DRILLING TECHNIQUE -...

RudarskoRudarsko--geologeološškoko--naftni fakultetnaftni fakultet

DRILLING TECHNIQUEDRILLING TECHNIQUE

Prof. dr. Davorin MatanovićProf. dr. Davorin Matanović

2RudarskoRudarsko--geologeološškoko--naftni fakultetnaftni fakultet

Drilling rig

• The purpose of drilling rig is-to enable drilling the hole.

•The difference to stationary facilities is that such rigs are mobile, because they have to be moved frequently.

•That requirement can not limit the ability of the rig to drill desired hole.


Drilling rigCROWN BLOCK

WIRE ROPE

TRAVELING BLOCK

HOOK

SWIVEL

ROTARY TABLE

DRAWWORK AND BRAKES

MUD PUMP


Drilling rig• The hole is a “mining object” that has minor diameter compared to the length.

•It serves as the conduit for hydrocarbons from the layer to the surface.

•Drilling of the hole is accomplished by:- connecting the bit and drill string,- adding the pipes as the bit progresses,- work of bit or crown at the bottom of the hole (drilling), along

with circulating mud to take out drilled particles- withdrawing the drill string (e.g. to change worn bit).


1. Bit2. Sub: bit – drill collar3. Drill collars4. Drill pipes5. Sub: drill pipe - kelly6. Kelly7. Preventer stuck8. Rotary hose9. Swivel10. Rotary table11. Draw work12. Power engines and transmission13. Mud pumps14. Mud tanks15. Hook and traveling block16. Mast/derrick17. Wire rope/drilling line18. Crown block


• Drilling rig schematics through three aspects of energy transmission

a – sub; drill collar - bitb – sub; kelly – drill pipec – sub; swivel - kellyd – hooke – wire ropef – mechanical transmissiong – mud discharge linesh – mechanical transmissioni – mechanical transmissionj – drive bushing


Drilling rig• To drill the hole it is necessary to:

- rotate the bit or crown,- put weight on bit,- remove drilled formation from the bottom of the

hole, to enable bit contact with clean surface of intact formation.

• Drilling is unique mechanical and hydraulically process that defines drilling rig construction and energy transmission.


Bit rotation• There are three ways to rotate the bit:

- with rotary table,- top drive and - down hole motor.

•When rotation is generated from the surface, all drill pipes and drill collars with the bit are rotated:

• by the use of rotary table (needs kelly),• or by top drive (no kelly).


Weight on the bit

• To penetrate with destructing elements of the bit, certain amount of the weight must be obtained on the bit.

•The weight is achieved by the use of the weight of the part of drill collar, and the rest of the weight of the bit, drill pipes,kelly, swivel, traveling block and hook are suspended on the drill line and the draw work through friction effect of the brake.


Removing parts of drilled formation from the bottom of the hole

• When bit rotates and is weighted with certain axial force his teeth or inserts crush or cut the rock. •Formation cuttings have to be removed from the bottom hole immediately. •That enables bit contact with intact rock and prevents pipe stacking. •That is the third component that completes the term drilling in basic sense.


Drilling rig• According to mobility drilling rigs can be:

- light, mobile, often set on adequate vehicle and

- heavy plants, that are driven on the location in parts and there assembled.

• Main defining parameters of the drilling rig are:- rated derrick load (hook load),- rig power, ability to rise and lower certain amount of drilling equipment and the hook average speed,- pumping volume and the working mud pump pressure,- rotary table rotation speed or indirectly bit rotation speed, - derrick dimensions and substructure dimensions and ratings.


Derrick (mast)•Derrick is trussed steel construction, that serves as a carrying structure while drilling.

• Sheave blocks suspended on the drilling line in such structure, carry drill stem during drilling process or maneuver.

•A standard derrick is a structure with four supporting legs situated on the picks of the square supporting base.


Derrick (mast)

•There are two different ways of installing the derrick on the working place (location):

- first is to assembly the derrick of the segments in stand up position,

- second is to assembly the segments when laying on the ground and that erect the mast by the use of own draw work and transmission.


• Often the mast or derrick is erected on a substructure, which serves two main purposes:

(1) supports the rig floro, and provides the working space for equipment and workers,

(2) provides the space under the floor for well head and blowout preventers.


• Substructure supports full derrick load, rotary table load, and the load of the drill stem that can be suspended in the hole by the slips, on the hook, or rests i finger.

