Drilling rig components are the mechanical, electrical, hydraulic, and well-control equipment used to drill, re-enter, and work over wells. The main systems include hoisting and rotation, power generation, mud circulation, and well control. This illustrated glossary identifies the principal rig equipment, explains each component’s function, and provides diagrams and a downloadable reference PDF.
- DRILLING
- RE-DRILL OR RE-ENTRIES
- WORKOVERS
Drilling Rig Components: Quick Reference
What are the main components of a drilling rig? The equipment falls into four principal operating systems. The table below summarizes their purpose and representative components; pipe-handling and solids-control equipment support these systems throughout the operation.
| Rig system | Typical components | Main function |
|---|---|---|
| Hoisting and rotation | Derrick or mast, drawworks, crown block, traveling block, drilling line, top drive or rotary table | Lift, lower, suspend, and rotate the drill string. |
| Power generation and distribution | Engine-generator sets, switchgear, transformers, motor controls, and drives | Supply and regulate power for rig equipment. |
| Mud circulation | Mud pumps, standpipe manifold, mud tanks, mixing equipment, and solids-control units | Circulate and condition drilling fluid to clean and support the wellbore. |
| Well control | BOP stack, accumulator, choke and kill lines, choke manifold, and inside BOP | Provide pressure-control barriers and manage well flow during well-control operations. |
Drilling Rig Equipment Systems Components
Four main systems support drilling operations. Together, they handle hoisting and rotation, generate power, circulate drilling fluid, and control well pressure:
- HOISTING & ROTATION SYSTEM
- POWER GENERATION SYSTEM
- MUD CIRCULATING SYSTEM
- WELL CONTROL SYSTEM
HOISTING & ROTATION SYSTEM COMPONENTS IN DRILLING RIGS
- MAST & SUBSTRUCTURE
- CROWN BLOCK
- TRAVELING BLOCK
- TOP DRIVE
- ROTARY TABLE
- DRAWWORKS
- DRILLING LINE
- DEADLINE ANCHOR
POWER GENERATION SYSTEM
Ac-Dc Power Generation Station Example:
- GENERATORS
- CONTROL PANELS
- TRANSFORMER
- DC MOTOR
- DIGITAL DRILLER CONSOLE
- MOTOR CONTROL CENTER
MUD CIRCULATING SYSTEM COMPONENTS IN DRILLING RIGS
- MUD PITS
- MUD MIXING HOPPER
- MUD PUMPS (HI AND LOW PRESSURE)
- SHAKERS
WELL CONTROL SYSTEM
- RIG FLOOR MUD MANIFOLD
- INSIDE BOP
- BOP STACK
- CHOKE & KILL LINES
- CHOKE & KILL MANIFOLD
- BOP ACCUMULATOR
- BOP CONTROL MANIFOLD
Drilling Rig Components
Derricks
Drilling derricks and Rig Masts consist of a steel framework with a square or rectangular cross-section. Their purpose is to support the hoisting equipment and rack the tubulars while tripping pipe.
The derrick height determines whether the rig can handle single, double, or triple stands of pipe.
Drawworks
The Drawworks is one of the most important components of the drilling rig (types of drilling rigs). The drawworks provides hoisting power and spools the drilling line while the drill pipe is run into and pulled out from the well. During lowering, the drawworks pays out the drilling line. During hoisting, its drive system reels the line back onto the drum.
Crown Block
The Crown Block as a drilling rig component is a fixed set of pulleys (called sheaves) located at the top of the derrick or mast, where the drilling line is threaded. The companion blocks to these pulleys are the traveling blocks. By using two sets of blocks in this fashion, great mechanical advantage is gained, enabling the use of a relatively small drilling line to hoist loads many times heavier than the cable could support as a single strand.
Traveling Block
The Traveling Block is a set of sheaves (pulleys) that move up and down in the derrick. The rig crew reeves the drilling line through the crown-block and traveling-block sheaves. This provides a great mechanical advantage to the drilling line, enabling it to lift heavy loads of pipe and casing. The number of sheaves and lines strung determines the hoisting system’s mechanical advantage and load capacity.
Hook
The hook hangs below the traveling block. It supports the swivel and rig kelly (for drilling) and the elevator bales (for tripping pipe and casing).
Drilling Line
When selecting a drilling line, consider these mechanical and service requirements:
- Diameter
- Breaking strength
- Flexibility
- Elasticity
- Corrosion strength
- Abrasion resistance
- Distortion strength
Drilling line selection and maintenance should follow the applicable wire-rope specifications and operating guidance, including API Spec 9A and API RP 9B where required by the rig program.
Rotary Table
On conventional kelly-drive rigs, the rotary table performs two main functions. By comparison, a top drive system rotates the drill string from above:
- Transmit rotation to the BHA through the Kelly Bushing.
- Provide a location for the slips and supporting equipment used to suspend the drill string when required.
On rigs equipped with a top drive, the rotary table primarily supports tubular loads through the slips. The top drive supplies drill-string rotation.
Kelly & Drive Bushing
The kelly transmits rotary-table torque through the drill string to the bottomhole assembly.
Types:
Manufacturers supply kellys with either square or hexagonal cross-sections.
- Hexagonal kelly
- Square kellY
Kelly Valves
Kelly valves are drill-stem safety valves fitted above or below the kelly on conventional kelly-drive rigs. The upper and lower kelly cocks provide a means to isolate flow through the drill string during well-control events (see kick warning signs). Conventional manual valves require the correct operating wrench and access to the valve. Depending on its configuration, a top drive may use remote-operated inside BOP (IBOP) valves, manually operated valves, or both. The crew must follow the installed equipment’s operating and well-control procedures.
Swivel Head
The Swivel head has 3 main functions:
- Bears the drill string load
- Enables string and bottom hole assembly rotation
- Allows circulation
Top Drive
Conventional rotary rigs use a rotary table and kelly to turn the drill string. In contrast, a top drive rotates the string from the traveling assembly and can drill with stands of pipe. Modern drilling rigs commonly use top drives, which perform three key functions:
- Perform all normal hoisting requirements
- Rotate the drill string
- Enable circulation through the drill string
Today, many drilling rigs use a top drive instead of a conventional kelly drive.
Advantages:
- Possibility to drill stands of drill pipe rather than single
- Ability to back-ream while pooh
- Contains remote-controlled Inside BOP, that can be operated at distance from the rig floor
Manufacture specifications
- For applicable hoisting equipment, consult API Spec 8C (Drilling and Production Hoisting Equipment) and the top-drive manufacturer’s specifications. Verify which components fall within the standard’s scope.
- ISO 13535 addresses drilling and production hoisting equipment. Check the applicable edition and equipment scope rather than assuming every top-drive component is covered.
Read more on Top Drive in Drilling Components, Pros & Maintenance Steps
Drilling Rig Floor Mud Manifold Equipment
The rig-floor mud manifold consists of high-pressure piping and valves. It connects the mud pumps to the injection head in order to circulate the drilling mud down the DP. There are several outlets on the mud manifold to connect the pressure transducer. This allows the crew to monitor the “stand pipe pressure“
Types:
- Single Stand Pipe
- Dual Stand Pipe
Mud Pumps
Two common types of reciprocating high-pressure mud pumps are duplex and triplex pumps:
- A conventional duplex mud pump has two double-acting pistons. During each stroke, one side of each piston discharges fluid while the opposite side draws fluid into its chamber.
- A conventional triplex mud pump has three single-acting pistons or plungers. Each fluid end discharges on its pressure stroke and fills on the return stroke. Triplex pumps are widely used on modern drilling rigs because they provide high-pressure output in a comparatively compact arrangement; actual flow smoothness depends on pump design and pulsation-dampening equipment.
An electric motor or diesel engine drives the crankshaft, which moves the pump pistons.
A reciprocating mud pump has two principal assemblies:
- POWER END
- FLUID END
Read more on Mud Pump In Oilfield Rigs Parts, Types & Calculations
Mud Mixing System:
The mud mixing system performs two essential tasks:
- Prepare and mix the mud.
- Maintain mud weight (check also Mud balance test procedure) and mud properties while drilling the well.
Select the mixing and circulation rates according to the mud-system design, equipment limits, and approved mixing procedure. Maintain enough agitation to keep weighting agents such as barite and other solids suspended, and add bentonite or polymers at the recommended rate to prevent poor dispersion and clumping.
NOTE: event of a kick: The mud mixing system must enable personnel to mix as much mud as required, as fast as possible, in the event of a kick (check also kick tolerance – Kick sheet calculations).
The mud mixing system includes:
- Centrifugal pumps
- Funnel with nozzle and Venturi pipe
- Charging hopper
Mud Pits
Mud pits allow the rig crew to:
- Store and circulate drilling fluid within the rig’s active mud system
- Monitor the physical and rheological characteristics of the mud
- Monitor pit-volume changes that may indicate lost circulation or an influx; lost-circulation materials may be prepared and added through the mud system when directed by the drilling program
- Support kick detection and volume monitoring during well-control circulation, including the Wait and Weight method and Driller’s Method; the mud pits do not themselves control a kick
- Provide the active and reserve mud capacity specified by the drilling program
Mud pit capacity depends on several operating and regulatory factors:
- Formations and characteristics
- Applicable laws at the operation zones
- Well’s depth
- Logistic positioning and well site.
Rig mud pits generally fall into two categories:
- Active Mud Pit System
- Supply Mud Pit System
Trip Tank Component In Drilling Rigs
For monitoring of the mud – It is necessary to monitor the amount of mud that exits or enters the hole as the drilling string is run in or out. The monitoring, or measurement, can be done either by using the rig pumps and calculating the number of strokes required to fill the hole or by using a trip tank.
A trip tank is a calibrated tank used to measure small changes in drilling-fluid volume accurately during tripping. Its measurement resolution and accuracy must satisfy the rig’s approved well-control procedures and applicable operating requirements; a universal ±1 bbl tolerance should not be assumed. As the crew pulls pipe out of the hole, the tank helps track the fluid required to keep the hole full and compare actual fill volumes against calculated displacement.
The mud fills the hole by a pump with a return line from the bell nipple to the tank. A continuous fill up device doesn’t require as much of the driller’s attention.
Components
Trip tank used on every rig has:
- pit
- centrifugal pump
- pit level.
Solids Removal Equipment in Drilling Rig
A large number of solids in the mud can cause many problems during drilling. It also results in
high mud treatment costs trying to maintain the shape of the mud. The purpose of solid removal equipment is to contain the percentage of solids in the mud at an acceptable level.
The benefits of a low solids content are:
- Higher rate of penetration during drilling (check: Drilling Parameters Optimization In Oil & Gas Guide)
- Increased bit life (Learn more about: Bit dull grading)
- Reduced mud control costs
- Reduced mud pump maintenance costs
- Reduced possibility of stuck pipe
- More regular hole geometry
- Reduced need for mud dilution
- Increased cement efficiency
- Reduced BHA torque (check also drilling torque and drag)
- Solids control equipment
Solids control equipment as a component used on a Drilling Rigs include:
- SHALE SHAKER
- DESANDER & DESILTER
- MUD CLEANER
- DECANTER CENTRIFUGE
Degasser
The purpose of degassers is to remove air or gas entrained in the mud system in order to ensure that the proper density mud is recirculated down the drill pipe. If the gas or air is not removed, the mud weight measured in the pits may be misleading. This will result in the addition of unnecessary amounts of weight material thereby giving true mud densities down the hole that are more than desired. Gas contamination could result from:
- Drilling Gas.
- Trip Gas.
- Connection Gas.
- Well testing.
Degassers remove entrained gas from drilling fluid, but they do not all use the same mechanism. Vacuum degassers lower the pressure over the fluid to promote gas release; atmospheric or mechanical designs rely on agitation, spreading the fluid into thin films, and gas separation without necessarily applying a vacuum.
- VACUUM DEGASSER: A vacuum system lowers the pressure inside the degassing vessel. Gas leaves the drilling fluid and flows to an appropriate discharge or handling system.
- ATMOSPHERIC OR MECHANICAL DEGASSER: Internal baffles, spray arrangements, or mechanical agitation expose more fluid surface area and help entrained gas separate. The gas must be routed or vented according to the equipment design and site safety requirements.
Drill Pipe Component in Drilling Rigs
A joint of drill pipe consists of two main parts: the pipe body and the tool joints.
- Pipe body: consult API Spec 5DP (Drill Pipe) for applicable drill-pipe requirements; API 5D is an older reference.
- Tool joints: the box and pin connections are attached to the pipe body. Consult API Spec 5DP for drill-pipe assembly requirements and API Spec 7-2 for applicable rotary-shouldered connection threading and gauging.
ISO 11961 addresses steel drill pipe for petroleum and natural gas industries. Consult the applicable published edition and project requirements.
Read more on Drill Pipe API Specifications
Heavy Weight Drill Pipe
As a component of the Drilling rig String, Heavy weight Drill pipe has a unit weight between Drill Pipe and Drill Collars. They are run between Drill Collars and Drill Pipes to:
- Create a gradual reduction of BHA rigidity (check BHA types) between the two.
- Reduce fatigue stress on the DP just above the DCs.
- Provide an intermediate stiffness and weight section that helps manage bending stresses and drill-string dynamics when properly designed.
Heavy-weight drill pipe specifications depend on the product design and manufacturer. Consult the applicable requirements of API Spec 7-1 for rotary drill-stem elements, together with the manufacturer’s dimensional and inspection documentation; do not treat ISO 10407 as a universal HWDP dimensional specification.
Benefits:
- HWDP can often be racked back in stands, which may reduce handling time compared with some drill-collar arrangements
- HWs stand back in the rack like regular Drill Pipe
- In directional wells, HWDP placement can influence torque, drag, bending stresses, and BHA behavior. Its effect must be evaluated for the specific well trajectory and drill-string design.
Drill Collars
Drill collars are the components of the drill string (check also Drill string Design Calculations) that provide the weight on the bit when drilling (drill string weight calculations). They are thick-walled, hollow tubular machined from solid bars of steel (usually plain carbon) or non-magnetic nickel-copper alloy or other non-magnetic premium alloys. The outside diameter may be machined with helical grooves (spiral) to reduce the potential contact surface for differential sticking prevention.
For drill-collar dimensional and product requirements, consult API Spec 7-1 (Rotary Drill Stem Elements) and the manufacturer’s current specifications. ISO 10407 relates to inspection and classification of used drill-stem elements, rather than being a draft dimensional specification.
DRILL COLLAR TYPES
- Smooth
- Spiral
Pipe Handling Tools
Elevator Links
The elevator links provide the connection between the hook (or Top drive) and the elevator.
There are 3 different types of links:
- Perfection Link
- Weldless Link
- Tool Pusher Link
Manual Slips
Manual slips must match the specified bowl taper, pipe size, load rating, and manufacturer’s instructions. Consult API Spec 7K for applicable drilling and well-servicing equipment requirements; do not assume one taper dimension applies to every slip assembly.
- Manual Slips for Drill Pipe
- Manual Slips for Drill Collars
- Manual Slips For Casing
- Manual Slips for Conductor Pipe
- Safety Clamp
- Automatic slips mechanically released
- Remote controlled Automatic slips
Elevators
- ELEVATORS for DP – DC Manual: These elevators have replaceable bushings to fit different sizes of pipe.
- Drill-collar lifting sub: Select an approved lifting sub and compatible elevator where required by the collar profile, lifting arrangement, and manufacturer’s instructions. Inspect the lifting shoulder and contact surfaces, confirm the load rating, and never assume an elevator can safely support a collar solely because it fits its diameter.
- Remotely controlled elevators for drill pipe or suitable drill-collar lifting assemblies, subject to the equipment ratings
- ELEVATORS for Casing: Special elevators are used for running casing procedures.
- Side Door Elevators: These are used for lightweights or for the first joints of csg.
- Slip type elevator:
- Slip type: Operated manually or by remote control, these can be used as elevators or clamps.
- Ton Elevator: Ton Elevator / Spide Varco Type: Size range from 2 3/ 8″ up to 24 ” for 200 ton to 1000 ton
- SINGLE JOINT ELEVATORS
Tongs
DP and DC make-up occurs in two stages:
- Spin the two tool joints together (spinning)
- Torque connection to tighten it (Make-up torque) Viceversa for Breakdown operations.
Use the approved make-up torque for the specific drill-pipe or drill-collar connection, based on manufacturer data and applicable drill-stem guidance such as API RP 7G. In a conventional tong arrangement, one tong applies torque while the other provides backup.
Spinning chain
Spinning was historically done with the spinning chain, but this was dangerous and the safety of all on the drill floor depended on the skill and experience of the man throwing the chain.
Spinning wrench
The automatic spinning wrench is now replacing the spinning chain in many drilling rigs.
