Drilling Technology

Types of Drilling Rigs

Land Rig(Onshore)

When a drilling project is commenced, two goals are governing all aspects of it. 1. The first is to realize the well in a safe manner (personal

injuries, technical problems) 2. The second one is to complete it with minimum

Cost

For making hole, different technologies have been invented (We Focus on Rotary Drilling Technology) Percussion drilling With mud -> Quick percussion drilling Without mud -> “Canadian drilling”

Rotating bit Full cross-section drilling

Surface driven Rotary drilling Rotary nozzle drilling

Subsurface driven Turbine drilling

Positive displacement motor drilling Electro motor drilling

Annular drilling Diamond coring Shot drilling

Abrasive jet drilling Cavitating jet drilling Electric arc and plasma drilling Electric beam drilling Electric disintegration drilling Explosive drilling

Flame jet drilling Implosion drilling Laser drilling REAM drilling Replaceable cutter head drilling Rocket Exhaust drilling

Spark drilling Sub terrene drilling Terra drilling Thermal-mechanical drilling Thermo corer drilling

Tool Pusher

The tool pusher supervises all drilling operations and is the leading man of the drilling contractor

on location. Along with this supervision duties, he has to co-ordinate company and contractor

affairs.

Company Man

The company man is in direct charge of all the company’s activities on the rig site. He is responsible

for the drilling strategy as well as the supplies and services in need. His decisions directly effect

the progress of the well.

Driller

The driller operates the drilling machinery on the rig floor and is the overall supervisor of all

floor men. He is directly responsible to the tool pusher and is the person who is most closely

involved in the drilling process. He manipulates from his position at the control console on the

rig floor brakes, switches, levers and other related controls that influence the drilling parameters.

In case of a kick he is the first person to take action by moving the bit off bottom and close the

BOP.

Floor Man and Roustabout

During tripping, the rotary helpers are responsible for handling the lower end of the drill pipe as

well as operating tongs and wrenches to make or break a connection. During other times, they

also maintain equipment, keep it clean, do painting and in general help where ever help is needed

Derrick Man

The derrick man works on the so-called monkey board, a small platform up in the derrick, usually

about 90 [ft] above the rotary table. When a connection is made or during tripping operations he

is handling and guiding the upper end of the pipe. During drilling operations the derrick man is

responsible for maintaining and repairing the pumps and other equipment as well as keeping tabs

on the drilling fluid.

Mud Engineer, Mud Logger

The service company who provides the mud almost always sends a mud engineer and a mud logger

to the rig site. They are constantly responsible for logging what is happening in the hole as well

as maintaining the proper mud conditions.

According to a wells final depth, it can be classified into:

Shallow well: < 2,000 [m]

Conventional well: 2,000 [m] - 3,500 [m]

Deep well: 3,500 [m] - 5,000 [m]

Ultra deep well: > 5,000 [m] With the help of advanced technologies in MWD/LWD and extended reach drilling

techniques

horizontal departures of 10,000+ [m] are possible today (Wytch Farm).

Land Rigs

The parts of the rig can be grouped into five

systems:

Power

Rotating

Hoisting

Circulating

Control and measurement

The bit is the main critical item of a drilling operation.

This does not mean that the bit can make hole alone.

To select a bit, some information must be known about the nature of the rocks to be drilled

Drill stem consists of three main components:

drill collars,

drill pipe and

Kelly.

The following are the principal functions of

the drill stem:

1. Drill stem lowers the bit into the hole and

withdraws it

2. Part of the drill stem puts weight on the bit so

that the bit can penetrate the formations more

effectively

3. Drill stem transmits a turning, or rotating,

action to the bit.

4. Drill stem conducts the drilling fluid under

pressure from the surface to the bit.

The traveling block, crown block and wire line

are the three components.

The main function is to connect the supporting

derrick or mast with the load of pipe to be lowered

into or withdraw from the hole.

