Drilling Rig Systems

Drilling rig consists of following systems.

  • Hoisting system
  • Rotary system
  • Circulation System
  • Power system
  • BOP system
  • Monitoring system

Drilling Rig Hoisting System

It enable drilling rig to raise and lower working string into and out of well bore. main components of drilling rig hoisting system are: draw works, drilling line, crown block, traveling block, mast,dead line anchors and storage spool.

Draw works

It have a drum on which drilling line is reel in  and out to move travelling block inside mast or derrick for raising and lowering drilling string. 

draw works

How Drilling rig Systems Work-Complete Guide


Crown Block 

Crown block is top most part of mast or derrick. It have number of sheaves on it. The sheaves allow passage of drilling lines drawworks to travelling block. 


Drilling Line 

Drilling line is steel line, it is  drilling line that when reel in and reel out from  drawworks drum its move up and move down travelling block respectively. So its provide a mean to drawworks power source to perform tripping operation. 

Travelling Block 

Travelling block have a number of sheaves on it.It hangs TDS or kelly swivel with help of hook.Sheaves provide path for passing drilling line.   

Dead line anchor 

Dead line anchor fixed firmly dead line (drilling line between crown block and deadline anchor)  with the help of clamp nut and blots.  

Storage Spool 

Drilling line storage spool provide extra drilling line storage.When work done by drilling line (Ton-mile)  reach to recommended limit, fresh drilling line is added into system by loosening deadline anchor while slip and cut of drilling line operation.

Drilling Rig Rotary System 

Rotary system is responsible for rotating drill string. Drilling rig may have either TDS (Top drive system) or Kelly-swivel to transmit rotation to drill string. Rotary system components are TDS or kelly and drill string. The parts of drill string are drill pipe, heavy weight drill pipe, stabilizer,drill collar, x/o, bit sub and bit. 

TDS Vs Kelly Swivel

Top drive rotate drill string from top  where as kelly system rotation is provided at rig floor with help of rotary table.Top drive capable to drill with one stand of drill pipe and kelly can drill with one drill pipe. Therefore kelly system is time consuming as compared to TDS. Most of new rig coming with Top drive but still kelly system exist in drilling industry.

Drill string components

Drill Pipe 

Drill pipe are hollow steel pipe that make major part of drill string . It have pipe  body,threaded pin and box tool joint to make up drill pipes together. A drill pipe length is normally 30 ft. 

Heavy weight drill pipe

As the name indicates heavy weight drill pipe are heavier than same size of drill pipe. Heavy weight drill pipes are  part of BHA and are located between drill collar and drill pipe to work as transition zone.  

Drill collar 

Drill collars are most heaviest part of drill string and are also part of  bottom hole assembly. Drill collar have thick steel wall and less inside diameter  as compared to heavy weight drill pipe and drill pipe. Drill collar provide weight to bit  for drilling action. 


stabilizer provide weight and mainly control hole deviation. There are  two main types of stabilizers. 

Near Bit Stabilizer 

It is used just above bit, it have float valve inside it and have  box x box connection on both ends. 

String stabilizer

It is used between two drill collar and is located 30 or 60 ft  away from bit. it have pin x box connection. 

Cross over 

are drill string components used to connect two tubular of different threads. Cross over  can be of pin x box, pin x pin or box x  box connection. 


Drill bit is bottom most part of drill string, it drill formation or rock when apply rotation and weight on bit with circulation. 

Bits are classified as 


How Oil And Gas Well Is Drilled Step By Step Guide

Circulation System 

The circulating system is used to circulate drilling fluid down through the drill string and up the annulus, carrying out the drilled cuttings from the face of the bit to surface. Parts of circulation system are: suction tank, suction line, mud pump, mud pump discharge line. stand pipe, rotary hose, TDS swivel/kelly swivel,drill string, annulus, return line, solid control equipment.


Suction tank

It is mud tank from where mud pump suck the mud, after mud go through drill string, annulus and come to surface with return line,it is same tank where mud will come back after passing through solid control equipment. 

Suction line 

it ia located between mud pump and suction tank. With help of suction line mud pump suck fluid from suction tank. 

Mud Pump

Mud pump provide necessary hydraulic horse power to circulate mud through circulation system. Mud pumps are high pressure and high flow rate equipment to meet well drilling operation requirements. 

Discharge Line 

Mud pump after sucking fluid from suction tank it deliver fluid to discharge line. 

Stand pipe

Stand pipe receive drilling fluid from discharge line and give away to rotary hose. 

Rotary Hose

It is flexible  high pressure hose that transmit fluid to swivel connected with kelly or TDS. 


Swivel have dual function, it transmit fluid from rotary hose to drill string meanwhile it rotate also. As drill string rotate while drilling operation, we need some thing that is compatible with rotary motion of drill string and static condition of rotary hose. So swivel part connected to kelly or TDS it rotate whereas swivel part connected with rotary hose remain stationary. 

Drill string

Drilling fluid or mud from swivel pass to drill string and it  exits from bit. 


Annulus is space between tubular and open hole or cased hole. 

Ruturn Line

Return libe  take mud coming from wellbore to shale shaker. Where drilled cutting is removed.  

Solid Control Equipment

These are piece of euipment that remove cutting from mud. These are installed on mud tanks in sequence as Shale shake, Desander, Desilter, Centrifuge.

Shale shaker

When mud come wellbore to surface, the shale shaker are first defence line for solid control. The shale shaker have screens that are vibrated with the help of electric  vibrator. The drilled cutting and coarse particle are discarded to waste pit,where as mud with fine solid particle flow through shale shaker screen. 


Desander remove sand particles with the help of centrifugal force. It is located on down stream of shale shaker. It discard sand particles and any other solid particles that are same size as of sand. It consists two or three hydrocyclone cone. 

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it is located after Desander on mud tank. It remove silt and fine particles. It work same like desander but hydrocyclone cones installed on Desilter can be eight to twenty and are smaller in size. 


Mud Cleaner 

Mud cleaner is combination of Desander, Desilter and shale shaker. The under flow from Desander and Desliter is given to shale shaker. Underneath shale shaker fine screen recover  liquid phase of mud and weighting material like barite whereas it discard unwanted solid particles. Mud cleaner is used for weighted mud which use barite as weighing material.



It is located on down stream of desilter. It removes ultra fine particles. It also work on centrifugal force principle contrary to Desander and Desilter it have moving parts that are bowl and conveyor. The bowl drum is rotated at fast speed where as conveyor rotate at slower RPM but opposite to bowl drum. Because of fast movement of bowl drum the feed mud stream solid particle are thrown on inner wall of bowl due to high gravity force and are scraped out with conveyor and are discarded. where as clean mud is discharge to active tank.  

Power System

Rotary drilling rig power system is of prime importance as it will provide power to all other systems of rotary drilling rig, like hoisting system, rotary system, circulation system, BOP system and Monitoring system 

Watch following video to learn more about Drilling rig Power System. 


Blow Out Prevention System

What is Blow Out
A blowout is the uncontrolled release of crude oil and/or natural gas from an oil well or gas well after pressure control systems have failed

What is Blow Out Preventor (BOP)
BOP is an assembly of specialized valves or similar mechanical devices installed, during drilling, between the wellhead system and the drill floor. It is used to seal, control and monitor the well in case of kick

BOP system Components


BOP system Consists of:

vBOP control panels
vAnnular BOP
vPipe Ram
vVariable Bore ram
vBlind Ram/Shear Ram BOP
vMud cross (Drilling spool)
vKill line
vChoke line
vChoke manifold
vChoke control panel
vMud gas separator (Poor Boy) 

Monitoring System

Drilling rig motoring systems consists of various sensors located on mud tanks for monitoring mud levels and  on stand pipe for monitoring pressure, on TDS and rotary table for giving record of RPM and torque. Sensor located on Dead line anchor provide information for hook load, whereas sensor located on Drawworks s=drive shaft provide information for traveling block height. 

All these sensor provide their in put to Central control unit, which process input and display information in graphical and digital form on display screen. 

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