Drilling is not only for producing pore fluids (oil, water, gas) but also for: Gaining information about the sub-surface;

-Allowing injection of fluids;

-Exploiting geothermal resources;

-Disposing Waste (nuclear waste);

-Drilling training/research wells.

There are six basic reasons for drilling a well. 1. Information from sub surface is required. This may be to identify hydrocarbon reservoirs, coal seams or other mineral deposits.

2. Allow fluids to be produced from within the Earth. Hydrocarbons are a valuable resource but wells are also drilled for water in arid areas.

3. Allow fluids to be injected underground. Within an oil reservoir, it is sometimes necessary to pump in water to maintain reservoir pressure as oil is produced.

4. Where high downhole temperatures are present at reasonably shallow depths, water can be pumped in to the well to generate steam. The steam drives a turbine to generate electricity.

5. In geologically stable areas, wells may be drilled to dispose of nuclear waste which requires long term safe isolation.

6. Wells may be drilled for training. These wells allow students to practice tripping pipe or casing. Some include a facility to inject fluids at the bottom of the well to simulate a kick.

Objectives of Drilling Operations -Minimize the total well cost (i.e. maximize return on investment)

-Drill a useable hole (minimize formation damage)

-Drill well in a safe and environmentally sound manner.

Classifications of Rigs:In general, there are three locations: onshore, swamp or offshore/deepwater/ultra https://o.quizlet.com/ZORuEDBkf6ONHMc-.3iw2g_m.png

Land Rigs - (Heavy Land Rig) -Capable of drilling deeper than 10,000-ft

-Typical derrick load is greater than 1,000,000 lbf

-BOP rating greater than 10,000 psi

Land Rigs - Helicopter Portable -Breaks down into small packages for moving (6000 lbf max)

-Can deploy in locations not otherwise useable without very high cost (jungle, mountain tops, inaccessible locations)

Bottom Supported Marine Rigs: #1. Platforms -Self contained rig installed on platform

-Once drilling finished, rig can be removed or

replaced with small workover rig

-Can be "tender supported" like the one on the left

2. Jack up Rigs -Usually 3 legs which stand on the seabed (bottom supported)

-Hull is lowered and legs are raised for rig moves

-It can drill in shallow waters (to 300-ft)

-BOP's are below the derrick cantilever

Semi-Submersible Rigs -Rig towed on to location, then either anchors or uses dynamic positioning

-Can relocate quickly if problems arise

-Usually uses BOP's located at the seabed.

Deepwater Offshore Rig - Drillship -Usually self-propelled for rig moves

-Often uses dynamic positioning

-Sometimes anchored

-Has high storage capacity

Offshore Rig Selection Many designs criteria are used in selecting the proper marine rig. Major criteria are as follows:

-Water depth rating (first evaluation tool)

-Derrick and substructure capacity

-Physical rig size and weight (MAINTENANCE HISTORY)

-Deck load capacity

-Stability in rough weather (wind)

-Rig horsepower, pipe handling and mud mixing capabilities

-Type of drilling: Exploratory versus development drilling

-Availability and rig cost.

Drilling Team Drilling Contractor:

-Tool pusher, drillers, derrickman, roughnecks

-Other specialists - crane operator, mechanics, electricians, roustabouts, caterer

Operator's Representatives:

-Company man, drilling engineers, geologists, and consultants

Service Companies

-Cementer, loggers (mud & wireline), mud engineer, directional engineer

Rotary Drilling Process -In rotary drilling, the bit is turned by rotating the entire drill string, using a rotary table at the surface

-The entire downward force is applied to the bit by using sections of heavy thick-walled pipe called drill collars, in the drill string above the bit.

Basic Rig Components All rotary rigs have the same basic drilling equipment, with the following major components or systems:

-Power system

-Hoisting system

-Fluid-circulating system

-Rotary system

-Well control system

-Well monitoring system

1. Rig Power System -Most rig power is consumed by the hoisting and fluid circulation systems. Fortunately, both systems are not used at the same time.

-Power requirements: 1,000 - 3,000 HP (horse power)

-Types of power prime movers: IC diesel engine & diesel-electric

-Performance is characterized by output HP, torque, and efficiency

Rig Power System: Input Power -Input power: The rate fuel energy input delivered to the power system:

-Power input = Fuel consumption rate * heating value = wf * DH

Rig Power System: Output Power Output power: The rate of shaft work provided by the rig power system to equipment and rig components:

Rotating Systems:

Power output = Torque * Angular Velocity

= T * w

Systems with Linear Motion:

Power output = Force * Velocity

= F * V

Rig Power System Efficiency The overall efficiency of the rig power system is the energy output per energy input:

Efficiency = Output power / Input power

2. Hoisting System -The hoisting system is designed to lower or raise the drillstring, casing string, and other subsurface equipment into or out of the hole.

-The principal components of the hoisting system are:

1. Derrick and substructure;

2. Block and tackle;

3. Drawworks.

Block and Tackle (BT) Block and tackle is comprised of:

-Crown block;

-Travelling block

-Drilling line (cable)

The function of block and tackle is to provide a mechanical advantage, which permits easier handling of large loads.

