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A STUDY OF DIFFERENT DRILLING EQUIPMENTS AND MACHINES AND THEIR MAINTENANCE INDUSTRIAL TRAINING AT OIL AND NATURAL GAS CORPORATION LIMITED (CACHAR FORWARD BASE) BY ABHISHEK PAUL CHOUDHURY (REG. NO. 200915002) A TRAINING REPORT SUBMITTED FOR THE PARTIAL FULFILLMENT OF THE REQUIREMENT FOR BACHELOR OF TECHNOLOGY OF MECHANICAL ENGINEERING ACADEMIC SESSION (2009-2013) 1

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Page 1: ONGC Project1

A STUDY OF DIFFERENT DRILLING

EQUIPMENTS AND MACHINES AND THEIR

MAINTENANCE

INDUSTRIAL TRAINING AT OIL AND NATURAL GAS CORPORATION LIMITED (CACHAR FORWARD BASE)

BY

ABHISHEK PAUL CHOUDHURY

(REG. NO. 200915002)

A TRAINING REPORT SUBMITTED FOR THE PARTIAL FULFILLMENT OF THE REQUIREMENT FOR

BACHELOR OF TECHNOLOGY OF MECHANICAL ENGINEERING

ACADEMIC SESSION (2009-2013)

OF

SIKKIM MANIPAL INSTITUTE OF TECHNOLOGY, MAJITAR

OF

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SIKKIM MANIPAL UNIVERSITY OF HEALTH, MEDICAL AND TECHNOLOGICAL SCIENCES, GANGTOK

STUDENT’S DECLARATION

I HEREBY DECLARE THAT THE INDUSTRIAL TRAINING REPORT ENTITLED

“A STUDY OF DIFFERENT DRILLING EQUIPMENTS AND MACHINES AND

THEIR MAINTENANCE”SUBMITTED IN PARTIAL FULFILLMENT OF THE REQUIREMENTS FOR THE DEGREE OF

BACHELOR OF TECHNOLOGY OF MECHANICAL ENGINEERING

TO

SIKKIM MANIPAL INSTITUTE OF TECHNOLOGY, MAJITAR

ABHISHEK PAUL CHOUDHURY

REG. NO. 200915002

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EXAMINER’S CERTIFICATION

THE INDUSTRIAL TRAINING REPORT OF

ABHISHEK PAUL CHOUDHURY

REG. NO. 200915002

TITLE

“A STUDY OF DIFFERENT DRILLING EQUIPMENTS AND MACHINES AND

THEIR MAINTENANCE”

IS APPROVED AND IS ACCEPTABLE IN QUALITY AND FORM

Internal Examiner: External Examiner:

Dr. B.B. Pradhan

HOD

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Mechanical Engineering

Sikkim Manipal Institute Of Technology

ABOUT O.N.G.C.

Oil and Natural Gas Corporation Limited (ONGC) (NSE: ONGC, BSE: 500312) is an Indian state-owned oil and gas company headquartered in New Delhi, India. It is one of the largest Asia-based oil and gas exploration and production companies, and produces around 77% of India's total crude oil production (and around 30% of total demand) and around 81% of natural gas production. It is one of the largest publicly traded companies by market capitalization in India and the largest India-based company measured by profits.

ONGC was founded on 14 August 1956 by the Indian state, which currently holds a 74.14% equity stake. It is involved in exploring for and exploiting hydrocarbons in 26 sedimentary basins of India, and owns and operates over 11,000 kilometers of pipelines in the country. In 2010, it was ranked 18th in the Platts Top 250 Global Energy Company Rankings and 413th in the Fortune Global 500.

History

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Foundation to 1961

During the pre-independence period, the Assam Oil Company in the northeastern and Attock Oil company in northwestern part of the undivided India were the only oil companies producing oil in the country, with minimal exploration input. The major part of Indian sedimentary basins was deemed to be unfit for development of oil and gas resources.

After independence, the national Government realized the importance oil and gas for rapid industrial development and its strategic role in defense. Consequently, while framing the Industrial Policy Statement of 1948, the development of petroleum industry in the country was considered to be of utmost necessity.

Until 1955, private oil companies mainly carried out exploration of hydrocarbon resources of India. In Assam, the Assam Oil Company was producing oil at Digboi (discovered in 1889) and Oil India Ltd. (a 50% joint venture between Government of India and Burmah Oil Company) was engaged in developing two newly discovered large fields Naharkatiya and Moran in Assam. In West Bengal, the Indo-Stanvac Petroleum project (a joint venture between Government of India and Standard Vacuum Oil Company of USA) was engaged in exploration work. The vast sedimentary tract in other parts of India and adjoining offshore remained largely unexplored.

In 1955, Government of India decided to develop the oil and natural gas resources in the various regions of the country as part of the Public Sector development. With this objective, an Oil and Natural Gas Directorate was set up towards the end of 1955, as a subordinate office under the then Ministry of Natural Resources and Scientific Research. The department was constituted with a nucleus of geoscientists from the Geological survey of India.

A delegation under the leadership of Mr. K D Malviya, the then Minister of Natural Resources, visited several European countries to study the status of oil industry in those countries and to facilitate the training of Indian professionals for exploring potential oil and gas reserves. Foreign experts from USA, West Germany, Romania and erstwhile U.S.S.R visited India and helped the government with their expertise. Finally, the visiting Soviet experts drew up a detailed plan for

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geological and geophysical surveys and drilling operations to be carried out in the 2nd Five Year Plan (1956-57 to 1960-61).

In April 1956, the Government of India adopted the Industrial Policy Resolution, which placed mineral oil industry among the schedule 'A' industries, the future development of which was to be the sole and exclusive responsibility of the state.

Soon, after the formation of the Oil and Natural Gas Directorate, it became apparent that it would not be possible for the Directorate with its limited financial and administrative powers as subordinate office of the Government, to function efficiently. So in August, 1956, the Directorate was raised to the status of a commission with enhanced powers, although it continued to be under the government. In October 1959, the Commission was converted into a statutory body by an act of the Indian Parliament, which enhanced powers of the commission further. The main functions of the Oil and Natural Gas Commission subject to the provisions of the Act, were "to plan, promote, organize and implement programmes for development of Petroleum Resources and the production and sale of petroleum and petroleum products produced by it, and to perform such other functions as the Central Government may, from time to time, assign to it ". The act further outlined the activities and steps to be taken by ONGC in fulfilling its mandate.

1961 to 2000

Since its inception, ONGC has been instrumental in transforming the country's limited upstream sector into a large viable playing field, with its activities spread throughout India and significantly in overseas territories. In the inland areas, ONGC not only found new resources in Assam but also established new oil province in Cambay basin (Gujarat), while adding new petroliferous areas in the Assam-Arakan Fold Belt and East coast basins (both inland and offshore). ONGC went offshore in early 70's and discovered a giant oil field in the form of Bombay High, now known as Mumbai High. This discovery, along with subsequent discoveries of huge oil and gas fields in Western offshore changed the oil scenario of the country. Subsequently, over 5 billion tonnes of hydrocarbons, which were present in the country, were discovered. The most important contribution of

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ONGC, however, is its self-reliance and development of core competence in E&P activities at a globally competitive level.

A turning point in the history of India’s oil sector was in 1994. While the oil sector was on the backburner of India's political realm for some time, it was brought to the forefront by the privatization of India's leading oil E&P organization, the ONGC. Simultaneously, there were steps taken for the enhancement of production on the Bombay High oil fields as the result of a INR 150 billion development investment.

One of Asia's largest oil E&P companies, ONGC became a publicly held company as of February 1994, following the Indian government's decision to privatize. Eighty percent of ONGC assets were subsequently owned by the government, the other 20% were sold to the public. At this time, ONGC employed 48,000 people and had reserves and surpluses worth INR 104.34 billion, in addition to its intangible assets. The corporation's net worth of INR 107.77 billion was the largest of any Indian company.

After its initial privatization, ONGC had authorized capital of INR 150 billion: it also met its need to raise INR 35 billion to invest in viable oil and gas projects. The Asian Development Bank (ADB) had also set a deadline for privatizing and restructuring at 30 June 1994, if loans were to be granted for development of two ONGC projects. As a consequence of the successful privatization, the loans were granted - US$267 million for development of Gandhar Field, and US$300 million for the gas flaring reduction project in the Bombay Basin. The successfully formulated and implemented privatization strategy put ONGC at par with other large multinational and domestic oil companies.

2000 to present

In 2006 a commemorative Coin set was issued to mark the 50th anniversary of the founding of ONGC, making it only the second Indian company (alongside State Bank of India) to have such a coin issued in its honour.

In 2011, ONGC applied to purchase of 2000 acres of land at Dahanu to process offshore gas.

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ONGC Videsh

ONGC Videsh Limited (OVL) is the international arm of ONGC. It was rechristened on 15 June 1989. It currently has 14 oil and projects across 15 countries. Its oil and gas production reached 8.87 MMT of O+oEG in 2010, up from 0.252 MMT of O+OEG in 2002/03.

International rankings

ONGC has been ranked at 198 by the Forbes Magazine in their Forbes Global 2000 list for the year 2007.

ONGC has featured in the 2008 list of Fortune Global 500 companies at position 335, a climb of 34 positions from rank of 369 in 2007.

Economic Times 500, Business Today 500, Business Baron 500 and Business Week recognize ONGC as most valuable Indian corporate, by Market Capitalization, Net Worth and Net Profits.

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INDEXTOPIC PAGE NUMBER

DRILLING RIG, AN INTRODUCTION 12

POWER PLANT EQUIPMENT 20

HOISTING EQUIPMENT 36

ROTATING EQUIPMENT 50

CIRCULATING FLUID EQUIPMENT 54

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ACKNOWLEDGEMENT

Nothing concrete can be achieved without an optimal combination of inspiration and perspiration. No work can be accomplished without the guidance from the experts. It is only the critics from the engineer intellectuals that help transform a product into a quality product.

At the outset, I extend my sincere and heartiest thanks to the almighty God for providing me good health and spirit.

I am very much grateful to Mr. A. K. Gadiwan, Chief Engineer, Mechanical Engineering, Oil And Natural Gas Corporation Limited, Cachar Forward Base for his continuous and untiring efforts to complete this project in the present form.

I would like to thank the Department of Mechanical Engineering, Sikkim Manipal Institute Of Technology, for their cooperating and helping to make this project a worthy one.

Last but not the least, I owe a debt of gratitude to my parents for their moral help and support.

And there is no end to the road……………

With thanks,ABHISHEK PAUL CHOUDHURY

REG. NO. 200915002

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Rotary drilling rig

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DRILLING RIG, AN INTRODUCTIONINTRODUCTION

Rotary drilling begun in 1900, was expanded and developed through a combination of art and technology. The use of technology in drilling was accelerated during 1970s, although to some degree technology filtered in with the inception of rotary drilling.

In rotator drilling, the disintegration of the rock occurs as a result of a concurrent action of the bit, of a load (pressure) and of a torque. Under the effect of the pressure, the bit penetrates the rock, while under that of the torque it shears it. Cutting from the hole are carried to the surface by drilling mud which is circulated continuously through the drill string. The mud is pumped into the drill pipe at the surface, out of the bit, and up the annular space between the drill pipes and the walls of the hole.

There are two methods of rotary drilling, the rotator method itself, and another means which uses a downhole motor.

The process flow schematic diagram shown in the figure applies to all kinds of rotary drilling.

As is shown in the diagram, drill pipe string 1, terminating into bit 2, is suspended by means of a pulley block. The stationary pulley assembly (crown block 3) is mounted at the top of a derrick or mast 4. The pulley is moving inside the derrick is a travelling block 5. This block is attached to the hook and accommodates the hoisting line via the derrick crown block to provide the means of hoisting or lowering the drill pipe and the casing loads involved in an operation. One end of the hoisting line (the ‘dead’ end) is attached to the derrick base, while its other end (the fast line) is attached to the hoisting drum of draw works 7. The crown block has six or seven sheaves. A sheave block allows the hoisting line load to be reduced. Thus, with a sheave block system pattern of 5X6 involving five sheaves of the travelling block and six sheaves of crown block in use, the hoisting line load is reduced tenfold, and with a weight of , say, 2000KN (the weight of a casing string) conveyed to the pulley block, the load of the line will be only 200KN.

Attached to the travelling block is a hook 8 from which a swivel 9 is suspended. The other end of the swivel is screwed to the top of a Kelly by a left hand thread connection. The swivel supports the drilling string and allows rotation of the pipe without transmitting the torque to the sheave block system. The upper most pipe 10 of the drill pipe string is a Kelly, is a square or hexagonal pipe which is screwed to the top of the drill string by a right-hand thread connection and is itself supported by the swivel. The Kelly passes through the centre opening of the rotary table 11. The opening receives a master bushing with tapered slips forming a square or hexagonal hole to fit the shape of the Kelly.

