Rig componentsThe most important rig components include:

1. Engines;

2. Derrick and substructure;

3. Hoisting equipment( hoisting element)

4. Rotary equipment;

5. Mud pumps;

6. And blowout preventers (BOPS).

The drawworks is the key component of the drilling rig. Its complete tasks in the whole drilling operation: making round trip-tripping in and tripping out, handling downhole accidents, driving the rotary table to make up and break out and performing any other auxiliary operation. The drawworks is furnished with roller bearings and alloy steel shafts.    pressure lubricated chains at both high speed and low speed ends, ventilated type air-tube clutches are fitted. The brake rim is cooled forcefully by the circulating water, the rim surface is medium frequency induction hardened, having the good abrasion resistance and the long service life.

Transmission of the developed power to various parts of the rig is achieved either mechanically or electrically. In mechanical transmission, the power developed by each engine is gathered in a single arrangement, termed the compound. The compound delivers the engines power to draw-works and rotary table through roller chains and sprockets. In mechanical transmission, rig pumps are powered by the used of large belts.

In electrical transmission, diesel engines are mounted on the ground some distance away from the rig and are used to drive large electric generators. The generators produce electricity that is sent through cables to electric motors attached directly to draw-works, rotary table and mud pump.

Derrick and substructure A derrick is a four–side structure of sufficient height and strength to

allow the hoisting (lowering and raising) of equipment in and out of the well, it also provides a working place for the derrick man during tripping operations. The substructure provides support for the derrick, draw-works and drill string.

Power System

Hoisting equipmentHoisting equipments includes 1. Drawworks2. Hoisting tackle (tackle systems);3. Wire line

Draw-workThe draw-work is the hoisting mechanism on the drilling rig

enabling heavy loads to be raised or lowered by means of wire rope wound on a drum. The draw work also enable the driller, through the catheads, to makes or break drill pipe, drill collars and others connections equipments.

Hoisting tackle There are two blocks crown block and traveling block. The

crown block is static and rests at the top of the derrick, the traveling block move up and down the derrick during making/breaking of drilling joint’s block has a number of pulleys. The drilling line is wound a number of times on each block, the end of drilling line coming out of the crown block clamped to a dead line anchor underneath the derrick .

Drilling line

Power System• The overall efficiency of power generating systems may be defined as

• where Po is the output power and Pi is the input power. The output power of an engine is generally expressed as a function of the engine rotary speed, N, and the output torque, T

• where Po is in HP, T is in ft-lbs, and N is in RPM.

• The input power is expressed in terms of the rate of fuel consumption, Qf, and the fuel heating value, H

• where Pi is in HP, Qf is in lb/hr, and H is in BTU/lb.

Efficiency of

i

PE

P

2

33000o

T NP

2545f

i

Q HP

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Example 1.1:

A drilling rig has three diesel engines for generating rig power requirement. Determine the total daily fuel consumption for an average engine running speed of 900 rpm, average output torque of 1610 ft-lb and engine efficiency of 40 %. The heating value of diesel oil is 19000 BTU/lb, and the weight of the diesel is 7.2 ppg.

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A Rotary Rig Hoisting System• The primary function of the hoisting system in rotary drilling is to

hoist the drill and casing strings during drilling and casing operations, respectively

• Its major components consist of the draw-works, crown block, traveling block, hook, drilling (wire) line and the elevator.

This is a more accurate drawing of the hoisting system. The drum is located inside the drawworks, and is the spool that the drill line is wound up on when raising the traveling block. The crown block is located at the top of the derrick (the crown) and the drill line is strung between the crown block and the traveling block. On the bottom of the traveling block is the hook, where the drillstring, casing, etc. is suspended. The end of the drill line that is wound up on the drawworks is called the fast line, the other end is attached to the deadline anchor on one of the derrick legs, and is called the dead line. Extra drill line is stored on a storage reel.