Traveling block is a free moving section of a block and tackle that contains a set of pulleys or sheaves through which the drill line is threaded or revved and is opposite (and under) the crown block (the stationary section).

A crown block is the stationary section of a block and tackle. It contains a set of pulleys or sheaves which the drill line (wire rope) is threaded or revved and is opposite and above the traveling block.

A mast is also called the standard mast. It is a structure with four supporting legs resting on a square base, the entire work area of the floor is in the derrick square.

In contrast, the mast is much slenderer and may be thought of as sitting on one side of the derrick floor or work space.

The two main purposes of the

draw works are:

To lift the pipe out of the hole

To lower the pipe back into of the

hole.

Blowout preventer (BOP) is

the equipment associated with

a rig and devices installed at

the wellhead to prevent fluids

and gasses from

unintentionally escaping from

the borehole.

Centrifuge is the equipment

which is used to separate fine

silt and sand from the drilling

fluid.

It is used to provide clockwise rotational force to facilitate the process of drilling a borehole

Operating through drive bushings, the rotary rotates the Kelly and, through it, the drill stem and the bit

MAIN FUNCTIONS OF A ROTORY TABLE

To rotate the drill stem

To hold devices called slips that support the weigh of the

drill stem when the latter is not supported by hook and

elevators.

Kelly is a long square or hexagonal steel bar

with a hole drilled through the middle for a

fluid path.

The Kelly is used to transmit rotary motion

from the rotary table or Kelly bushing to the

drill string while allowing the drill string to be

lowered or raised during rotation.

The Kelly goes through the Kelly bushing,

which is driven by the rotary table.

The Kelly bushing has an inside profile

matching the Kelly’s outside profile (either

square or hexagonal), but with slightly larger

dimensions so that the Kelly can freely move up

and down inside.

Swivel is a mechanical device that must

simultaneously suspend the weight of the drill

string, provide for rotation of the drill string

beneath it while keeping the upper portion

stationary, and permit high-volume flow of high-

pressure drilling mud from the fixed portion to the

rotating portion without leaking

MAIN FUNCTIONS Support the load of the

drill stem

Allow rotation of the

drilling assembly

Provide a passageway for

fluid under high pressure

to enter the drill stem.

Power is provided to the rig by diesel engines, diesel-electric engines, or in some cases, butane engines. Power is transferred from the engines to the different rig systems by belts, chains, and drive shafts on a mechanical rig, or by generated DC electrical power on an electric rig. Power is distributed to the rotary table and mud pumps (34 in Figure 1) while drilling and to the draw works (15) when tripping.

he hoisting system includes the parts of the rig that are used to raise the drill stem. The hoisting gear parts include the draw works (15 in Figure 1), crown block (1), and traveling block (4). The draw works is a large winch on which the drill line spools. The drill line is wire rope that is strung between the crown block (a pulley located at the top of the derrick), the traveling block, and the draw works. The drill line can be strung in multiples for a total of 4,6, 8, 10, or 12 lines. More lines means more lifting capacity but a slower running speed. The drill line needs to be “cut and slipped” at periodic ton-miles to distribute the line wear and stress. A weight indicator (16) is attached to the drill line so that the driller can measure the drill string, slack-off, and pick-up weights. This information helps determine the amount of hole friction and the correct amount of weight to put on the bit. The draw works also transfers power to make up and break out the drill string via the tongs (13 and 14).

The derrick supports the crown block and provides a place to stack pipe that is pulled out of the hole. The depth rating of the derrick is related to the size of the rig. The height of the derrick is commonly referred to in multiples of pipe joints (a joint of pipe is approximately 30 ft long). Rigs that can stack double joints of drill pipe are called double derricks, and those that stack three joints are called treble derricks. Part way up the derrick are the monkey board (3) and pipe fingers. The derrick man handles the top end of each stand of pipe from the monkey board during trips. The pipe is racked in the finger boards and tied off to keep it from falling. The derrick substructure (23), the platform under the derrick, is rated by set back capacity; that is, the weight of the drill string stacked in the derrick plus the weight of casing that can be lifted. The height of the substructure is dictated by the height of the blowout preventers (38). The top of the substructure is called the derrick floor. This is the primary working area of the rig.