•When lowering casing in the hole special spider serves toaccommodate pipes of large diameter. • Working floor also accommodates draw work, rotary table, control panels and auxiliary equipment.


Derrick (mast)• Derrick height does not influence of his loading rating, but influences on the length of drill string that can be manipulated as a section.

•Such length is defined by the “working height” of the derrick, that defines the distance of hook traveling from the lowest to the highest point inside the derrick.


Derrick (mast)

• As the standard enabled is the use three pipes connected in the stand with threaded connections.

•For average stand length of 27 meters, standard derrick height is about 41 meter.


Derrick characteristics are defined in API spec.4F Derrick (mast)

Basic derrick dimensions

Tolerances:

AT ±0,1524 m; BT ±0,127 m; CT +1,0668 m; DT ±0,0508 m; ET ±0,1524 m

HE

IGH

T

BA

SE

WID

TH

OP

PE

NIN

G H

EIG

HT

(DR

AW

WO

RK

SID

E)

OP

PE

NIN

G H

EIG

HT

(FR

ON

T S

IDE

)

CR

OW

N W

IDTH

STA

ND

PIP

E H

EIG

HT

AT BT CT CT DT ET

m m m m m m10 24,38 6,10 2,29 7,21 1,68 2,4411 26,52 6,10 2,29 7,21 1,68 2,4412 28,65 7,32 2,29 7,21 1,68 2,4416 37,19 7,32 2,29 7,21 1,68 2,4418 41,45 7,92 2,29 7,21 1,68 3,66

18A 41,45 9,14 2,29 7,21 1,68 3,6619 42,67 9,14 2,29 8,08 2,29 5,1820 44,81 9,14 2,29 8,08 1,97 5,1825 56,61 11,28 2,29 8,08 2,29 5,18

MA

RK


Derrick load-bearing capacity

• The derrick must carry full load of drill stem while drilling orwhen suspended in rotary, or set up in finger. That results withstresses and strains. Additional load is generated when derrick with pipes in finger is exposed to strong wind or vibrations of any kind or reason. Because of that the derrick must be designed to withstand loads of doubled amount compared with those calculated for the job:Derrick load-bearing capacity is that amount of weight that can be suspended in the derrick with adequate safety factor if additional preconditions are fulfilled:

- all four legs are equally weighted- there are no pipes in the derrick and no additional load due high

wind- the weight of the derrick is neglected.


Derrick load-bearingcapacity

•Maximal static hook load of conventional derrick is such load that can be carried by the derrick and the hook with safety factor (about 2). In that case the derrick weight, crown and traveling block weight, wire rope weight and similar must be included. Maximal hook load is:

Qk – maximal static hook load, Nk – number of sheaves in traveling

block,Qt – allowed derrick load

(manufacturer data), N

tk Qk

kQ ++⋅⋅

=42

2


Derrick erection


Power transmission• Two common means of

power transmission are: mechanical and electrical. • In the past most rigs were mechanical. • Analyzing efficacy of energy transmission on drill rigs greater effect is in use of diesel-electric rigs.• Mechanical transmission uses clutches, couplings, belts, gears, sprockets, chains, shafts, bearings and pulleys to transfer the power.


Power transmission

• On a diesel-electric rig, diesel engines, which on land rigs are located at ground level, away from the rig floor, drive electric generators.

• Produced electricity is sent through cables to electric switch and control station.

• Thereof, through additional cables electricity goes to electric motors that are attached directly to the drive shaft of the user; mud pumps, draw work, rotary table .

• Main advantage of such energy transmission is in avoiding complicated mechanical compound, that needs precise aligning.


Systems of energy transmission on rotary

drilling rig

(a) mechanical

(b) diesel-electric


Pipe manipulation system – Hoisting system

•Draw work is a huge piece of machinery that consists of a drum with spooled wire rope, additional drum called cathead spool with catheads on either end.

• To facilitate speed and direction change, several other shafts, clutches, chain-and-gear drives are used.


Pipe manipulation system – Hoisting system

•Two main purposes of the drawworks are:

• to lift pipes out of the hole, and• to lower the pipes back in the hole.

•Work of hoisting system is done by spooling (wrapping) wire rope on the drum.

•When lowering, the gravitation is used to initiate pipe movement.


Pipe manipulation system – Hoistingsystem

•Connected to the hoist are additional system that allow driller to control the weight on the bit while drilling, and with good accuracy the amount of drill pipes or casing that is suspended on the hook – the brakes.

