling fluid in its planed condition.


drilling crews

Most drilling crews consist of a tool pusher, a driller, a derrickman, a mud logger, and two or three rotary helpers

(also called floormen or roughnecks).

Along with this basic crew configuration the operator sends usually a representative, calledcompany man to the rig.

For offshore operations the crews usually consist of many more employees.


crew requirements

Tool Pusher: supervises all drilling operations and is the leading man of the drilling

contractor on location.

Company Man: The company man is in direct charge of all company’s activities on the

rig site. He is responsible for the drilling strategy as well as the supplies and

services in need. His decisions directly effect the progress of the well.

Driller: The driller operates the drilling machinery on the rig floor and is the

overall supervisor of all floormen. He reports directly to the tool pusher and is the person who is most

closely involved in the drilling process. He operates, from his position at the control console, the rig floor

brakes, switches, levers, and all other related controls that influence the drilling parameters.

In case of a kick he is the first person to take action by moving the bit off bottom and closing the BOP.


crew requirements (Cont.)

Derrick Man: The derrickman works on the so–called monkeyboard, a small platform

up in the derrick, usually about 90 ft above the rotary table. When a connection is made or during tripping operations he is handling and

guiding the upper end of the pipe. During drilling operations the derrickman is responsible for maintaining and

repairing the pumps and other equipment as well as keeping tabs on the drilling fluid.

Floormen: During tripping, the rotary helpers are responsible for handling the

lower end of the drill pipe as well as operating tongs and wrenches to make or break up a connection.

During other times, they also maintain equipment, keep it clean, do painting and in general help where ever help is needed.

Mud Engineer, Mud Logger: The service company who provides the mud almost always sends a mud

engineer and a mud logger to the rig site. They are constantly responsible for logging what is happening in the hole as well as maintaining the proper mud conditions.


Well Classifications

According to a wells final depth, it can be classified into:Shallow well: < 2000m

Conventional well: 2 000m – 3500m

Deep well: 3500m – 5000m

Ultra deep well: > 5 000m

With the help of advanced technologies in MWD/LWD and extended reach drilling techniques, horizontal departures of more than10000m are possible today.


Typical rig components


rig systems

For all rigs, the depth of the planned well determines basic rig requirements. The most important rig systems are:Power system,

Hoisting system,

Drilling fluid circulation system,

Rotary system,

Derrick and substructure,

Well control system,

Well monitoring system


drilling process

In rotary drilling, the rock is destroyed by the action of rotation and axial force applied to a drilling bit.

The drilling bit is located at the end of a drill string which is composed of drill pipes (also called joints or singles), drill collars, and other specialized drilling tools.Drill collars are thick walled tubes responsible for

applying the axial force at the bit.

Rotation at the bit is usually obtained by rotating the whole drill string from the surface.


A simplified drillstring

The lower portion of the drill string, composed of drill collars

and specialized drilling tools,

are called bottom hole assembly (BHA).


drilling process (Cont.)

A large variety of bit models and designs are available in industry. The choice of the right bit, based on the characteristics of the formations to

be drilled, and the right parameters (weight on bit and rotary speed)

are the two most basic problems the drilling engineer faces during drilling planning and drilling operation.The cuttings are lifted to the surface by the drilling

fluid. At the surface, the cuttings are separated from the

drilling fluid by several solid removal equipment. Drilling mud is picked up by the system of pumps and

pumped again down the hole.


connection

As drilling progresses, new joints are added to the top of the drill string increasing its length, in an operation called connection.

A pipe slips is used to transfer the weight of the drillstring from the hook to the master bushing.


round trip

As the bit gets dull, a round trip is performed to bring the dull bit to the surface and replace it by a new one.

A round trip is performed also to change the BHA.

The drillstring is also removed to run a casing string. The operation is done by removing stands of two (“doubles”), three (“thribbles”) or even four (“fourbles”) joints connected, and stacking them upright in the rig.


Removing one stand of drillstring


wiper trip

Sometimes the drillstring is not completely run out of the hole.