The catwalk is the deck located to the side of the derrick floor and between the pipe racks (22). Joints of drill pipe and casing are rolled from the pipe racks where they are stored on the catwalk and hoisted up through the slide (21) and V-door. The catwalk is also the primary location to process core and assemble wire line logging tools.

Circulation of drilling fluid (mud) serves several functions on a rig, including cooling the bit, providing hole stability, and aiding in formation evaluation.

Drilling fluid is circulated by the mud pumps (34 in Figure 1). The volume of mud being pumped is measured by the stroke counters, and the rate of movement is recorded by the stand pipe pressure. The stand pipe connects the mud pumps to the kelly hose. The kelly hose is connected to the swivel (6) on top of the kelly. Mud is pumped down the drill string through the bit and up the annulus or “back side” (the space between the drill pipe and the borehole). Returning mud flows down the flow line (24) into a surge tank (possum belly) and across the shale shakers (25). Shale shakers are vibrating screening devices that are designed to shake so as to separate out the drill cuttings from the mud. The shale shakers are the first place that drill cuttings can be examined and where the gas is extracted from the mud (27 and 28) (Figure 2). After going through the shake shakers the mud passes through a series of tanks or pits where the finer solids are removed via desanders (32), desilters (31) and centrifuges (33), and the mud properties are adjusted. Pits are named for their function (e.g., shale pit, settling pit, volume pit, mixing pit, and suction pit). The mud pumps are charged from the suction pit. Excess mud can also be diverted from the metal mud pits into a large, plastic lined reserve pit (29) located to the side of the rig.

The blowout preventers (BOPs) (38 in Figure 1) are the major component of the control system on a rig, and they are the last line of defenses against a blowout. The BOPs are bolted to the wellhead and are not removed until the well is completed and production equipment is installed. BOPs usually have at least four sections:

Annulars are large, hard rubber slips that fit around any sized pipe. The size flexibility, however, is at the expense of the pressure rating.

Pipe rams are metal donut-shaped sealing mechanisms that fit only a specific sized pipe but at a high pressure rating.

Blind or shear rams are edged high-carbon steel sealing mechanisms that can cut pipe and close the hole completely.

Crossover spools are metal junctions where the choke and kill lines attach.

Additional control equipment includes the kill line, choke line, and flare line. The kill line is used to pump mud into the annulus at the crossover spool in the event that heavier mud is needed to control wellbore pressures. The choke line also helps control wellbore pressures by allowing drilling mud to circulate through a choke manifold (26) (which is a set of backpressure valves). The mud and gas can then be sent down the flare line for disposal or burning in the reserve pit (29).

Monitoring and measurement of the basic functions of the rig are usually made from the driller's console (17) located on the derrick floor. From this console, the driller can monitor equipment, distribute power, change gears, and oversee crew activities. Additional measurement equipment and records are located in the dog house (18) or service shed. The dog house is located to the side of the rig floor and contains the geolograph, a device that makes a time-based chart record of several rig functions, including the following:

Kelly height or rate of penetration (ROP) (in ft/hr, m/hr, or min/ft)

Depth (in ft or m)

Pump pressure (in psi)

String weight (in thousands of lb)

Rotary speed (in rpm)

Rotary torque (in ft-lb)

Stroke rate (in strokes/min)

Circulation rate (in gal/min)

Personal safety equipment Hard hat Safety shoes Safety glasses Hearing protection The following are recommended: Well-fitted, protective clothing CPR and first aid training Do not have the following: Long shoe strings Floppy gloves Neckties or fringes Jewelry Long, loose hair A bad attitude