•System comprises at last two kinds of brakes:

•friction brake (main brake)

•and hydraulic or electric brake (auxiliary brakes).


Drawworks

• The way of transforming or energy transport is achieved by - transmission system.

• System allows driller to change drum rotation speed in two, four, six or more (complicated) values.

• Optimal system has minimal two speeds, optimal four, and maximal eight speeds.


Drawworks - Catheads

• Another feature of the drawworks is achieved through cat shafts and catheads.

•The makeup or spinning, cathead on driller’s side is used to spin and tighten drill pipe joints.

•The other on opposite side –breakout cathead is used to loosen the drill pipe when pulled from the hole


Drawworks - Catheads

•Hemp rope or chain are used to connect catheads with pipes.

•Cathead can also be used to manipulate with light weights (e.g. one drill pipe from the storage to the rig floor).

•For such purposes air hoists are used mostly.


Blocks• The traveling block, crown block, and drilling line are the three components are essential in pipe manipulation.

• Their function is to support the load of pipe in the derrick or mast as it is lowered into or withdrawn from the hole.

• During drilling operations, this load consists of the hook, swivel, kelly, drill pipe, drill collars, and a bit attached to the bottom of the drill collars.

• During cementing operations, a string of special pipe called casing, often a heavier load than the drill pipe and collars, has to be lowered into the hole and cemented. DRUM

BRAKE

FASTLINE

CROWN BLOCK

DEADLINE

TRAVELING BLOCK

WIRE ROPE

α


Blocks and drilling line

• Three main parts of the system are:

•traveling block•crown block, and•drilling line

• The purpose of the system is to accept all pipe loads suspended on hook and transfer them to the drawworks.


Drilling line – wire rope

• Wire rope is produced of same or different diameter of steel wires.

•The inner core i produced of hemp fiber core

• Rope diameter is from 28,58 mm (1 1/8”) to 38,1 mm (1 1/2”).

• Proper use of the wire rope implies lubrication.

• Bending and dynamic loading of the rope when combined with blocks cause the wear of the rope so it has to be moved periodically (slipped or cutoff).


Drilling line – wire rope

• One end of the rope is suspended in the brake crest.

•The other end is fixed in the dead line anchor


Blocks

• Large pulleys or sheaves mounted on a framework through which the drilling line is fitted are up to 1,32 m (52”) in diameter, and their axes up to 0,3048 m (1ft).

•Number of sheaves in traveling block is always for one sheave les than in crown block (dead line sheave).


Blocks

•The hook is suspended on the traveling block.

-Hook can be an integral part of the traveling block or can be hung on the bail. -Bail is also used to hung up the swivel on the hook. -On both sides of the hook are two additional bails that bear elevator, that serves in pipe manipulation.


The rotating equipment

• The rotating equipment from top to bottom consists of the:1. swivel, 2. the kelly, 3. the rotary table, 4. the drill stem and 5. the bit.


The rotating equipment

• The drill stem is the assembly of equipment between the swivel and the bit; including the:- kelly, - drill pipe, and - drill collars.

• The term drill string simply refers to the drill pipe and drill collars; however, in the oil patch drill string is often used to mean the whole works.


Swivel

• A swivel is a remarkable mechanical device.

• It is attached to the traveling block by a large bail.

• The swivel has three main functions:

1. it supports the weight of the drill stem;

2. it allows the drill stem to rotate; and

3. it provides a pressure-tight seal and passageway for the drilling mud to be pumped down the inside of the drill stem.


Swivel

• The drilling fluid is under extreme pressure -sometimes exceeding 21 MPa(3,000 pounds per square inch (psi)).

• The fluid comes in through the gooseneck, a curved pipe that connects the swivel to a hose carrying the drilling fluid from the mud pump.

• The fluid then passes through the washpipe, a vertical tube in the center of the swivel body, and into the kelly and drill string.


Kelly and Rotary Table• The kelly is a three-, four-, or

six-sided length of pipe, about 12,19 m (40 feet) long, that is the upper part of the drill stem. – It serves as a passageway for the

drilling fluid on its way into the hole and transmits the rotary movement to the drill pipe and bit.


Kelly and Rotary Table• The kelly's upper end is

connected to the swivel, and its lower end is connected to the drill pipe.

• The drill pipe screws onto a device called a kelly saver sub, or a saver sub.

• The sub is a short, connecting fitting that screws onto the bottom of the kelly.