Load on Derrick

Force Diagram (free body diagram ) of the blocks and drilling line systems. The efficiency of the blocks and drilling line systems can be measured by

hF

Efficiency of

i

PE

P

where Po is the output power and Pi is the input power. The output power is defined as

where Fh is the hook load, and vtb is the traveling block velocity. Similarly, the input power is given by

where Ffp is the load in fast line, and vfp is the fast line speed.

o h tbP F v

i fp fpP F v

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• The magnitude of Ffp depends on the number of lines strung between the crown block and the traveling block, and the frictional forces induced between the contact surfaces of the lines and block sheaves. Utilizing these equations yields

h tbf

fp fp

F vE

F v

Efficiency factors accepted in the industry for block and tackle system of various number of lines are presented in the following table:

It can be easily established thatfp

tb

vv

N

where N is the number of lines strung between the crown block and traveling block.

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Load on Derrick• Therefore,

• If the load, Fh, is being hosted by pulling on the fast line, the friction in the sheaves is resisting the motion of the fast line. Therefore, the tension in the dead line, Fsp, is

hfp

f

FF

N E

hsp

FF

N

The load applied to the derrick, Fd, is the sum of the hook load, Fh, the tension in the dead line, Fsp, and the tension in the fast line, Ffp,

d h sp fpF F F F

1 f fh hd h h

f f

E N EF FF F F

N N E N E

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Example 1.2

A rig must hoist a load of 300,000 lbf. The draw-works can provide an input power to the block and tackle system as high as 500 hp. Eight lines are strung between the crown block and traveling block. Calculate

1. The static tension in the fast line when upward motion is impending,

2. the maximum hoisting speed,

3. the actual derrick load,

4. the maximum equivalent derrick load,

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Ton-Mile Calculations• The API recommends the use of “ton-mile” concept to evaluate

drilling line . Drilling Ton-Mile is the work of drilling line that is commonly measured as the cumulative of the load lifted in tons and the distance lifted or lowered in miles.

• Because of the heavy loads encountered during tripping in-out and drilling operations, the drilling line wears out especially from the contact points, i.e., drum and blocks. therefore, drilling contractors must cut old section and replace with new section of drilling line at specific period based on ton mile calculation.

1 2

14

2Ton-Mile

10560000

st mD L D W D M C C

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• where D is the hole depth in ft, Lst is the length of one stand of pipe in ft, Wm is the weight per foot of drillpipe in the mud in lb/ft, M is the weight of block, hook, elevator, etc in lbs, and C1 and C2 are the difference of the weight of 540 ft of drill collar and drillpipe in mud in lbs.

• As a rule of thumb, • 18 ft of drilling line is slipped from the storage reel to the drum after

every 200 ton-miles,• 72 ft of drilling line should be removed from the drum after every 800

ton-miles.

Example 1.3

A drilling is on progress at a depth of 5000 ft. Weight of the drillpipe and drill collar in mud are 16.1 lb and 75 lb, respectively. The length of one stand of pipe is given as 95 ft. Total weight on the pulley is 15000 lb. Conduct the ton-mile calculation for this system.

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Minimum Length of Drilling Line Required

• For practical purposes, the following equation is usually preferred for estimating the minimum required drilling line:

• where Lwire is the minimum required drilling line length in ft, Lderrick is the height of the derrick in ft, N is the number of lines strung, and Lrope on drum is the length of the rope on the drum in ft.

Example 1.4• Using a 176 ft derrick, 8 number of line strung, 300 ft of rope on drum

at lower pick, estimate the minimum required length of drilling line for this rig.

wire derrick rope on drum2L L N L

FLUID CIRCULATION SYSTEM

The main components of the system include 1) mud pumps/air compressors, 2) high pressure surface connections3) drillstring4) drill bit 5) return annulus 6) mud pits 7) mud treatment equipment.

The swivel is installed above the Kelly, and its main function is to prevent the rotary motion of the Kelly from being transferred to the drilling line. This is achieved by the rotation of the lower half of the swivel on a set of heavy-duty roller bearings. As the swivel has carry the entire weight of the drilling strings, it must be ruggedly constructed and of the same rating as the traveling block.

The swivel also allows mud to be pumped through the Kelly through a side attachment, described as a gooseneck, a flexible rotary hose, connects with the swivel through the gooseneck. The rotary hose is connected through a standpipe and surface lines to the mud pumps.

