An Introduction to Drilling

Akshat Tarate

Summer Trainee

New Builds Division - EOSIL

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Topics to be covered

● What is Drilling● Components of Drilling● Drilling Systems● Well Control Systems● Circulation Systems● Drillstring Components● Drilling Process

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Times change

An Event of Joy turning into a BIG Problem!!!

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Global Disaster

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What is Drilling

● It is a process of creating a hole in the given work-piece of a certain diameter

● In our case it is a process of creating a hole in the earth to provide a conduit for the production of oil and gas.

Components of a Drilling Rig

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Components of a drilling rig

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Power System

Horse Power of Rig?

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Hoisting System

● The hoisting system is a large pulley system which is used to lower and raise equipment into and out of the well such as– Drillstring– Casing

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Swivel

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Drawworks

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Hoisting System

● Drawworks– The drawworks consists of a large revolving drum, around which

the drill line is spooled. The drum of the drawworks is connected to an electric motor and gearing system.

● The drilling line is reeved over a set of sheaves in the top of the derrick, known as the crown block and down to another set of sheaves known as the travelling block.

● A large hook with a snap-shut locking device is suspended from the travelling block. This hook is used to suspend the drillstring. A set of clamps, known as the elevators, used when running, or pulling, the drillstring or casing into or out of the hole, are also connected to the travelling block.

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Derrick

● It is the structure used to support the crown blocks and the drillstring of a drilling rig.

● It is the true load bearing structure of a Land rig.

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Derrick

Drilling Systems

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Kelly Drive Systems

● It consists of the following components– Kelly– Kelly Bushing– Rotary Table

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Kelley

● The kelly is the first section of pipe below the swivel. It is normally about 40‘ long, and has an outer hexagonal cross-section. It must have this hexagonal shape to transmit rotation from the rotary table to the drillstring.

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Rotary Table

● The revolving or spinning section of the drillfloor that provides power to turn the drillstring in a clockwise or anticlockwise direction.

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Kelley Bushing

● An adapter that serves to connect the rotary table to the kelly. The kelly bushing has an inside diameter profile that matches that of the kelly, usually square or hexagonal. It is connected to the rotary table by four large steel pins that fit into mating holes in the rotary table.

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Top Drive

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Top Drive Systems

● A top drive system consists of a power swivel, driven by a 1000 hp dc electric motor.

● This power swivel is connected to the travelling block and both components run along a vertical guide track which extends from below the crown block to within 3 metres of the rig floor. The electric motor delivers over 25000 ft-lbs torque and can operate at 300 rpm.

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Well Control system

● Blow Out Preventer– BOPs are basically high

pressure valves which seal off the top of the well. On land rigs or fixed platforms the BOP stack is located directly beneath the rig floor.

● Types of BOP– Annular BOP– Ram Type BOP

• Pipe Ram BOP• Shear Ram BOP• Blind Ram BOP

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Annular BOP

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Ram Type BOP

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Kill and Choke Manifold

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BOP Accumulator System

Mud Circulation System

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Mud Circulation System

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Hopper

Works on the Venturimeter System

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Mud Pits

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Mud Pump

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Shale Shaker

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Centrifuge

Drilling String Components

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Drill Bit

● The tool used to crush or cut rock. Everything on a drilling rig directly or indirectly assists the bit in crushing or cutting the rock.

● The bit drills through the rock by scraping, chipping, gouging or grinding the rock at the bottom of the hole.

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Drill Collar

● Drill collars are tubulars which have a much larger outer diameter and generally smaller inner diameter than drillpipe.

● The function of drill collars are:– To provide enough weight on bit for efficient drilling– To keep the drillstring in tension, thereby reducing bending

stresses and failures due to fatigue.– To provide stiffness in the BHA for directional control.– To Provide Weight on Bit (WOB)

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Heavy Weigh Drillpipe

● Heavy wall drillpipe (or heavy weight drillpipe) has a greater wall thickness than ordinary drillpipe and is often used at the base of the drillpipe where stress concentration is greatest. The stress concentration is due to:

– The difference in cross section and therefore stiffness between the drillpipe and drillcollars.

– The rotation and cutting action of the bit can frequently result in a vertical bouncing effect.

● The HWDP is used to absorb the stresses being transferred from the stiff drill collars to the relatively flexible drillpipe.

● The major benefits of HWDP are:– Increased wall thickness– Longer tool joints– Uses more hard facing– May have a long central upset section

● It should always be operated in compression. More lengths of HWDP are required to maintain compression in highly deviated holes.

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Drill Pipe

● Drillpipe is the major component of the drillstring It generally constitutes 90-95% of the entire length of the drillstring.

● The Drillpipe is a seamless pipe with threaded connections, known as tool joints.

● At one end of the pipe there is the box, which has the female end of the connection. At the other end of each length ofdrillpipe is the male end of the connection known as the pin.

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Stabilizer

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Stabilizers

● The function of the stabiliser depends on the type of hole being drilled. In vertical holes the functions of stabilisers may be summarised as follows:

● Reduce buckling and bending stresses on drill collars● Allow higher WOB since the string remains concentric

even in compression.● Increase bit life by reducing wobble.● Help to prevent wall sticking.● Act as a key seat wiper when placed at top of collars.

Drilling Process

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30” Conductor

● It is placed by three ways– Drilling a 36” hole and placing a 30” conductor– Pile Driving (done in the desert areas and offshore)– Jetting (done offshore)

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Piling of a 30” Conductor

● The conductor is then driven to refusal.● Refusal is defined as the number of hammer blows per

foot of penetration● The conductors are usually welded and driven.

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Working of Diesel Pile Driver

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Drilling a 26” Hole

● The hole can be drilled in two ways– Drill the hole with 26”

bit– Drill a 17½” hole and

underream it to 26”

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Installation of 20” Casing

● The casing bowl is then set on the rotary table

● The elevators are prepared

● The float collar and float shoe is made into the casing string and lowered

● The casing is then cemented

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Drilling a 17 ½” Hole

● For drilling this hole we generally use a 21 ¼” annular BOP.

● The BOP has to comply to API 16A.

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13 3/8” Casing Job

● The 17 ½” section is drilled, 13 3/8” casing is run in hole and cemented in place.

● The wellhead is then bolted on top of the Surface casing wellhead.

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Drilling 12 ¼” Hole

● The Mud is prepared and 12 ¼” BHA is made up and run in the hole

● LOT are carried out to find out the Formation Integrity

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Recommended BOP configuration

● 13 5/8” Annular● 13 5/8” Double Ram

– Pipe Ram– Shear Ram

● 13 5/8” Pipe Ram

13 5/8” Pipe Ram BOP

13 5/8” Annular BOP

13 5/8” Shear Ram BOP

Drilling Spool

13 5/8” Pipe Ram BOP

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9 5/8” Casing

● After the hole section is drilled, 9 5/8” production casing is run, hung off in the wellhead, cemented and pressure tested.

● The entire production casing is then pressure tested to maximum expected tubing pressure (METP)

● This casing goes to around 10000 ft.

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Drilling a 8 ½”Hole

● A 8 ½” BHA, with the same configuration as for the 12 ¼” BHA, is normally used to drill through the production casing cement shoe and the reservoir to well target.

● FIT/LOT are carried out

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7” Liner Job

● The 7" liner is made up and run in hole on a running string.

● The liner will typically be hung off with a 100 to 150m overlap into the production casing.

● The Liner is also Cemented in place

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Thank YouAny Questions??