Kelly and Rotary Table• The kelly fits into a

corresponding square or hexagonal opening in a device called a kelly, or drive, bushing.– The kelly bushing fits into a

part of the rotary table called the master, or rotary, bushng.

– As the master bushing rotates, the kelly rotates; and as the kelly rotates, the drill string and bit rotate.


Kelly and Rotary Table• The bottom threads on

the sub are temporarily joined with threads on the top of each length of drill pipe that is added to the stem.

• The sub saves wear on the threads of the kelly; when the threads of the sub become worn, the sub is replaced or rethreaded.


Upper kelly cock• An upper kelly cock is a special

valve that can often be recognized as a bulge on the upper part of the kelly. – The kelly cock can be closed to

shut off well pressure coming up from inside the drill stem.

– Most kelly cocks require a special wrench to operate the closing valve, and the driller should make sure that the kelly cock wrench is kept in one place and that every crew member knows where to find it.


Lower kelly cock• A lower kelly cock (also called a drill

pipe safety valve or a drill stem valve) is usually made up between the lower end of the kelly and the top joint of drill pipe. – When the kelly is pulled up high above

the rotary table, as it usually is when a joint of pipe is being added to the drill stem (i.e., when a connection is being made), the upper kelly cock cannot be reached easily should it be necessary to close in the drill stem.

– However, the lower kelly cock is readily accessible when the kelly is raised.


Rotary table

• Rotary drilling derives its name from the rotary table. – The rotary table is powered by the

compound or by its own electric motor.

– The rotary table also accommodates the slips - a tapered device lined with strong, teeth like gripping elements that hold the pipe suspended in the hole when the kelly is disconnected.


Rotary table

– The rotary table also accommodates the slips - a tapered device lined with strong, teeth like gripping elements that hold the pipe suspended in the hole when the kelly is disconnected.


Drill String• The drill string is made up of the drill pipe and special, heavy-walled pipe called drill collars. – Each length of drill pipe is

about 9,14 m (30 feet) long and is called a joint of pipe.

– Each end of each joint is threaded.

– The end of the joint with the interior threads is known as the box, and the end of the joint with the exterior threads is called a pin.


Drill String

– When pipe is made up (joined together), the pin is stabbed into the box and the connection is tightened.

– The threaded ends of the pipe are called tool joints and are actually separate parts that are welded onto the outside of the drill pipe body by the manufacturer who cuts the threads to industry specifications.


Drill String

• Drill collars, like drill pipe, are steel tubes through which mud can be pumped. – Drill collars are heavier than drill pipe and

are used on the bottom part of the string to put weight on the bit.

– This weight presses down on the bit to get it to drill.

– Drill collars are about 9,14 m (30 feet) long and, unlike the drill pipe that has tool joints welded on, they have the boxes and pins cut into them.

a) b) C)

a) standard

b) square

c) spiraled


Bits

• Two main types of bits have been developed through the years for more efficient drilling. – Roller cone, or rock bits have cone-shaped

steel devices called cones that are free to turn as the bit rotates.

– Most bits have three cones, although some have two and some have four.

– Bit manufacturers either cut teeth out of the cones or insert very hard tungsten carbide buttons into the cones.


Bits

• The teeth are responsible for actually cutting or gouging out the formation as the bit is rotated. – All bits have passages drilled

through them to permit drilling fluid to exit.

– Most bits have nozzles that direct a high-velocity stream or jet of drilling fluid to the sides and bottom of each cone so that rock cuttings are swept out of the way as the bit drills.


Diamond bits

• Diamond bits do not have cones, nor do they have teeth. – Instead, several diamonds

are embedded into the bottom and sides of the bit.

– Since diamonds are so hard, diamond bits are especially suited for drilling hard rock formations but can also be used effectively on soft formations.


Polycrystalline diamond bits

• PDC bit cutting elements have polycrystalline diamond cutter with transitional layer for strike absorption.

• They are embedded in bit body and some manufacturers make them interchangeable.

• Are produced with steel bodies or with impregnated matrix.

• PDC bits have interchangeable jet nozzles made of tungsten carbide.


Circulating System

• One of the essentials of rotary drilling is a circulating system. – For the rotary drilling system to

function, fluid must be circulated downward through the drill stem, around the bit, and upward in the annular space between the drill stem and the wall of the hole or the casing. borehole.


Circulating System

• The principal purposes of circulation fluid are to:

1. clean the bottom of the hole;2. cool the bit;3. flush cuttings from the hole;4. support the walls of the well so that they do

not cave in; and5. prevent the entry of formation fluid into the

borehole.


Drilling Fluid

• The circulation fluid is usually a liquid but can also be air or gas. (Remember, a fluid can be either a liquid or gas.)

– If the circulating, or drilling, fluid is a liquid, it is made up mostly of water, although occasionally oil is the major component.

– Both types of drilling fluids are called muds, or drilling muds, because that is what they appear to be.


Drilling Fluid

• Nevertheless, some drilling muds are quite a bit more than just muds; literally scores of special chemical additives and weighting materials are put into them in order to achieve their purpose with the greatest efficiency.

– Special clays are used to give body to the mud, and barite -a heavy mineral- is added to increase the density of the mud.

– Chemicals are used to control the thickness, or viscosity, of the mud and to improve the ability of the solid particles in the mud to deposit a layer, or cake, on the wall of the hole.


Drilling Fluid

• In perhaps 1 percent of all oilwells drilled, compressed air or natural gas is used as the circulating fluid instead of mud.

– Conditions are usually such that air drilling, although a very efficient drilling method, cannot be used.

– Circulating with a liquid is less efficient but offers the advantages of hydraulic lift (such as its ability to lift cuttings made by the bit), pressure buildup as depth increases, and so on.


Mud Tanks and Pumps • The mud is mixed in the

mud tanks (often called mud pits) with the help of a mud hopper into which most of the dry ingredients for the mud are poured. (It is very important to note that some dry ingredients, especially one called caustic, should never be added to the mud through the hopper.


Mud Tanks and Pumps • The hopper works in such a

way that it often throws out a little of the ingredients being added to it. Since caustic is just that -caustic- one can easily receive a severe burn from such ejected particles.)

– The tanks contain agitators(paddle like projections) and jets that mix the mud.

– The mud is mixed with either oil or water, depending on the mud properties needed.


Mud Pumps • The mud pump is the

primary component of any fluid-circulating system.

– Pumps are either powered by electric motors attached directly to them, or driven by the compound.

– The pumps for rotary drilling rigs have high ratings and are capable of moving large volumes of fluid at very high pressures.

– When circulating with air or gas, the pump is replaced by compressors, and mud tanks are not required.


The Mud Cycle

• The mud is pumped from the mud suction tankthrough a discharge line to a standpipe. – The standpipe is a steel pipe

mounted vertically on one leg of the mast or derrick.

– The mud is pumped up the standpipe and into a flexible, very strong, reinforced rubber hose called the rotary hose, or kelly hose.


The Mud Cycle

• The rotary hose is connected to the swivel. – The mud enters the swivel,

flows down through the kelly, drill pipe and drill collars, and exits at the bit.

– It then does a sharp U-turn and heads back up the hole through the annulus, a space between the outside of the drill string and wall of the hole.


The Mud Cycle

• Finally, the mud leaves the hole through a steel pipe or trough, called the mud return line, and falls over a vibrating, screen like device called the shale shaker. – The shaker screens out the

cuttings and dumps them into a reserve pit.

– The mud then drains back into the mud tanks and is recycled back down the hole by the mud pump.


• If fine silt or sand is being drilled, devices called desilters and desanders are mounted on the mud pits to remove these very small particles. – Recirculating silt and sand

back down the hole makes the mud heavier than desired and might erode the drill string and other components.


Mud-Gas Separator

• A mud-gas separator is an essential item of rig equipment for handling a gas kick. – The mud-gas separator

saves the usable mud coming out of the well while a kick is being circulated out and separates the flammable gas so it can be burned at a safe distance from the rig.


Mud-Gas Separator

• Most mud-gas separators are made of a length of large-diameter pipe. – Interior baffles are used to slow down the mud-gas

stream, and a gooseneck arrangement at the bottom permits the mud to flow to the shaker tank while maintaining a fluid head to hold the gas at the top.

– The gas vent pipe at the top permits the gas to be flared without too much back-pressure on the mud.


• And, if a formation containing small amounts of gas is encountered, a degasser is often employed to remove the gas from the mud before it is recirculated into the hole. – Mud containing gas (gas-cut mud) should not be

recirculated because it decreases the density of the mud, which could lead to a blowout.


Well Control Equipment• When the subject of well

control is mentioned, the first thing to come to mind is a blowout. – A blowout is a very

undesirable occurrence on any rig, because it endangers the lives of the crew, can destroy a rig worth millions of dollars, wastes much-needed petroleum, and may damage the environment.