Mud pump Mud pumps are used to circulate huge quantities of drilling

mud down many thousands of feet of drilling strings through small nozzles size of the drilling bit. The pump must, therefore, produce pressure to overcome the frictional or drag forces to move drilling mud. Mud pumps are available in two types:

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Pumps in common use today are duplex or triplex pumps depending on whether they consist of two or three cylinder (liners ) respectively.

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• Pumps which move fluid on the forward stroke only are called single-acting.

• Those which move fluid on both forward and backward strokes are called double-acting.

• In common field usage, the terms cycle and stroke often are used to refer to one complete pump revolution.

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• The theoretical volume of fluid being displaced by the pump having Nc liners can be easily formulated from the figure shown above, and is given by

• for single-acting pumps, and

2

4t L s cV D L N

2 224t L r s cV D D L N

• for double-acting pumps where Vt is the volume of fluid displaced, DL is the liner diameter, Dr is the rod diameter, Ls is the piston stroke (length stroke), and Nc is the number of cylinders where for duplex pumps and for triplex pumps.

• The volumetric efficiency of the pump can be defined as

a av

t t

V QE

V Q

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• where Va is the actual fluid displaced by the pump or the pump factor and Q’s refer the volume of fluid displaced per unit time.

• For a given pump delivery pressure, P, at a corresponding flow rate, Q, the hydraulic power of the pump is given by

• where HHP is the pump hydraulic horsepower in HP, P is in psi, and Q is in gpm.

Example 1.4

A double-acting duplex pump, 2.5in rod, 20in stroke, is to be operated at 60 strokes/min. For drilling down to 10000 ft. The maximum available pump hydraulic horsepower is 1360 HP with an efficiency of 90%. For optimum hydraulics, the pump delivery pressure is recommended to be 3423psi. Determine the liner size to be used.

1714HP

PQH

2. 10. 2012

Quiz 1: A single-acting pump, 2.5in rod, 20in stroke, is to be operated

at 60 strokes/min. For drilling down to 10000 ft. The maximum

available pump hydraulic horsepower is 1360 HP with an efficiency

of 90%. For optimum hydraulics, the pump delivery pressure is

recommended to be 3423psi. Determine the liner size to be used.

Quiz 2: Determine the fuel consumption for the mentioned above

pump.

H.W: As engineer PLS, sketch the drilling site construction plan

discussing all the quality assurance issues.

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ROTARY SYSTEM• The rotary system includes all of the rig components which are used

to achieve bit rotation. • These are Swivel, Rotary table and rotary bushing, Kelly ,And Kelly

bushing drive, drillpipe, drill collar.

Rotary table and master bushing: The main function of the rotary table is to transfer rotary motion through a master bushing to Kelly , to drilling strings and eventually , to the drill bit. Rotation of drill bit is necessary for rock breakage and in turn for making hole. Besides transferring rotation to the Kelly, the master bushing also acts as a seat for slips.Slips: are wedge-shaped devices, lined with tooth –like gripping elements,. They are needed to hold the drilling string suspended in the hole when adding or breaking joints of the drilling strings.Power required fore the rotation of the table is transmitted from the main rig engines through a chain drive from the compound , as in mechanical rigs or rotary table is independently powered through a cable connected to a motor attached to the rotary table. The Kelly has hexagonal or square shape, and its main function is to transfer motion to the drilling string when the Kelly bushing is engaged with the master rotary bushing. The Kelly also as a medium for transporting mud down to the drilling string and to the bit. During tripping the Kelly rests in a side hole, called a rathole Swivel

Drilling stringsThe drilling string consists of1. drill pipe;2. drill collars3. Accessories 4. Drill bit.

The drill pipe serves as a medium for the transmission of rotary motion to the bit and also acts as a passage for mud.

Drill collars are heavy-duty pipes with large weight on the bit during drilling operation. The remainder is used to keep the drill pipe in tension , thereby avoiding buckling of the pipes.