The rotary table is situated in the centre of the derrick floor immediately over the well bore and directly under the centre of the derrick mast. Its function is to support the weight of any pipe or casing run into or from the hole and to provide rotary motion to the drill pipe string via the Kelly when drilling.

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The table is rotated, the draw works is powered, and other mechanisms driven and actuated from a power plant comprising prime movers 12 (electric motors, diesel engines, gas turbines), a reduction gear, a speed change gear, transmissions, chain, and V-belt drive gears.

The continuous circulation of drilling mud (fluid) is provided by mud pumps 13 and a circulation system comprised of drilling mud flow lines 14 and shale shakers 15. The drilling mud flows by gravity to suction pit 16 along mud return lines having a required fall. Installed in the zone of the circulation system layout are containers and various mechanisms intended for the cleaning, chemical treatment, preparation and weighing the drilling mud.

The drilling process is as follows. The mud pump force the drilling mud from the suction pits into the discharge lines 17. Then, the mud finds its way through standpipe 18, Kelly hose 19 and swivel 9 to the inner channel Kelly 10 and on via the bore of drill pipes 1 to bit 2. Flowing out of the jets in the drill bit, the drilling mud catches rock cuttings produced by the bit and returns back to the surface along the annular space between the borehole wall and drill pipe string. On reaching the earth’s surface the drilling mud flows into the mud return line connected to a casing pipe lowered into the borehole, which is called casing (string) 20. After this, the drilling mud is cleaned of rock cuttings and treated with chemicals, if necessary, to control its properties. The clean and chemically treated mud pumps and forced into the well. The drilling mud flow along the circuit-the suction pit, mud pumps, borehole, circulation system, and suction pit forms the circulation loop.

In order for the rotating bit to break up the rock, a certain force must be applied to press the bit against the rock. This is why the rock bit takes up part of the drill pipe string weight as soon as it touches the bottom of the hole thus building up the necessary axial weight applied on the rock bit. As the borehole is sunk deeper the weight on the bit decreases. In order to maintain the axial weight on the bit at its specified value, the drill pipe string is continuously advanced further down into the well with the aid of the multi-pullies block system and the draw-works.

When the full length of the Kelly enters the borehole, a length of drill pipe must be added to the drilling string. To this end the slush (mud) pumps are stopped. The drilling string is lifted up over the length of the Kelly and suspended by the elevator (or drill pipe slips) carried by the rotator table. The Kelly is then unscrewed into a special shallow hole called the rat hole. As the next step, a single joint of the drill pipe whose length is a bit less than the Kelly length is hoisted inside the derrick by means of the block and tackle system and screwed to the drill pipe string suspended at the rotary table. The drilling string with the drill pipe length added to the top of the drilling string and the mud pumps are restarted. After the drilling mud starts to flow out of the borehole, the rotation of the drill pipe string is started, the rock bit is lowered to the well bottom, and the drilling process is resumed. To replace a worn-out bit, the mud pumps are stopped, the Kelly is unscrewed and lowered into the rat hole, and drill pipe string is pulled out of the well.

During the round trip, the drilling string is broken into sections whose length is dictated by the derrick height. The screwed off sections, called drill pipe stands, are arranged inside the mast in a pipe rack. The top ends of the stands are brought into the finger board located near the racking platform.

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After the whole of the drill pipe string has been pulled out of the borehole, the worn-out bit is replaced, and the drill pipe string is run down the well in reverse order. During the re-running operation a drill pipe stand is attached to the lifted block and tackle system (the travelling block with the hook) by means of a special device, screwed to the drill pipe lowered into the well and supported by the rotary table, and then lowered into the well. After the top end of the pipe stand is fitted on the rotary table with the aid of the elevator, or slips, the travelling block and hook assembly are again lifted to attach a new drill pipe stand, and so on.

Thus, the borehole drilling process comprises the following repeated operations:

1. Running a new rock bit on the drilling string down the well.

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2. Disintegration of the rock with the bit (mechanical drilling).3. Adding new drill pipe length to the string as the borehole is sunk deeper.4. Pulling the drill pipe string out of the well to replace worn-out bits.

The round trip operations are labour consuming. To swing a drill pipe stand away from the well centre and store it in a vertical position, to attach a stand to the travelling block and hook system, to screw and unscrew drill pipe stands requires a great deal of physical work. To reduce the labour consumption and improve working conditions for drilling crews during the round trip operations, powered and automated facilities are used. Large wrenches are powered by air or electrical motors. A pulling-an-running mechanism is used to swing a drill pipe stand off the centre and store it in a specified space on the derrick floor. The pulling-and-running mechanism is used in manual operations for hooking and unhooking drill pipe stands pulled out of the well bringing them in the pipe rack, and holding them in a vertical position. In some regions, automatic pulling-an-running mechanisms are used which preclude manual operations.

When certain depths are reached in borehole sinking, well casing and cementing are performed. To this end, the well is lined with steel pipes and the casing in position is cemented by pumping the cement through the drill pipe to the bottom of the casing and up into the annular space between the casing and the walls of the well bore. After cement sets, the well casing, cement stone, and rock become cemented to each other.

All the above described operations performed during rotary table apply, as well, to downhole motor drilling.

TYPES OF DRILLING RIG

Various types of rotary drilling rigs have been developed to accommodate different onshore and offshore areas which are currently being explored for petroleum. These different types of rigs and their specific uses are described below.

ONSHORE RIGS

Land-based wells are dug with either high floor masts and substructure or with carrier mounted rigs, CARRIER MOUNTED rigs are rigs mounted on mobile, wheeled carriers like IPS CARDWELL-700 rig. They can be driven to the well site all necessary hoisting equipment, engines, and special masts, as complete on-truck units.

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OFFSHORE RIGS

Offshore rigs can be grouped as under:

JACK UPS

A Jack Up rig, (i) provides a fixed platform, (ii) its initial cost is less than others, (iii) it can work soft bottom areas of detail if equipped with mats to support the legs, (iv) it can be designed to withstand hurricane storms, (v) it is best tool available for water depths of less than 300ft.

It has several disadvantages: (i) it is difficult to tow, (ii) legs must be laid down or removed for long moves, (iii) jacking mechanisms have moving parts, (iv) going on or off-location is hazardous, (v) accident underway produced poor safety records.

Jack Ups which employ cans or spud tanks are known as leg type drilling unit. The tanks are fabricated at the lower end of the legs and allow 3500 to 5500 pounds per square foot of bearing load, depending on tank size and weight of drilling unit.