– Although relatively rare, a blowout is an awesome sight.


Well Control Equipment

• Fluid (either liquid or gas) erupts from the well, usually with great force, and often ignites into a roaring inferno, especially if the fluid is gas. – The trouble arises when the

pressure in the formation is higher than that in the well.

– The pressure in the well is maintained by the type and amount of drilling fluid being circulated through it.


Well Control Equipment

• Ordinarily, the drilling mud prevents the formation fluid from getting into the borehole and blowing out, but under certain conditions fluid sometimes enters the hole and causes difficulties. – The well kicks-that is, formation fluid enters the hole,

and some of the drilling mud is forced from the hole. – If the crew does not take prompt and proper action at

the first indications of a kick, then eventually all of the mud could be spewed out of the hole, allowing the formation fluid to flow uncontrolled to the surface.

– The result is a blowout.


Blowout Preventers• Blowout preventers (BOPs),

in conjunction with other equipment and techniques, are used to close the well in and allow the crew to control a kick before it becomes a blowout. – The two basic types of

blowout preventers on a drilling rig are annular preventers and ram preventers.


Blowout Preventers

• An annular preventer has a rubber sealing elementthat, when activated, closes tightly around the kelly, drill pipe, or drill collars; or, if no part of the drill stem is in the hole, it closes on the open hole.


Blowout Preventers• Ram preventers consist of

large, steel valves (the rams) that have sealing elements. – One type of ram preventer is

called a pipe ram because it closes on the drill pipe and is not able to affect a seal on an open hole.

– Blind-ram preventers are used to close an open hole.

– Shear rams, used mostly in offshore drilling, cut the drill pipe completely, thus sealing the hole.


Blowout Preventers

• Usually several blowout preventers are installed on top of the well in a stack with the annular preventer at the top and the pipe rams and blind rams below. – Several preventers are

installed together in this way so that an impending blowout, or kick, can be controlled even if one or more of the preventers fail.


Accumulator“Koomey”

• Blowout preventers are opened and closed by hydraulic fluid, which is stored under pressure in a device called an accumulator – Several bottle-shaped or ball-

shaped containers are located on the operating unit, and hydraulic fluid is stored in these containers.


Accumulator“Koomey”

• The accumulator is usually located at least 30,48 m (100 feet) away from the rig floor so that, if a blowout and fire occur, the accumulator is not damaged and valves on the accumulator can be used to close the preventers.

– A master control panel located on the rig floor is normally used to operate the preventers.


Choke Manifold

• When a kick is incurred, closing in the well with one or more of the blowout preventers is only the first step that must be taken. – In order to resume drilling, the kick must be

circulated out, and mud of the proper weight must be circulated in (i.e., the well must be killed, or brought under control).

– Therefore, a series of valves called the choke manifold is installed as part of the system.


Choke Manifold

• The choke manifold is connected to the blowout preventer stack with a choke line. – When the well is

closed in with the blowout preventers, the mud and intruded formation fluid are circulated out the choke line and through the choke manifold.


• A choke is simply a valve. – There are adjustable

chokes and fixed chokes.

– An adjustable choke is operated pneumatically or hydraulically and has an opening that is capable of being restricted or pinched in; it may be infinitely variable in size between full open and closed.

Choke


Choke– A fixed choke has a flow restriction of permanent size.

– In either case, the idea is that the well can be circulated "through the choke" and adequate back-pressure held on the well to prevent the further entry of formation fluids while well-killing procedures are being carried out.


Auxiliaries

• In addition to the major assemblies of equipment that make up a drilling rig, a great number of minor pieces of equipment are necessary to carry on the work. – Some of these auxiliaries are:

• generators, • air compressors, • mud storage facilities, and • various instruments.


Electricity Generators

• Modern rotary rigs are provided with alternating-current generators, nearly always diesel powered. – Most of these generators have capacities of 50 to 100

kilowatts, although larger units are sometimes installed. – They have enough capacity to carry the main power load

of the rig-excluding hoisting, pumping, and rotating-using only one unit.

– Alternating-current electricity is used for rig lighting, shale shaker motors, mud pit agitators, centrifugal pumps, rig instruments, engine-cooling fans, and air conditioning for the bunkhouses furnished on many large rigs.