Accessories normally include: HWDP, stabilizers and shock subs.HWDP is used to ensure that the drill pipe is always kept in tension. a stabilizer is a special tool with an outside diameter OD close the hole diameter. The main function of a stabilizer to prevent buckling (bending) of drill collars and to control the drilling string direction. Stabilizers: are run between drill collars and drill bit.A shock sub is included in bottomhole assembly to absorb shocks when he bit bounces off hard formations, thereby protecting the drilling strings and surface equipment from damaging effects of bit vibrations.

the drill bit is the main component of the drilling strings and is used to cut the rock for the purpose of making hole. Drilling bit can have one cutting head , as in diamond and polycrystalline diamond compact bits

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Well Control System• The primary function of the well control system is to prevent the uncon trolled

flow of formation fluids from the wellbore. • The system requirements are to permit:

shutting in the well at the surface, controlling the removal of formation fluids from the wellbore, pumping higher density mud into the hole, stripping the drillpipe into or out of the hole.

• The basic components of the well control system are the following: Blow out preventer stack (BOP)

Annular preventers Ram preventers Spools Internal preventers

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Casing head Flow and choke line fittings Kill lines and connections Mud and gas handling facilities Accumulators

A blowout can be defined as an uncontrolled influx of formation fluid which has sufficient pressure to cause damage to rig equipment and injury to rig personnel.

Blowout preventers ( BOPs) are devices placed on top of the well to provide a line of defense against possible well kicks which may produced dangerously high pressures within the annulus of the well.

The number, size and rating of BOPs used will depend on the depth of the well and the maximum anticipated formation pressures. In general, there are two types of BOP: annular and ram types.

A well kick is an unwanted flow of formation fluids into the wellbore hole which may develop into a blowout.Blowout preventers are valves that can be closed any time a well kick is detected.

Blowout preventers are of three types1. Annular preventers are manufactured to close around any size

or shape of pipe run in the hole and are normally closed when the well is threatened by a kick.

2. Pipe rams.

3. Blind and shear rams. Blind rams are designed to close the bore when no drilling string or casing is present. A shear ram is a type of blind ram which has the ability to cut pipe and pack off an open hole.

Annular BOPS are designed to shut off around any size and shape of equipment run through the hole. Thus, annular preventers can close around drill pipe, drill collars and casing, and can also pack off open hole. Annular preventer are, therefore, the wells master valve and is normally closed first in the event of a well kick.

The main components of an annular preventer include: steel body;operating piston;closing chambers;a ring of reinforced synthetic rubber having a high tensile strength.

Annular preventers can only be closed hydraulically by directing fluid under pressure to the operating cylinder through the closing chamber.

Pipe rams are designed to close around a particular size of drillpipe, tubing or casing. The pack off is provided by two steel ram blocks containing semi-circular opening with each ram being fitted with a two piece rubber seal.

The semi-circular openings can seal around the outside diameter of the drillpipe, tubing drill collar, Kelly or casing, depending on the size of the rams chosen. Pipe rams are designed to center the pipe in the hole before providing a complete pack off. Pipe rams can be closed manually or hydraulically to seal off the annular space below them.

Hydraulically –operated pipe rams can be closed from the drillers console on the rig floor or remotely from a position on the ground some distance away from the rig floor.

The increased pressure energizes the packer rubbers, allowing them to flow around the pipe and provide a complete pack-off. Most pipe rams can be closed by hydraulic pressure in the range 500-5000psi.

Pipe rams are designed to be changed easily and have the

ability to direct hole pressures to the back of the preventer, to maintain the seal in the event of hydraulic pressure loss.

Blind rams are similar to pipe rams. Except that packers are replaced by ones that have no cutouts in the rubber. They are designed to seal off the bore when no drilling string or casing is present.

Shear rams are a type of blind ram that can cut the pipe and seal off the open hole. Most shear rams require 3000 psi to cut pipe.

The BOPs control systemThe main components of the control system include:

an accumulator bank;charging pumps;a fluid reservoir; anda manifold for directing the fluid to the preventer.

An accumulator is a high –pressure cylinder containing nitrogen gas and hydraulic fluid.

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Data Acquisition and Monitoring System

• The parameters which are of prime concern are the following:

Drilling rate Hook load Hole depth Pump pressure Flow rate Torque Rotary speed Mud density, temperature, salinity and flow properties Mud tank level Pump strokes Weight on bit Hoisting speed