The independent leg drilling unit performs best in firm, uneven bottom such as coral, limestone or boulders. In soft mud where penetration may be 60ft. maximum, the legs sometimes cannot obtain the necessary bearing to support the unit. These units are preloaded, that is, to test the stability .Mat type units, having a much larger area of contact with the sea floor than independent leg units, operate with less bearing pressure from the bottom, usually in range 500 to 600 pounds per square ft. This makes the mat type unit the logical choice for soft mud provided the bottom is more or less level. Mat type units cannot work where the sea floor is erratic or covered with coral heads or boulders that would damage the bottom of the mat. These units are designed to with a bottom slope of 1 degree to 1.5 degree, and

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Offshore rigs Jack UpsFloatersBargesDrillships

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the legs cannot be adjusted for a sloping bottom as the independent leg units can. Mat type units have more drag when under tow than independent leg units. It is having about half the speed of other type.

FLOATERS

These types of floating vessels are in common use these days.

SEMISUBMERSIBLE

The semisubmersible has the primary design advantage of placing the buoyancy chambers below the surface of the water. This minimizes the response to the wave forces, hence stabilizing the motion of the working floor and drill string.

Semisubmersibles are also called “column stabilized units” or “Semis” and have been developed for drilling in choppy seas. Semis show no similarity to a conventional ship.

The deck of a semisubmersible is from 40’s to 70’s above the water surface during drilling. This high deck, when loaded, increases the tendency of the vessel to capsize in rough seas. Also, structural integrity is a severe problem with semis than with shiplike vessels. Initial cost and resulting day rate for

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semis are usually higher than for shiplike vessels. From the above discussion it is evident than semis are designed to operate primarily in deep and rough sea areas.

Advantages: (i) provides a relatively stable drilling platform, (ii) it functions under more severe sea and weather conditions than the others, (iii) its capabilities for water depths are excellent ( upto 1500ft.)

Disadvantages: (i) limited capacity for cargo transportation, (ii) requires more support vessels for supply, anchor handling, etc. (iii) must use marine risers not needed by Jack Ups, (iv) travel speeds are low as compared to drillships.

DRILL SHIPS

The drill ship type has the conventional shipform hull and has the chief advantage of being able to travel from location to location at reasonably good speeds by its own power.

Drill ships have a large number of advantages. Among them are: (i) proven deep water capability, (ii) the capacity to transport much larger loadings of drilling supplies, (iii) faster travel time to remote locations, (iv) no need for tugs, as they are self-propelled, (v) lower operating costs, (vi) adaptable dynamic positioning systems and turret mooring.

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The disadvantage of the drillship appears to be its limited capacity to operate in wind or wave conditions which produce excessive platform motion.

Operating limits for the Offset

Operating – 5 to 6 % of water depth

Suspended – upto 10% of water depth

Disconnected – No limit (Governed by chain or wire system)

Yet average 3% is the normal swing experienced 95% of the time.

BARGES

The barge type commonly has the same hull form as the ship type but it is not self-propelled. Drilling barges has the following advantages:

1. Lower cost than other floaters.2. Smaller crew and quarter needs.

Their disadvantages are as follows:

1. Low towing speeds.2. Dependence on tugs and other work boats.

Various equipment at the wellbore site used for drilling operations has divided into following categories:

1. Power-plant equipment.2. Hoisting equipment.3. Rotating equipment.4. Fluid circulating equipment.

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POWER PLANT EQUIPMENTThe power plant is the heart of the drilling rig. The power developed by the rig power plant is used principally for three operations i.e. (1) hoisting (2) rotating (3) fluid circulation. In addition to these major functions several auxiliary operations may also be powered by the rig power plant; some of them are (1) mud vibrating screen, (2) water pumps, (3) rig lighting system, (4) power for hydraulically operated blowout preventers. The power plant may be called up to perform all of these jobs simultaneously, or it may be necessary to perform only one function or a combination of functions at any one time. In any event, a principal requirement of a power plant is flexibility. The power plant must be designed so that, whenever required, either of the last two principal recipients of power can receive essentially the entire power output of the plant.

Power for drilling rig is normally furnished by internal combustion engines or electricity or any combination of these. The gas turbines may have some application in drilling-rig power plants, although they have not been used on rigs upto the present time.

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DIESEL ENGINES

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Diesel engines are deployed on the drilling and work-over rigs as a main source of power for hoisting, rotating and fluid circulation equipment, electric generation and prime mover for compressors and cranes. In high horse power range diesel engines of Caterpillar, Cummins, Alco, Daihatsu, GM etc, are mostly in use, where as in horse power range Caterpillar, Cummins, Detroit, Kirloskar are deployed.

GENERAL ENGINE CONSTRUCTION

The diesel engine is an internal combustion machine which utilizes diesel fuel to produce work.

Five principal component systems and numerous pieces of additional equipment add up to the “work”-producing part of the powertrain assembly.

THE CYLINDER BLOCK

The engine cylinder block makes up the largest single part of the diesel engine. The cylinder block contains the firing pistons, where engine work is produced. The cylinder block is symmetrical in design, and most diesel engines of the Detroit type differ principally only in the direction of rotation of the crankshaft- a clock wise motion or a counter clockwise motion.

DIESEL ENGINE EQUIPMENT

In addition to the cylinder block, pistons and crankshafts, diesel engine equipment normally includes:

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1. An oil pump2. An oil cooler3. An oil filter4. A fuel oil strainer/filter5. A fuel injector6. A fuel pump7. An air cleaner8. An air blower9. A battery10. An alternator11. A starter12. A solenoid13. A thermostat14. A heat exchanger/raw water pump, a fan/radiator, or a keel cooling system

Fuel for the operation of the diesel engine is stored in a supply tank. A fuel pump draws the fuel through a strainer. It is then forced through a filter and through fuel injection manifolds into the cylinder heads to the fuel injectors. Excess fuel is returned to the supply tank.

After passing through an air cleaner, air for cylinder firing is supplied to the cylinder by a blower which pumps the air through the cylinder ports. The blower also supplies air for “scavenging” or “blowing out” cylinder exhaust gases following combustion.

All moving parts of the engine as well as principle connecting rods and camshaft bearings require lubricating oil. The lubricating oil is drawn from the engine’s oil pan by a gear type oil pump. The oil passes through oil filter(s) and then flows to the oil cooler ultimately through the supply passages of the cylinder block and cylinder heads where it is utilized to lubricate the functional parts of the engine.

As the engine operates, heat is produced and must be dissipated to maintain engine operation. A cooling system is required by the engine to meet this need. Coolant is circulated within a closed system by a centrifugal water-pump. The coolant circulates through the engine and carries off the heat produced by the engine. Heat is removed from the coolant by either a radiator/fan, heat exchanger, or keel cooling operation. The engine temperature is regulated by a thermostat which controls the flow of the coolant through the cooling system.

THE INSTRUMENT PANEL

The instrument panel of a diesel-powered machine generally includes an oil pressure gauge, a water temperature gauge, an ammeter and a tachometer. Located nearby these gauges, the operator will be able to find the engine starting switch, the engine stop knob, an emergency stop knob, and the engine hand throttle.

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THE OIL PRESSURE GAUGE

As soon as engine begins operating, the oil pressure gauge will begin to register the pressure of the engine lubricating oil.

THE WATER TEMPERATURE GAUGE

The water temperature gauge registers the temperature of the engine coolant.

THE AMMETER

The ammeter is utilized to register the electrical current flow to and from the engine’s battery. The operator will be able to tell from the ammeter reading if the battery is receiving an electrical charge or is being discharged.

THE TACHOMETER

The tachometer registers the speed of the engine in revolutions per minute (rpm’s).

THE ENGINE STARTING SWITCH

The engine starting switch is utilized only to start the engine and must be released immediately after the engine “catches” and starts.

THE STOP KNOB

The stop knob is used, except in emergency situations, to shut down the engine. Before the knob is pulled out to stop the engine, the engine speed should be reduced to idle for a few minutes to allow the engine to “cool down”.

THE EMERGENCY STOP KNOB

The emergency stop knob prevents internal combustion by shutting off the air supply to the engine. It should be used in any emergency or when the primary stop knob fails to shut down the engine.

THE THROTTLE CONTROL

The throttle control is connected to the engine’s governor and is used by the operator to manually change the speed of the engine.

AUXILLARY ENGINE EQUIPMENTS

COLD WEATHER STARTING AIDS

Extremely cold weather reduces the efficient operation of cylinder combustion. When weather conditions are very cold it may be necessary to give the engine an “assist” when starting. Cold weather starting aids are designed to inject a highly combustible fluid into the air intake system to provide the

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assistance necessary for engine starting. Starting aids are to be used only when cold weather prevents normal starting.

GOVERNORS

Environmental operating conditions often put differing amounts of stress on engine operation. These differences would result in constantly changing speeds without the intervention of the engine governor. The governor controls the amount of fuel fed to the engine.

It is used to maintain a reasonable constant engine speed during varying load conditions. Governors will be one of three types:

1. A limiting speed mechanical governor to exercise maximum and minimum speed control with immediate speed manual control.

2. A variable speed mechanical governor to maintain a constant engine speed while allowing manual intervention.

3. A hydraulic governor to automatically maintain constant engine speed with a minimum of variation.

TRANSMISSION

The transmission provides maximum usable power between the engine and the drive mechanism.

POWER TAKE-OFF ASSEMBLY

The Power take off assembly is used to transfer power from the engine to the transmission.

The four principal component systems of the diesel engine are:

1. The fuel system2. The air System3. The lubricating system4. The engine coolant system

THE AIR SYSTEMThe air system provides air to the engine for combustion, cylinder scavenging, cooling crankcase ventilation and air-box drain. The major components of the air system are:

1. Air cleaner2. Blower

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THE AIR CLEANER

The air cleaner is the major component of the air system. Without clean air, the engine will not operate efficiently. Continued operation of an engine with a dirty air system will result in extensive damage to the engine. It provides maximum protection for the engine against dust and other forms of air contamination. In this chapter, we will discuss two basic types of air cleaners:

1. Oil-bath-type air cleaner2. Dry-type air cleaner

OIL-BATH TYPE AIR CLEANERS

The oil-bath air cleaner consists of two parts: a body and an interior element (metal wool) which filters the air and condenses the circulated oil so that only dry air enters the engine.

The condensed oil carriers the dust from the outside air to the oil cup, where it is deposited. The oil is then re-circulated. The oil-bath air cleaner is more efficient at higher engine rpm’s because the air velocity operating within it increases. The oil-bath air cleaner is less efficient at low engine rpm’s because the air velocity varies, efficiency varies.

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SERVICE AND MAINTENANCE

Service oil bath-type cleaners as follows:

1. Wash element in Kerosene or fuel oil. Blow out with compressed air. Dry completely before use.2. Wipe center tube clean with lintless cloth.3. Wash sump and baffle in kerosene or fuel oil.4. Clean and inspect gaskets.5. Fill oil cup, taking care not to overfill.

THE HEAVY-DUTY DRY-TYPE AIR CLEANER

The heavy-duty dry-type air cleaner consists of a removable cover and an air cleaner body, which contains a paper filter cartridge. This type of air cleaner uses the centrifugal force of circulating air to force dirt particles to the outside of the cleaner and eventually downward into a dust cup. Dry-type air cleaners operate efficiently at any engine rpm.

SERVICE AND MAINTENANCE

Service the dry-type air cleaner as follows:

1. Clean the filter element with compressed air.

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2. If element is oil; use light water pressure and a nonsudsing detergent. Dry completely before use.

3. Empty and wipe dust cup clean.

AIR CLEANER HEAVY-DUTY TYPE “FARR”

The heavy duty “Farr” type air cleaner also utilizes the centrifugal force of circulating air to force dust and dirt particles to the outside of the cleaner and downward into a dust and cup. The collected dust is exhausted from the dust cup by a gas aspirator and discharged into the atmosphere. Approximately 90% of the dust is extinguished in this stage. The remainder of the air then reversed in the cleaner and travels back trough the discharge tubes. It reverses direction again, is filtered once more and finally leaves the outlet port of the housing. The two-stage dry-type air cleaner, like the one-stage type operates efficiently at all engine rpm’s.

SERVICE AND MAINTENANCE

1. The first stage is self-cleaning and requires only the removal of foreign material when filter element is replaced.

2. The second-stage filter element must be replaced, not washed.3. New sealing gaskets are provided with the element. They should be used to replace the old

gaskets.

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HEAVY-DUTY DRY-TYPE “DONALDSON” AIR CLEANER

The heavy-duty-type “Donaldson” air cleaner operates in two stages. The first stage consists of a group of baffle tubes. The second stage is a paper-like, replaceable element. Dust is collected in a dust cup receptacle.