TONGS for DP – DC & CASING Manual
Operational Two tongs are used and positioned on the 2 tool joints. The top one is for the torque and the bottom one is a backup tong.
Torque is applied by pulling the top tong with the cathead. For high torques a hydraulic piston is used for pulling (Ezy Torque).
- Torque applied: Torque applied is the result of the pull multiplied by the tong arm length.
- Torque Indicator: The pull should be applied as perpendicularly as possible to the arm to avoid false values.
TONGS for DP – DC & CASING Automatic
DP torque Wrench: Making up and breaking out made simple. The hydraulically powered TW-60 makes up and breaks out drill pipe tool joints and drill collars from 4 to 8 inch OD. Torque is adjustable and can be pre-set to the required value.
SPINNING & TORQUE Combination Wrench
- Tongs for DP – DC Automatic
- Tongs for CSG Automatic
PIPE RACK
The pipe rack is the place where tubular are stored and positioned before lifting them up the rig floor. In the photo shows Casings already equipped with centralizers all ready to be run in the well.
FINGERBOARD
The Fingerboard is one of the drilling rig components that is used to rack the tubular while tripping.
PICK UP & LAY DOWN MACHINE
A pickup-and-laydown machine transfers drill pipe, casing, and other tubulars between the pipe rack and the rig floor. It reduces manual handling and helps control tubular movement; the crew must remain within the equipment’s rated load, size range, and approved operating procedures.
CSG STABBING BOARD
Casing Stabbing Board is a personnel mobile platform (platform rig) used for CSG operations. It’s installed in the derrick. It can be moved up and down to enable the operator to guide the Csg joint from the topside. Its equipped with several anti-fall devices.
DIVERTER
A diverter is typically installed during shallow-hole drilling when a conventional pressure-rated BOP arrangement may not yet be in place. Its purpose is to direct shallow gas or fluid flows away from the rig through appropriately designed vent lines. A diverter is not intended to shut in or contain well pressure like a pressure-rated BOP. The crew must follow the approved diverter procedure, including the required flow path and operating sequence.
- Diverter equipment and controls must meet the applicable project requirements and manufacturer specifications. Review API Spec 16D for diverter control systems, API Spec 16A for applicable drill-through equipment, and the rig-specific diverter procedures; their scopes are different.
DRILLING RIG ANNULAR PREVENTER COMPONENT
The annular preventer is part of the BOP STACK (check also BOP tests and acceptance procedure) installed on the wellhead once the anchor casing is run and cemented in the hole (Casing Cementing).
The BOP is the second and final safety device to handle the uncontrolled flow of formation fluids (hydrostatic mud pressure is the first) from well. The annular BOP is engineered to close tightly on any cylindrical body with dimensions as large as the maximum opening ID of the BOP to dimensions as small as the fully closed position.
The annular BOP can close on Drill Pipes, Drill Collars, Casing, Tubing, Tool joints the kelly, and wireline. It is not requested, as with the Ram BOP, to check the position of the Tool Joint before closing.
RAM PREVENTER
The BOP is the second barrier to stopping the uncontrolled formation of fluids from coming into the well. The BOP is only used when the first barrier (hydrostatic mud pressure) has failed. In addition to the bag preventer, a number of rams are used.
The number and type of rams in the BOP stack depends on:
- Maximum pressure that is expected in the well.
- BHA dimensions (OD).
BOPs are designed to enable the crew to change the size and type of rams easily. The types of rams in use include:
- Pipe Rams
- Variable Rams
- Blind Rams
- Blind / Shear Rams
API Spec 16A covers applicable drill-through equipment, including ram-type blowout preventers. Confirm the relevant product specification, pressure rating, and manufacturer documentation for the installed BOP.
Drilling Rig BOP Control System Components
BOP Accumulators produce and store hydraulic energy to be used when BOP must be closed rapidly
because of emergency conditions. It’s equipped with the necessary controls to actuate BOP’s and
hydraulic valves during drilling and in case of a well blowout. BOP control system must provide :
- A minimum pre-determined pressurized volume to operate all BOP functions in an emergency situation.
- Reasonable accumulator recharge time.
The Accumulators are composed by:
- a tank containing hydraulic fluid (oil) at atmospheric pressure;
- one or more high-pressure pumping units to pressure fluid;
- nitrogen precharged bottle to store pressurized fluid.
