Oil Well Drilling mud pits

Mud pits are required for holding an excess volume of drilling mud at the surface. This surface

volume allows time for settling of the finer rock cuttings and for release of entrained gas

bubbles not mechanically separated. Also, in case some drilling fluid is lost to underground

formations, this fluid loss is replaced by mud from the surface pits. The settling and suction pits

sometimes are dug in the earth with a bulldozer but more commonly are made of steel. Mud pit

compartments are also called shaker pits, settling pits, and suction pits, depending on their main

purpose.. A large earthen reserve pit is provided for contaminated or discarded drilling fluid and

for rock cuttings. This pit also used to contain any formation fluids produced during drilling and

well testing operations. mud pit usually lined with a single-ply 20 or 30 milmeter polyethylene

.liners that resist punctures and wind damage to prevent any contamination

Dry mud additives often are stored in sacks, which are added manually to the suction pit using

mud mixing hoppers. However, on many modern rigs bulk storage is used and mud mixing is

largely automated. Liquid additives can be added to the suction pit from chemical tank. Mud

.jets or motor-driven agitators often are mounted on the pit for auxiliary mixing

This equipment includes mechanical devices for removing solids and gases from mud. The

coarse rock cuttings and cavings are removed by the shale shakers, the shale shaker is

composed of one or more vibrating screens over which mud passes as it returns from the hole

The risk in shale shakers is that gas may be present in vicinity of shale shaker leading to a a

.probable explosion or toxicity

Multiple shakers may be used

In parallel for high flow rate -

In series for multiple filtering range -

When the amount of finely ground solids becomes too great, they can be removed by

hydrocyclone and decanting centrifuges also called (desander). A hydrocyclone is a cone-

shaped housing that imparts a whirling fluid motion much like a tornado. The heavier solids in

the mud are thrown to the housing of the hydrocyclone and fall through the apex at the bottom

.Most of the liquis and lighter particles exit through the vortex finder at the top

The decanting centrifuge (desilter) consists of rotating cone-shaped drum which has a screw

conveyor attached to its interior . rotation of the cone creates a centrifugal force that throws the

heavier particles to the outer housing. The screw conveyor moves the separated particles to the

discharge

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