SERVICE AND MAINTENANCE

Service the heavy-duty “Donaldson” air cleaner as follows:

1. Wipe dust cup and baffle clean.2. Clean element with light air pressure.3. Wash element in water and low-sudsing cleaner. Dry completely before use.4. Inspect element for tears. Replace as necessary, after six washing, or annually.

THE BLOWER

The blower supplies air for combustion, scavenging cooling and crankcase ventilation. For combustion, the blower supplies a source of oxygen for fire. For scavenging, the blower is used to blow spent exhaust gases out of the cylinder. For cooling, the blower provides cool air to circulate over and around the piston, liner, exhaust valves harmful vapours from the crankcase and prevents crankcase vapours from etching bearings.

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THE FUEL SYSTEM

The fuel system supplies the engine with clean fuel, not only for combustion, but also to cool and lubricate the fuel injectors as it passes through them, maintains pressure via the fuel pump and purges the system of air by recirculation. The major components of the fuel system include:

1. Fuel storage tank2. Fuel injector3. Fuel pump4. Fuel filters

THE FUEL INJECTOR

The fuel injector is a simply constructed, compact unit designed to:

1. Time the injection of diesel fuel into the cylinder head

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2. Meter the fuel to provide the proper amount for controlled combustion.3. Pressurize the fuel efficient injection.4. Atomize the fuel by forcing it under pressure trough tiny opening in the spray tip.

FUEL INJECTOR SERVICE

Because the opening in the spray tip of the fuel injector are so small, most fuel injector problems are caused by difficulties with dirt particles. Therefore, when servicing the fuel injectors, it is important to observe a few precautions.

1. Provide as clean a work area as possible. Keep it dust-free and non-contaminated.2. Wash all parts of the fuel injector with clean fuel oil only and dry with clean, dust-free

compressed air. Never use shop rags for cleaning.

THE FUEL PUMP

The fuel pump plays the important dual roles of supplying the fuel requirements of the engine under all operating conditions and of maintaining sufficient pressure in the system to transfer fuel from the fuel tanks to the fuel injectors. The pump also circulates excess fuel trough the injectors, thereby cooling them and purges the system of air by re-circulating the unused portion of fuel.

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FUEL PUMP SERVICE

When servicing the fuel pump, keep in mind the following inspection points:

1. Clean all parts in clean fuel oil and thoroughly dry with compressed air2. Do not attempt to reuse oil seals. The old seals must be discarded and new sales used for

replacement3. Check the gear teeth, ball slot, drive and driven shafts for wear or chipping 4. Make sure the pump body and cover fir together snuggly and without scratches or scoring

where leaks might occur

THE FUEL STRAINER AND FUEL FILTER

The fuel strainer is also called the primary filter. It is located between the fuel tank and the fuel injector. The fuel filter fits between the fuel pump and the fuel manifold. Both the fuel strainer and the fuel filter are used to remove any impurities that might be in the fuel before it reaches the cylinder for combustion.

The filter and strainer are essentially the same in construction and comprises an outer body, a cover and a replaceable paper filtering element.

FUEL FILTER SERVICE

Fuel filter service includes only a few basic steps.

1. Remove and discard the paper element and gasket.2. Clean the outer body and cover in clean fuel oil and dry with compressed air.3. Replace the old element and gasket with a new element and gasket.

PREVENTIVE MAINTENANCE FOR ENGINES

OIL LEVEL

Check the oil level daily before starting the engine. Add oil, if necessary, to bring it to the proper level on the dipstick.

Select the proper grade of oil in accordance with the instructions given in the lubricating oil specifications, accompanying the engine.

New engines should be started with 100-hour –oil-change periods. The drain interval may then gradually be increased or decreased to establish the most practical oil change period for the particular service.

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OIL FILTER ELEMENTS

Install new oil filter elements and gaskets each time the engine oil is changed. Check for oil leaks after starting the engine.

COOLANT LEVEL

Check the coolant level daily and maintain it near the top of the heat exchanger tank or radiator upper tank.

Clean the cooling system every 6 months using a good radiator cleaning compound in accordance with the instructions on the container. After the cleaning operation, rinse the cooling system thoroughly with fresh water, adding a good grade of rust inhibitor or a high-boiling-point-type antifreeze. With the use of a proper antifreeze or rust inhibitor, this interval may be lengthened until, normally, this cleaning is done only in the spring or fall. The length of this interval will, however, depend upon an inspection for rust or other deposits on the internal walls of the cooling system. When a thorough cleaning of the cooling system is required, it should be reverse flushed.

If the cooling system is protected by a coolant filter and conditioner, the filter element should be changed every 500 hours or 2 months.

COOLING SYSTEM HOSES

Inspect all of the cooling system hoses at least once every 500 hours or 2 months for signs of deterioration. Replace the hoses if necessary.

EXTERIOR RADIATOR CARE

Inspect the exterior of the radiator core every 1,000 hours or 4 months and, if necessary, clean it with a quality grease solvent and dry it with compressed air. Do not use fuel oil, kerosene or gasoline. It may be necessary to clean the radiator more frequently if the engine is being operated in dusty or dirty areas.

WATER IN HEAT EXCHANGER

Every 500 hours, drain the water from the heat exchanger raw water inlet and outlet tubes. Then, remove the zinc electrodes from the inlet side of the raw water pump and the heat exchanger. Clean the electrodes with a wire brush or, if they are worn excessively, replace with new electrodes. To determine the condition of a used electrode, strike it sharply against a hard surface; a weakened electrode will break.

Drain the cooling system, disconnect the raw pipes at the outlet side of the heat exchanger, and remove the retaining cover every 1,000 hours and inspect the heat exchanger core. If a considerable amount of scale or deposits are present, cleaning must be performed by a qualified repair shop.

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FUEL TANK

Keeping the fuel tank filled keeps condensation to a minimum. Select the proper grade of fuel in accordance with the diesel fuel oil specifications accompanying the engine. Open the drain at the bottom of the fuel tank every 500 hours, or when necessary to drain off any water or sediment.

FUEL FILTER

To remove sediment and water, drain approximately one-fourth pint of fuel from the strainer daily.

NEW ELEMENTS

Install new elements every 7 days or when plugging is indicated. The fuel pressure at cylinder head fuel inlet manifold and the inlet restriction at the fuel pump will determine when elements need to be changed. In a clean system, the maximum pump inlet restriction must not exceed six inches of mercury.