Air Compressors

• On mechanical rigs, a small compressor is usually mounted on the engine compound to supply air for the pneumatic controls and clutches. – The compressor has a volume tank to allow reserve

storage of compressed air. – Diesel-electric rigs usually have an electrically powered

compressor to furnish high-pressure air to pneumatic controls and for other purposes, including starting the main engines and operating the air-powered hoists, air slips, air pumps on the BOP-operating equipment, water wells, air-operated tools, and the like.


Mud Storage Facility

• A complete mud system for a heavy-duty drilling rig usually includes not only settling tanks, or pits, but suction tanks, or pits, to which the pump is connected. – It also frequently includes a reserve or waste pit

where surplus mud and cuttings are accumulated as drilling progresses.

– Some form of storage for the dry and liquid mud materials that are to be added as the drilling progresses is found on most rigs.


Mud Storage Facility

• Dry mud storage bins, an oil tank, and centrifugal pumps for mud mixing are necessary for the circulating system. – If a rig is in a remote location, adequate storage

for the dry components of the drilling mud is especially desirable so that the mud may be treated readily without waiting for a mud company to deliver a supply from its warehouse.

– Sacked mud materials and chemicals are usually stored under cover for protection from severe weather.


Drilling Instruments

• An instrumentation system is a key part of almost all rigs today. – It may be no more than one simple

weight indicator, or it may include a great variety of things such as a mud level recorder, a mud density recorder, torque indicators and recorders, and logging devices to keep a continuous graphic record of work being done on the rig, particularly the depth being drilled.


Drilling Instruments

• Figure shows the instruments placed at the driller's position for observing drill stem weight, mud pit level, pump pressure, rotary speed, tong-line pull, and other variables. – A mud logging unit, generally

supplied by a contracting service company, may be used to keep track of any indications of oil and gas brought up in the circulating fluid.


Other Facilities • Drilling rigs also generally include such facilities as fuel

storage installations; a change house (a place for rig workers to change from their work clothes to street clothes); a doghouse (a small structure on the rig floor that serves as an office for the driller and as a storage place for small tools); a tool house (a place to store spare parts for the pumps and other equipment); and other facilities. Rigs located in remote areas frequently have a bunkhouse where the rig crews live while on duty. – Sometimes, the tool pusher is provided with a trailer that serves as an

office with a telephone and radio for communication with the head office and as his living quarters while on duty.


Other Facilities • Offshore rigs are provided with sleeping quarters,

mess facilities, electric power, water supply, and sewage facilities, as well as storage for enough dry mud, chemicals, cement, oil, and other supplies to operate the rig for many days. – Most large rigs are equipped to continuously transmit

operation data by radio to the company headquarters.– Good rig housekeeping requires that there be a place for

everything while drilling is underway. – Pipe racks and casing racks are standard items used for

temporary storage. – Provisions are made for moving and storing hand tools used

in rig maintenance.


The Crew • Although not a component of the rig as

such, the crew is a very important part of the rig. Without the individuals in the crew, the equipment for rotary drilling would be worthless.

• Crews may consist of four, five, six, or more individuals, depending on the size and service rating of the rig itself.


The Crew • The tool pusher also called rig manager – is

the man in charge.– His experience includes years of work on a drilling

rig as a crewman and driller;– He has expert knowledge of well drilling, rig

machinery, tools and equipment. – He directs the actual operation of the drilling rig

and the work performed by the drilling crew, authorizes the employment of the crew and coordinates the affairs of the operating company and drilling contractor.


The Crew • The driller is in charge of

drilling; he operates the drilling machinery.– He is under the direct

supervision of the tool pusher and is the overall supervisor of the floor men.

– The driller gives the actual instructions concerning work on the rig to the other five or six crew members.


The Crew • The derrick man works on the

monkey board, a small platform located up in the derrick at a level even with the upper end of a stand of drill pipe.– When the pipe is being tripped in

or out, he handles the upper end of the pipe, guiding it to and from the finger.

– When drilling is going on he is responsible for maintaining the drilling fluid or repairing the pumps and other circulating equipment.


The Crew

• The motorman is responsible for the engines, fuel, and auxiliaries.

• Electrician maintains and repairs the electrical generating and distribution system on the rig.

• The floor man; rotary helper or roughneck, is responsible for handling the lower end of the drill pipe when it is being tripped in or out of the hole, handle the tongs, maintain equipment, keep it clean and painted, and keep the rig in general repair.

Date post:	04-Apr-2018
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