The mechanical advantage M of a block and tackle is simply the ratio of the load W and the tension force applied on the drawworks,

Fs: M = W/F_s

Ideal Mechanical Advantage Assumes no friction in the block and tackle

Can be determined from force analysis;

Force balance in the vertical direction yields:

nF_s=W

where n is the number of lines strung through the travelling block. Combining Eqns. (1) and (2), the ideal mechanical advantage is:

M_i= W/(W/n) = n

Input & Output Powers of the BT https://o.quizlet.com/9jr7SDNFTTJO8EmpWVbbrg_m.png

Tension on the Fast Line https://o.quizlet.com/RluydUsoxu0P5sL8FMCPfA_m.png

Strength of Drilling Line The drilling line is subjected to rather severe service during normal tripping operations.

Failure of the drilling line can result in:

-Injury to the drilling personnel;

-Damage to the rig; and

-Loss of the drillstring in the hole.

Therefore, it important to keep drilling line tension well below the nominal breaking strength and maintain the drilling line in good conditions.

Safety Factor (SF): SF = breaking strength/actual tension

Actual tension = Ff; Typical SF range (2 < SF < 4.0)

Breaking Strength of Wire Rope https://o.quizlet.com/Uwzet8KqYFlTi3ljf20HJQ_m.png

Total Derrick Load https://o.quizlet.com/A-.7ugxpgoBYdz9E0Qh-eA_m.png

Load on Each Derrick Leg https://o.quizlet.com/.BsSTTWucYuvxeFMFAp29A_m.png

Derrick Leg Load Formulas https://o.quizlet.com/9hHHuYIy-Jlw.UM6bq8AzQ_m.png

Derrick Efficiency Factor https://o.quizlet.com/K0V75CInhZrbo6R05ZbwLQ_m.png

Arrangement of Block and Tackle https://o.quizlet.com/nlwPTuO.FJcvvwK.Vvc5LA_m.png

Drawworks Provide the hoisting and braking power required to raise and lower the heavy strings of pipe

The principal parts of the drawworks are:

-Drum

-Brake (hydrodynamic or electromechanical type);

-Transmission (for direction control) ;and

-Catheads (spool used to tension the drilling line)

The drum transmit the torque required for hoisting and braking

It also stores the drilling line (cable) required to move the traveling block the length of the derrick.

3. Rig Fluid Circulating System One of its functions is to remove rock cuttings out of the hole as drilling progresses.

Principal components are

-Pumps

-Pits/tanks

-Mixing devices

-Contaminants removal equipment (solid control devices), and

-Flow conduits https://o.quizlet.com/HQE1Ps9Fp1zDE14RE.cp6g_m.png

Mud Circulation Path The drilling mud travels:

1. From steel suction tanks to the mud pump;

2. From the pump through the high-pressure surface connections to the drillstring;

3. Through the drillstring to the bit;

4. Through the nozzles of the bit and up the annular space between the drilling string and hole to the surface; and

5. Through the contaminant-removal equipment back to the suction tank

Mud Pumps https://o.quizlet.com/zek4yZmKcpOX5-qHGWPgvg_m.png

Mud Pumps (cont...) https://o.quizlet.com/CMHz-L9hOu2bWm4v4keh9Q_m.png

Surge Chamber & Relief Valve -The surge chamber greatly dampens the pressure surges developed by the positive displacement pump;

-Pump discharge line also contains a pressure relief valve to prevent line rupture in the event the pump is starts against a closed valve; https://o.quizlet.com/qDgQU6lT0PUYErw2fddf0w_m.png

Double-Acting Duplex Pump https://o.quizlet.com/92jl9Z4H3tGaQSaik6GwWA_m.png

Duplex and Triplex Pump Flow Rate https://o.quizlet.com/8x.dZzRpum30pKd0dty2SQ_m.png

Pump Horse Power https://o.quizlet.com/F0uG0jqnwonTG71yyEzN-g_m.png

Mud Pits or Mud Tanks Mud pits or tanks are often made of steel;

Three basic types of mud tanks: settling, suction, and reserve

1. Settling tank: allows time for setting of cuttings & release of entrained gas

2. Suction tank: the pump sucks good fluid from it

3. Reserve tank (surface pit): to contain contaminated fluid, cuttings, and any produced formation fluid. In the event some drilling fluid is lost to underground formations (lost circulation), the fluid in the reserve pit is used as make fluid.

All tanks are equipped with motor-driven agitators (mixers)

Flow Conduit Connecting the Mud Pump to the Drillstring The flow conduit connecting the mud pump to the drillstring include:

1. Surge chamber/pulsation dampener,

2. Heavy pipe: connects the pump to a manifold located on the rig floor;

3. Standpipe and rotary hose: provide a flexible connection that permits vertical and rotation movement of the drilling string;

4. Swivel; and

5. Kelly: allows the drillstring to be rotated. https://o.quizlet.com/geDn8GALdrJHPC96QkKgmw_m.png

Swivel Allows the flow of mud and pipe rotation simultaneously.

Contains roller bearings to support a rotating pressure seal that allows fluid through the swivel. https://o.quizlet.com/BjWblV1kVGnHryU6ijZVUw_m.png

Contaminants Removal Equipment -Shale shaker - a vibrating screen that removes coarse rock cuttings;

-Settling pit: additional separation of solids and gases from the mud occurs in the settling pit.

-Hydrocyclone/decanting centrifuge - removes fine particles;

-Mud cleaner - a combination of a hydrocyclone and a shaker screen, and use only for weighted mud;

-Degasser - removes entrained gas from the fluid

Hydrocyclone -A hydrocyclone is a cone-shaped housing that imparts a whirling fluid motion much like a tornado due to high velocity tangential fluid inlet;

-The heaver solids in the mud are thrown to the housing of the hydrocyclone and fall through the apex at the bottom; and

-Most of the liquid and lighter particles exit through the vortex finder at the top. https://o.quizlet.com/Smpq8ziWVLLkwoD3Gvo86g_m.png

Decanting Centrifuge -A decanting centrifuge is consists of a rotating cone-shaped drum which has a screw conveyor attached to its interior.

-The rotation of the cone creates a centrifugal force that throws the heaver particles to the outer housing.

-The screw conveyer moves the separated particles to the discharge. https://o.quizlet.com/rYh829iKc015GbKQG.cQxg_m.png

4. Rotary System Includes all the equipment used to achieve bit rotation;

Can be conventional or modern type;

Conventional rotary system is made up of

swivel,

kelly

kelly bushing,

rotary drive,

rotary table, and

the drillstring (i.e. drill pipe and drill

collars)

Modern rotary system is TOP DRIVE, also called power swivel https://o.quizlet.com/laPwCejLnyWJwAvKAuMjjQ_m.png

Components https://o.quizlet.com/ZRe5YBL9WTllfxz68khgLg_m.png

Kelly A long square or hexagonal steel bar with a hole drilled through the middle for a fluid path.

Is used to transmit rotary motion from the rotary table or kelly bushing to the drillstring, while allowing the drillstring to be lowered or raised during rotation.

The kelly goes through the kelly bushing, which is driven by the rotary table.

Kelly 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 transmits the rotary motion from the rotary table to the kelly

The kelly then turns the entire drillstring because it is screwed into the top of the drillstring itself.

Depth measurements are commonly referenced to the RKB, such as 8327 ft RKB, meaning 8327 feet below the kelly bushing.

Rotary Table The revolving or spinning section of the drill-floor that provides power to turn the drillstring.

Almost all rigs today have a rotary table, either as primary or backup system for rotating the drillstring.

Top-drive technology has replaced the rotary table in offshore and directional drilling applications.

Top Drive (Power Swivel) Regular swivel, kelly, and kelly bushing are entirely eliminated;

Has built-in tongs to make and breakout pipes;

Uses a hydraulic motor to achieve rotation;

Safer & easier for crew members to handle

the drill pipe;

Saves time as connections are made very fast and safer; and

The crew uses the unit's built-in tongs. https://o.quizlet.com/d3-Z31XQuZjYguY07q5yzA_m.png

Tubular Specifications All tubular (drill pipe, drill collar, casing, and tubing) are specified by the following:

Range (length): 3 ranges -

• R1 (18 - 22 ft, now obsolete),

• R2(27-30ft),

• R3 >30 ft]

Weight per foot

Outside diameter, OD

Steel grade (D, E, G, & S-135)

Tubular Specifications (cont..) https://o.quizlet.com/y3WDI0X3p2Fbv.wDy1VIqg_m.png

Capacity and Displacement Volumes https://o.quizlet.com/gdSfz.gZv.nuuV4k6HYgHg_m.png

Drill Pipes and Drill Collars Drill pipes

-Transmit rotational power to the bit

-Transmit drilling fluid to the bit

Drill collars

- Provide weight on bit

- Prevent buckling of the drill string

- Provide pendulum effects to cause the bit to

drill a more nearly vertical hole

- Support and stabilize the bit to drill new hole

aligned with the already drilled hole

Drill collars can be round (most), spiral, or square

-Spiral ones are used in small diameter holes or deviated wells to prevent or reduce differential pipe sticking

- Square used in straight hole (vertical) drilling

Drill Pipe https://o.quizlet.com/wxEavfWWE4O9KRpMXDY4PQ_m.png

Drill Collars https://o.quizlet.com/ypwvuzDg5nbQl4Kz2tNYUg_m.png

Drill Collar Connections Different from drill pipe connection

The weakest part of a collar

Note: drillpipe tool-joint is the strongest part of the pipe

When damaged, the connection is cut and the collar is re- threaded https://o.quizlet.com/OtKDcMuPFy-TmqK5NmKPRA_m.png

Crossovers https://o.quizlet.com/OCme0a.Gd7LU7OK2B7LxTA_m.png

Jar https://o.quizlet.com/Pq5K0oi5st8Mew2OT5309g_m.png

Stabilizers https://o.quizlet.com/rygznJsnUrvJs1SRuTYbiw_m.png