Mud circulation system:

Mud circulating system developed during the end of 1940s, after high pressure pumps and jet bits became available. Modern mud system is a combination of various systems all for the purpose of circulating mud and to clean it.

Mud Circulating System Components:

·        Mud return line

A trough or pipe, placed between the surface connections at the well bore and the shale shaker.

·        shale shaker

A series of trays with sieves or screens that vibrate to remove cuttings from circulating fluid; openings size are selected to match the size of the solids expected.

·        Desander

A centrifugal device for removing sand from; It may be operated mechanically or by a fast-moving stream of fluid inside a special cone-shaped vessel, in which case it is sometimes called a hydrocyclone.

·        Desilter

A centrifugal device, similar to a desander, used to remove very fine particles, or silt. To keeps the amount of solids in the fluid to the lowest possible level.

·        Degaser

The equipment used to remove unwanted gas from a liquid, especially from drilling fluid.

·        Mud-Gas Separator

A device that remove gas from the mud coming out of a well when a kick is being circulated out.

·        Mud Tanks (pits)

A series of open tanks usually made of steel plates, through which the drilling mud is cycled . Additives are mixed with the mud in the pit, and well . They are also called shaker pits, and suction pits, depending on their main purpose.

·        Mud Pumps

A large reciprocating pump used to circulate mud on a drilling rig.

·        Chock Manifold

The arrangement of piping and special valves, called chokes, through which drilling mud is circulated when the blowout preventers are closed to control the pressures encountered during a kick.

·        Mud gun

 Is typically used to mix the mud mixture in the rig tanks (see Figure).

This is done to maintain a homogenous mix and ensure an even distribution of mud components. In carrying out this function, the outlet pressure can become high enough that the gun might become unmanageable by workers.

  

Mud Circulating Systems:

Circulation of drilling mud begins from the mud pits, with suction lines leading to the mud pumps (figures). Mud pumps send the mud through the rotary hose into the swivel, down through the drill stem, and out through the bit. The mud returns to the surface through the annulus of the borehole, then through the mud return line back into the mud pits. The mud is made up and conditioned in the surface system, using various materials and auxiliary equipment.                                                        

The mud pump is the primary component of any system using a liquid as the circulating fluid. It furnishes the pressure for sending the fluid through the system. The swivel permits the drill stem to be raised or lowered while circulating and rotating. The drill stem, made up of Kelly, drill pipe, and drill collars, rotates the bit, furnishes weight for drilling, and provides the con dui through which fluid flows to the bit. Drilling fluid passes through the bit, out the nozzles, and up through the annulus, which is the space between the drill stem and the wall of the well. Fluid returning to the surface through the annulus carries with it the cuttings made by the bit. When the fluid reaches the surface, it flows into the mud pits through a mud return line, after having rock cuttings, sand, and shale separated from it by devices such as shale shakers, desanders, desilters, and centrifuges.

A system for pumping drilling mud typically operates at high pressure of up to 34,000 kilopascals (4,930 pounds/square inch). To ensure that a component of the system does not fail, all parts of the system must be rated at least equal to the maximum working pressure of the pump. This is also known as the “allowable rated working pressure”.

 Typically, this is shown on a metal plate affixed to the pump.