SLUDGE IN OIL-BATH-TYPE AIR CLEANERS

Remove the dirty oil and sludge from the oil-bath-type air cleaner cups and centre tubes every 8 hours, or less if operating conditions warrant. Wash the cups and elements in clean fuel oil and refill the cups to the level mark with the same grade of heavy-duty oil as used in the engine. The frequency of servicing may be varied to suit local dust conditions. The body and fixed element in the heavy-duty-oil-bath-type air cleaner should be serviced every 7 days or as conditions warrant.

AIR BOX DRAIN

With the engine running, check for flow of air from the air box drain tubes every 1,000 hours. If the tubes are clogged, remove, clean and reinstall the tubes. The air box drain tubes should be cleaned periodically even though a clogged condition is not apparent.

VENTILATING SYSTEM

Lean the crankcase breather, if it is mounted on the flywheel housing, every 1,000 hours. Remove the crankcase breather from the engine and wash with steel mesh pads in fuel oil and dry them with compressed air. This cleaning period may be reduced or lengthened according to severity of service.

ALTERNATOR

Inspect the terminals for corrosion and loose connections. Check the wiring for frayed insulation.

TACHOMETER

Lubricate the tachometer drive every 1,000 hours with an all purpose grease at the grease fitting. At temperatures above +30degree Fahrenheit, use No.2 grade grease. Use No.1 grade grease below this temperature.

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THROTTLE CONTROL

Lubricate the throttle control mechanisms every 7 days with an all purpose grease at the grease fitting. At temperatures above +30degree Fahrenheit, use No.2 grade grease. Use No.1 grade grease below this temperature. Lubricate all other control mechanisms as required, with engine oil.

DRIVE BELTS

New drive belts stretch after first installation. To make sure of the proper fit, operate the engine for a few seconds after installation of new belts. This will seat the belts in position and will enable the operator to set the correct amount to tension on the belts. If the belt is too loose, it will slip. If the belt is too tight, engine damage may result. Adjust the belt so that firm pressure applied halfway between the two pulleys will result in belt depression between one-half and three-fourth inches.

When one belt is worn, replace all belts of the set. Use only a matched set for replacement. After thirty minutes of operation and again after eight hours of operation, check all belts, and retighten if necessary.

TURBOCHARGER

There is no scheduled interval for performing an inspection of the turbocharger. As long as turbocharger is operating satisfactorily and there is no appreciable loss of power, only a periodic inspection is necessary.

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HOISTING EQUIPMENTOnce rigging up has been accomplished, drilling operations are begun. The long strings of pipe, casing, and drill collars used in well drilling operations often total as much as 25 tons of weight. To lift, or hoist, these pieces of equipment require great amounts of energy produced by diesel or electric power. This energy is transmitted into work production by the rig drawworks.

Other pieces of hoisting equipment include hooks which are used for various pulling functions, snatch blocks which are used for temporary hoisting jobs and elevators which are attached to sucker rods, tubing, and pipes to hold them during hoisting and lowering operations. Here we shall individually discuss those pieces of equipment directly associated with hoisting operations.

DRILLER’S CONSOLE

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TYPICAL POWER FLOW DIAGRAM: - ENGINE-POWERED DRAW-WORK

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DRILLING RIG DIAGRAM

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DRAWWORKS

The drawworks depends upon a system of brakes, clutches, chain drives, couplers and catheads to control hoisting operations. From the drawworks, special wire rope lines are strung over a crown block at the top of the derrick, through a travelling block and other hoisting equipment, and are finally attached to the drilling bits, pipes, tunings, etc., for drilling operations.

A drawworks comprises a large revolving drum (around which drilling line is wound), the catshaft (to which the catheads are mounted), and a series of shafts, clutches and chain and gear drives for changing speed and operation direction (forward and reverse).

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DRAWWORKS BRAKES

Oilfield drawworks and hoists use exterior-band type brakes.

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HYDROMATIC BRAKES

The hydromatic brake of retarder is a hydrodynamic device that absorbs power by converting mechanical energy into heat within brake fluid. The hydromatic brake acts as a retarder only and will reduce the input speed, but won’t bring the input speed to a complete stop. This must be handled by the main brake.

SPEED REDUCERS

Speed reducer gears give the operator the ability to control speed changes and reverses on the drawworks drum brake and hydromatic brake. They can be either chain-driven or gear-driven.

E.g. two speed chain drive

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CATHEADS

The catheads are installed on the catshaft at both ends of the drawworks. One cathead is generally simple drum-type cathead used for light hoisting duties performed by rope and muscle power. The other cathead is an air-actuated mechanical device with modulating air valves to permit the driller precise control in exerting pulls on tonging or spinning lines.

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CHAIN DRIVES

Chain drives should be periodically inspected for proper alignment, tensioning and lubrication. Misalignment of the chain drive will cause uneven loading across the width of the chain. To ensure proper alignment, drive shafts must be parallel and level and the sprockets that hold the chain must be properly aligned on the parallel shafts.

AIR CLUTCHES

Air clutches are used in various positions in the drawworks and drive groups to engage and disengage power transmission to the individual rig component. The air clutch is actuated by air pressure which closes quick-release valves. This air pressure is furnished by the air compressing unit of the rig. The air is introduced into a diaphragm chamber which forces a pressure plate forward to compress the release springs holding the clutch in the disengaged position. Disengagement is accomplished by reducing air pressure to the clutch.

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Maintenance of air clutch includes checking:

1. Air lines for restriction of leaks2. Operating valve for full operating3. Air leakage at the quick release valve or at the diaphragm

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WIRE LINE, TUBING LINE AND SAND LINE

Drilling lines arrive at the rig-site either in a coil or wound on a reel. Stringing up operations involve “stringing” the free end of the rope over the crown block, through the travelling block and other hoisting equipment, and attachment of the line to the drawworks drum.

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CROWN BLOCK

It is a sheaved pulley located at the top of the drilling rig to provide a leverage point for wire line stringing. The sheaves of the pulley are mounted on roller bearings which are individually lubricated through grease fittings at the end of the crown shaft. The shaft assembly is bolted to the uppermost section of the rig frame.

The drilling cable is rolled over the sheaves of the crown block alternatively with the sheaves of the travelling block.

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TRAVELLING BLOCK

A travelling block is also a sheaved pulley, but is the “travelling” or free moving agent of the crown

block/travelling block arrangement. The travelling block moves up and down as it hangs in the derrick

and is used to pull drill pipe and casing, as well as to hold the power swivel for drill pipe turning.

HOOKS

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Hooks are attached to travelling blocks with large shackles, and are used for various pulling functions of the rig. Small-capacity hooks are used to handle tubing and sucker rods. Larger capacity hooks are designed to carry heavier loads ranging from 100 to 650 tons. Such hooks are equipped with a strong interior spring and/or hydraulic snubber assembly to help absorb load shock developed by drilling operations.

CARE AND MAINTENANCE OF MECHANICAL BRAKES AND DRAWWORKS

The mechanical self energizing friction brake on the drawworks is a critical item and a better understanding of construction and maintenance will help a long way for better rig utilization.

The rims are subjected to friction, wear and tear. The rims are girdled by brake blocks mounted on a flexible steel band. The bands are anchored at one end (dead end) to an equalizer beam, and the other end pinned to the brake lever (live end) through a rod and toggle mechanism.

When the brake lever is engaged, the live end of the band is pulled, resulting in gripping of rim by the brake blocks. The amount of grip slows down or stops the rotation of drum. The grips on the two rims are equalized for smoother braking by the equalizer-beam through two heavy duty adjustable hold-down bolts. The band brakes are said to be self energizing since the friction force includes increasing tension on the band along the circumference, with maximum gripping force towards anchor-end or dead-end. Once released, the brake returns to an original position, against rollers maintaining a uniform gap from the rim.

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STORAGE AND PERSERVATION

The brake rims also require due attention.

1. Store the brake rim flat on its side with the bolt up flange on top for handling. This will avoid the risk of egg-shaping.

2. Drain water from jacket on an idle rig to avoid rusting in warm conditions and cracking in freezing conditions.

3. Cover the rims with greased oil papers to prevent rusting.

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ROTATING EQUIPMENTS “Rotating Equipment” refers to the pieces of equipment in drilling operations which actually rotate or which impart rotating motion to the drill pipe. Rotating operations begin with a swivel hung from the travelling block/hook, drill pipe and collars, down to the drill bit.

THE SWIVEL

The swivel performs three functions:

1. It suspends the Kelly2. It allows for rotation of the Kelly and the drill string3. It provides a connection for the rotary hose to allow passage of the drilling fluid into the Kelly

and drill string

THE KELLY

The Kelly is a square-shaped or hex-shaped pipe that transmits power from the rotary table to the drill bit. Also, drilling mud is pumped downhole and returned through the Kelly.

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HEXAGONAL KELLY

SQUARE KELLY

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The Kelly should be periodically inspected and replaced when it is cracked or bent, or if fatigue has set in at each end (where the flats join the upsets) or in the centre. The Kelly should also be replaced when the corners become rounded from wear.

ROTARY TABLE

The rotary table provides the initiation of rotary movement of the Kelly. The master bushing of the rotary table encases the Kelly bushing. As the rotary table turns the master bushing, the Kelly, drill pipe and the drill bit also turn.

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DRILL COLLARS

The drill collars provide additional weight to drilling bits. This extra weight helps in keeping the drill pipe in tension and, thus, held straight during drilling.

HOLE OPENERS

Initial hole is accomplished by drill bits. Circulation pressure moves the cutters and the bottom of the bit upward, opening them for drilling operation.

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FLUID CIRCULATION EQUIPMENTDrilling mud, often called drilling fluid, is primarily used to remove small chips of rock and debris from hole as it is drilled. It also cools and lubricates the drill bit, and applies pressure in the hole to keep it from caving in and to keep formation pressure from causing a blowout.

Below fig. shows a typical rotary rig fluid circulation system:

Mud typically travels through the mud system in the following sequence:

1. From mud pit to slush pump2. From slush pump to stand pipe/Kelly hose/swivel3. From standpipe/Kelly hose/swivel to Kelly

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4. From Kelly to drill bit/string5. From drill string/bit up the annular space6. Up the annular space through the BOP stack

BOP (Blow Out Preventer)

7. Through the BOP stack to the return line8. From return line to shale shaker9. From shale shaker to settling pit10. From settling pit to sump (storage)pit

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THE SLUSH PUMP

Slush pumps circulate drilling fluid through the mud circulation system. They consist of two main components. The larger section is the power end of the pump (an interior view of the power end is), which transfers power form the drive engine (diesel or electric) to the pump crankshaft. The smaller section is the fluid end, which actually pump the fluid. If the pump has three cylinders, it is called a triplex pump. A two- fluid cylinder pump is called a duplex pump.

CENTRIFUGAL PUMP

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Centrifugal pumps are used to ensure a continuous supply of mud to the slush pump, or for mud mixing operation. Many centrifugal pumps have, around the drive shaft, a seal that is designed should not be considered defective unless leakage is excessive.

MUD TANKS

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Mud tanks hold drilling fluids at various sites around the mud circulating system, such as the suction pit, the circulating pit, or the settling pit. The tanks are approximately 26 feet long by 8 feet wide by 6 feet deep.

Slush Pump Troubleshooting

Possible Cause Remedy

Knocking in Fluid End

Restricted suction line Remove and clean

Air entering suction line Cheek cut-off valve, all connections

Low fluid level fill to proper level

Worn valves Inspect and repair

Suction line too small Replace with larger size

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Knock in Power End

Worn crosshead ReplacePin/ connecting rodWorn main bearing ReplaceLoose plunger/intermediate Tighten, or replace if damagedRod/crosshead connection

Rapid Valve Wear/Failure

Knocking in fluid end See KNOCKING IN FLUID ENDAbove

Corrosion Treat fluidAbrasives Filter

MUD AGITATOR

Mud pit agitators maintain drilled in suspension to aid solids removal at the desander and desilter. The mud agitator also helps prevent weight material settling and mud channeling.

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SHALE SHAKER

Drilling fluid withdrawn from the well bore comes up to the surface filled with different size cutting or rock chips. The shale shaker removes the larger bits from the circulating mud and passes the mud on to the mud sump or to a desanding unit.

THE DESANDER

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When drilling in sandy regions, desanders are used to remove sand from the circulating fluid. The desander enhances drilling efficient in several ways: (1) it reduces chemical treatment/mud cost; (2) it increases bit life and penetration rates; (3) it reduces differential sticking; and (4) it reduces downtime otherwise caused by pump abrasion.

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DESILTER

In some drilling operations a desilter is used to remove fluid- thickening silt from the circulating mud to make fluid flow more freely. The desilter eases drilling and reduces downtime caused by pump wear. It also increases drilling efficiency by reducing mud weight and by reducing the occurrence of wall-stuck drill pipe.

DEGASSER

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The degasser removes virtually all gases from the drilling fluid and vents them into the atmosphere at a safe distance from the drilling rig. The degasser also reduces the threat of well blowout.

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