The control system routes high-pressure hydraulic fluid through a manifold and then to the BOP closing mechanisms via
provided control valves.
- API Spec 16D covers applicable BOP control-system equipment. API Standard 53 addresses blowout-prevention equipment systems and operational requirements; it is not a substitute for the control-system product specification.
Inside BOP
There are several components of the drilling rig in addition to the primary blowout prevention equipment
that is sometimes necessary to control a kick. The equipment which furnishes closure inside the drill string is called an “INSIDE BLOWOUT PREVENTER”.
They are installed on the top or inside the Bottom Hole Assembly with the purpose to provide a means of closing the string for well control or even to permit repair/replace some tools.
- For inside BOPs and drill-stem valves, consult API Spec 7V (Drill Stem Valves) and the manufacturer’s requirements. API Spec 7-2 applies to relevant rotary-shouldered connection threading and gauging; API Spec 6A is not the general manufacturing standard for inside BOPs.
Kill & Choke Lines And Valves
The high-pressure mud circuit is the surface circuit connected to the wellhead; it is used to circulate with the well shut (driller’s method – wait and weight method) and when high-pressure ratings are recorded. Its main components are high-pressure lines and valves through which the mud flows in and out of the well during blowout control.
The high-pressure circuit has an extremely important function and therefore all parts must be regularly checked and maintained to ensure full efficiency and functionality.
The high-pressure circuit includes:
- kill lines
- choke lines
- choke manifold
- flare lines
- high-pressure valves
- adjustable chokes
Choke Manifold Component in Drilling Rig
Closing the BOP isolates the well at the surface, while the choke manifold provides a controlled flow path for selected well-control circulation and pressure-management operations. Adjustable drilling chokes regulate flow and backpressure. The number, type, arrangement, and redundancy of chokes must follow the applicable well-control design requirements and approved rig configuration; do not assume one fixed choke count is suitable for every installation.
Drilling Choke Control Panel
The function of the remote hydraulic choke control system is to provide reliable control of the drilling choke from one or more remote locations with the sensitivity and resolution required to perform all well control procedures which the choke valve is designed to provide, including:
- well flow shut-in procedures.
- throttling of mud, gas, liquid hydrocarbons, and formation debris at any rate of flow up to the physical capacity of the internal flow conduit.
Mud Gas Separator
The mud gas separator removes free gas from gas-cut drilling fluid. It then directs the separated gas through a dedicated vent line to a designated safe discharge location.
- Select, install, inspect, and operate the mud-gas separator according to the approved well-control program, manufacturer’s specifications, and applicable API Standard 53 requirements. API Standard 53 should not be described as a mud-gas-separator manufacturing specification.
Download Drilling Rig Components PDF
Frequently Asked Questions About Drilling Rig Components
What is the difference between a top drive and a rotary table?
A top drive rotates the drill string from an overhead motor assembly and can drill with stands of pipe. A conventional rotary table transmits torque through the kelly and kelly bushing. On top-drive rigs, the rotary table may still serve as a location for slips to support the string.
What is the purpose of a trip tank on a drilling rig?
A trip tank measures comparatively small drilling-fluid volume changes while tubulars move into or out of the well. The crew compares measured fill or displacement volumes with calculated values to help identify possible influxes or losses. The tank must meet the accuracy and calibration requirements of the rig’s approved procedures.
What is the difference between a degasser and a mud-gas separator?
A degasser removes entrained gas from the circulating mud system so that the fluid can be conditioned for reuse. A mud-gas separator, often used during well-control circulation, separates larger volumes of free gas from returning well fluids and directs the gas to a designated safe discharge location. These devices have different duties and operating limits.
Does a diverter replace a blowout preventer?
No. A diverter routes shallow flows away from the rig; it is not a pressure-containing substitute for a rated BOP. The required configuration depends on the well design, drilling phase, and approved well-control program.
Drilling Rig Equipment Standards and Further Reading
For equipment specifications and safe operating practices, consult the applicable manufacturer manuals and current standards. The American Petroleum Institute (API) publishes standards for drilling and well-control equipment. In addition, the International Association of Drilling Contractors (IADC) provides industry resources on drilling operations and rig safety. Always verify the current edition and scope of each standard before applying it to a particular rig.
For an ongoing thesis / project study.