It is just lifted up to the top of the open-hole section and then lowered back again while continuously circulating with drilling mud. Such a trip, called wiper trip,

is carried out to clean the hole from remaining cuttings that may have settled along the open–hole section.


power supply

The power system of a rotary drilling rig has to supply power to all the other systems.

In addition, the system must provide power for pumps in general, rig light, air compressors, etc.

Since the largest power consumers on a rotary drilling rig are the hoisting, the circulation system, and the rotary system, these components determine mainly the total power requirements.

During typical drilling operations, the hoisting and the rotary systems are not operated at the same time. Therefore the same engines can be used to perform both functions.

power system

Drilling rig power systems are classified as direct drive type (internal combustion engines supply

mechanical power to the rig ) and electric type.

In both cases, the sources of energy are diesel fueled engines. Most rigs use one to three engines to power the

drawworks and rotary table. The engines are usually rated between 400 hp and 800

hp. As guideline, power requirements for most onshore rigs

are between 1,000 to 3,000 hp. Offshore rigs in general use much more power.


power system performance

The performance of a rig power system is characterized by the output horsepower,

torque,

and fuel consumption for various engine speeds.

These three parameters are related by the efficiency of each system.


energy consumption by the engines

Heating values of fuels

The energy consumed by the engines comes from burning fuels.

The engine transforms the chemical energy of the fuel into work. No engine can transform totally the chemical

energy into work. Most of the energy that enters the engine is

lost as heat.

The thermal efficiency Et of a machine is defined as the ratio of the work W generated to the chemical energy consumed

to perform this calculation, we must use the same units both to the work and to the chemical energy.

1 BTU = 778.17 lbf/ft,


Fuel TypeHeating

Value(BTU/lbm)

Density(lbm/gal)

Diesel 19000 7.2

Gasoline 20000 6.6

Butane (liquid)

21000 4.7

Methane (gas)

24000 –

thermal efficiency

Engines are normally rated by the power P they can deliver at a given working regime. Power if defined as the rate work is performed, that is work

per unit of time. If ˙Q is the rate of chemical energy consumed by the machine

(chemical energy per unit of time), we can rewrite the expression for the thermal efficiency as:

To calculate ˙Q we need to know the type of fuel and the rate of fuel consumption in mass per unit time.(Consumption of gaseous fuels is normally given in mass per

unit time, but consumption for liquid fuels is normally given in volume per unit time. In the latter, we need to know the density of the fluid.)


output power

A system produces mechanical work when the sole result of the process could be the raising of a weight (most time limited by its efficiency).

where P is power, and v the velocity (assuming F constant).

When a rotating machine is operating (an internal combustion engine or an electrical motor, for example), we cannot measure its power, but we can measure its rotating speed (normally in RPM) and the torque at the shaft. This is normally performed in a machine called dynamometer.


output power

The expression relating power to angular velocity and torque is:

Where omega is the angular velocity (in radians per unit of time) and T is the torque.

A common unit of power is the hp (horse power). One hp is the power required to raise a weight of 33,000 lbf by one foot in one minute:


output power

For T in ft lbf and N in RPM we have:

that is


mechanical horsepower Correction

When the rig is operated at environments with non–standard temperatures (85F) or at high altitudes, the mechanical horsepower requirements have to be corrected. The correction should follow the American Petroleum

Institute (API) standard 7B-llC:Deduction of 3% of the standard brake horsepower for each

1000 ft of altitude above mean sea level.

Deduction of 1% of the standard brake horsepower for each 10F rise or fall in temperature above or below 85F.


Calculation of the output power and the overall efficiency

A diesel engine gives an output torque of 1740 ft lbf at an engine speed of 1200 RPM. If the fuel consumption rate was 31.5 gal/hr, what is the output power and the overall efficiency of the engine.

Solution:

The power delivered at the given regime is:

Diesel is consumed at 31.5 gal/hr. From Table we have:

Converting to hp, results in:

The thermal efficiency is:
