introduction to petroleum engineering - lecture 7

7/27/2019 Introduction to Petroleum Engineering - Lecture 7

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BEng (Hons) Petroleum Engineering

Course:

Introduction To Petroleum Engineering

Instructor

Dr. Tarek Darwich


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Course Outlines: What is Petroleum Engineering?

The Life Cycle of Oil and Gas projects,

Origin, formation and accumulation of Petroleum,

Oil & Gas Exploration,

Appraisal of Oil & Gas Discoveries,

Development of Oil & Gas Discoveries,

Producing Oil & Gas Fields, Transportation of Oil & Gas,

The Petroleum Industry & the Environment,

Petroleum Economics.

I ntroduction to Petroleum Engineer ing

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Weekly News


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Weekly News


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Drilling

Well Profiles


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Typical Drilling Time

Depth Curve


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Main Components of Drilling Rigs


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- Power System

- Hoisting System

- Rotary System

- Circulating System- Well Control and Monitoring System


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Drilling Rig Power System Most power is consumed by:

Hoisting System

Circulation System

Total power requirements 500 to 3000 HP

Diesel engines compose the majority of power sources on rotary rigs.

Natural gas or gasoline engines are getting more popular.

The minimum power requirement is around 10 HP every 100 ft depth


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Drilling Rig Hoisting System Hoisting system is used to lower or

raise the drill string, casing stringand other subsurface equipmentinto or out of the hole.

The principal components are:

Derrick and Substructure

Block and tackle system

Draw works

The Derrick

A structure of steal beams or tubesthat can be completely dismantledand reassembled.

Provides vertical height to raisesections of pipe.

Provides support to the crown block


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http://localhost/var/www/apps/conversion/tmp/scratch_6//upload.wikimedia.org/wikipedia/commons/f/f6/Derrick.JPG


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Drilling Rig Hoisting System The main components of the

Block and Tackle System are:

The Crown Block

The Travelling Block

The Drilling Line

The main function is to providea mechanical advantage whichpermits easier handling of largeloads.

Draw works provide thehoisting and the braking powerrequired to raise or lower theheavy string of pipes.


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Drilling Rig Rotary System Wells are drilled by pipe and bit

rotation.

This system mainly includes thefollowing:

Swivel

Kelly

Rotary Drive

Rotary table

Drill Pipe

Drill Collar

Bit

The swivel supports the weight of thedrill string and permits rotation.


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Drilling Rig Rotary System

The kelly is either square or hexagonalto be gripped easily. It is connected tothe drill pipes. The kelly transmits themotion of the rotary table to the drill

pipes.

Rotary drive provides the power torotate the rotary table.

Rotary table supports the weight of thedrill string and permits rotation.


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Rotary Drilling

Bottom Hole Behaviour


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The Drilling Bit

The drilling bit is the cutting tool whichis made up on the end of the drillstring.

The bit drills through the rock byscraping, chipping, gouging or grinding

the rock at the bottom of the hole.

Drilling fluid is circulated throughpassage ways in the bit to remove thedrilled cuttings.

There are many variations in the designof drill bits.

The bit selected for a particularapplication will depend on theformation being drilled.


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The Drilling Bit

The drilling bit performance is functionof several operating parameters suchas:

The weight on bit (WOB)

Rotations per minutes (RPM)

Mud Properties Hydraulic Efficiency

Three main types of drilling bits:

Drag bits

Roller Cone Bits

Diamond Bits

Drag bits were the first used in rotarydrilling but no longer in common use.


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The Drilling Bit Roller Cone Bits

A roller cone bit is made up of 3 mainparts:

The cones

The bearings

The body of the bit

Each cone has concentric rows of teeththat interfit with the rows of teeth inthe adjacent cones.

The teeth can be made of:

Steel machined in the cone

Tungsten carbide inserts cold-pressedinto holes drilled in the cone.


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A roller cone bit is made up of 3 mainparts:

The cones

The bearings

The body of the bit

Each cone has concentric rows of teeththat interfit with the rows of teeth inthe adjacent cones.

The teeth can be made of:

Steel machined in the cone

Tungsten carbide inserts cold-pressedinto holes drilled in the cone.


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Bits with steel teeth are used when:

spudding in a well,

in a soft formation,

at high rotational speeds and

where bed thickness makes insert bits not

economic.

Bits for soft formations are designed withlong, widely spaced teeth to help penetrate inthe formation and tear off larger cuttings.

The bits for medium and medium-hardformations have more closely spaced teeth.

The tungsten-carbide insert bits are used todrill very hard abrasive formations. These bitsare more expensive.


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The Drilling Bit Diamond Bits

There are 3 types of diamond bits dependingon the nature of the cutting element

With natural diamond

With PDC (polycrystaline diamond compactcutters)

With TSP (with thermally stable polycrystalinediamond compact cutters).

Diamond is the hardest known mineral. Itscompressive strength is approximately80,000 bar (tungsten carbide 50,000 bar andsteel 15,000 bar).


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The Drilling Bit Coring Bits

A coring bit does not drill out the centre of the hole but allows thiscentral portion (the core) to pass through the round opening of thebit and into the core barrel.


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The Drilling Bit Coring Bits


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The Drilling Bit Coring Barrel


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The Drilling Bit Cores


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Bit Selection

The goal of bit selection is to obtain the lowest cost per foot. The cost per foot can be calculated by

using the equation:

Where C is the overall cost per foot, $/ft; Cb is the cost of the bit, $; Cr is the cost of operating the rig

$/hr; tb is the rotating time with bit on bottom, hours; tt is the round trip time, including connection time,

hours; to is the other time, which is not rotating time or trip time, hours; and DD is the total depth as a

given total time, ft.


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The Drill String

The drill string is a assemblage of hollow pipes of circular section,extending from the surface to the bottom of the hole.

It has three functions: It takes the drilling bit to the bottom of the hole, while transmitting its rotation and

its vertical load to it.

It permits the circulation of the drilling fluids to the bottom of the hole

It guides and controls the trajectory of the hole.

Starting from the top, the drill string consists of: A kelly

Drill pipes

Drill Collars

Number of accessory components (e.g. stabilisers, reamers, jars, downhole motors, .)

The bit


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The Drill Pipes

The drill pipes are hollow steel pipes of various types with two tooljoints welded at their ends.


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http://localhost/var/www/apps/conversion/tmp/scratch_6//upload.wikimedia.org/wikipedia/commons/a/a4/Drill_pipe.jpg


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The Drill Pipes Classification

Drill pipes are standardised according to API standards.

They are classified on the basis of their:

length,

outside diameter,

linear weight and their steel grade.

The most common drill pipes are the following:

3.5 (13.3 lb/ft)

4.5 (16.6 lb/ft)

5.0 (19.5 lb/ft)

The grade of the steel is indicated by a letter , indicating the type of material,followed by a number which indicates the minimum yield strength.


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The Tool Joints of Drill pipes

It is the enlarged and threaded ends ofdrillpipes.

These components are separate from thepipe body and welded into the pipe at themanufacturers facilities.

The tool joints provide high-strength,high-pressure threaded connections thatare sufficiently robust to survive the rigorsof drilling and numerous cycles oftightening and loosening at threads.

The tool joints are usually made of steelthat has been treated to a higher strengththan the steel of the tube body.

The tool joints can be threaded a numberof times and they should be protected.


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The Drill Collars

The drill collar is defined as a heavy, tubular connector between drill pipe and a bit.

In drilling operations, the top part of the drill string is in tension while the lower part isin compression; the lengths of the two sections depends on the weight applied on thebit.

Thin-walled drill pipes cannot withstand compression. They may bend and breakunder axial compression. Therefore, the lower part of the drill string is assembled ofheavy pipes.

Drill collars were once a few feet long and weighed 400 or 500 pounds. Today becauseof the increased bit pressure and rapid rotation, collars are made up in 1000-foot

lengths and weigh 50 to 100 pounds.

The most common diameters of drill collars are: 9.5-in, 8-in and 6.5-in.


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Drill Collars & Drill Pipes


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Drill PipesDrill Collars


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The Heavy Weight Drill Pipes

Connection of pipes of very different diameters lead to concentration of tensions andto a fatigue in the areas where cross section varies. This coincides with the location ofthreading which is a weak point.

To avoid the danger of breaks, a short stretch of heavy weight drill pipes is inserted.This allows drill pipes and drill collars to be connected without any abrupt diameter

changes.

The heavy-wall drill pipes are normally made with the same outside diameter as thedrill pipes, but with a smaller inside diameter.

In practice, they are drill pipes with thick walls, having a linear weight two or threetimes greater.


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Drill String Accessory Equipment

The drill string is very often fitted with accessory items which serve to resolvetechnical problems due to the wide variety of drilling conditions.

The most common accessory items of equipment are stabilisers,reamers,jars andshock-absorbers.

Stabilisers are placed along the bottom hole assembly (BHA), in between the drillcollars, to make the string more rigid in the presence of the instability due tocombined compressive, buckling and bending stresses.

Stabilizers are fundamental for controlling the borehole trajectory both in vertical andin directional wells.


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Stabilizers consist of a body to which rib blades are applied, expanding the outsidediameter of the tool to the nominal diameter of the bit.

By changing the composition of the BHA, and in particular the positioning of thestabilizers, the mechanical behaviour of the drill string can be varied, which is useful incontrolling the directional drilling operations.


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Reamers are special stabilisers with roller cuttersinstead of blades.

Mounted on the rollers, there are usually 3 to 6 steelcutters or tungsten carbide inserts.

Reamers serve the purpose of reaming wall of thehole, taking it to the nominal diameter of the bit.

Eliminating the small variations in diameter means anelimination of any possible stepped profile that mightbe in the hole, which could make:

the application of the weight on the bit uncertainor

cause problems with running-in the casing.

Reamers are used chiefly in drilling through streaks ofhard and abrasive


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Jars are mechanical devices used downhole to deliver an impact load to anotherdownhole component, especially when that component is stuck.

There are two primary types, hydraulic and mechanical jars. While their respectivedesigns are quite different, their operation is the same.

Energy is stored in the drillstring and suddenly released by the jar when it fires.

Shock Absorbers is a device placed above the bit to reduce the axial vibrationsgenerated during drilling, which are harmful for both the bit and the drill pipes.

These devices are necessary when the vibrations are strong enough to be visible at thesurface.

In deep wells, the vibrations might not be visible at the surface. In this case othersignals are observed, such as slow penetration rate and a particular bit wear pattern.


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Drill String Specification in the well Programme


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Drill String Useful Links


- DrillingGood & short overview

- http://www.youtube.com/watch?v=nlSKA7PkSzo

- Drill Collars:

- http://www.youtube.com/watch?v=g1LE3IMAfY8

- Openhole Fishing:- http://www.youtube.com/watch?v=7-WqVgksKtk

- Chesapeak Drilling

- http://www.youtube.com/watch?v=fBQCQ6HL2Yw&feature=
http://www.youtube.com/watch?v=g1LE3IMAfY8http://www.youtube.com/watch?v=7-WqVgksKtkhttp://www.youtube.com/watch?v=fBQCQ6HL2Yw&feature=endscreenhttp://www.youtube.com/watch?v=fBQCQ6HL2Yw&feature=endscreenhttp://www.youtube.com/watch?v=fBQCQ6HL2Yw&feature=endscreenhttp://www.youtube.com/watch?v=7-WqVgksKtkhttp://www.youtube.com/watch?v=7-WqVgksKtkhttp://www.youtube.com/watch?v=7-WqVgksKtkhttp://www.youtube.com/watch?v=g1LE3IMAfY8

introduction to petroleum engineering - lecture 7

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