Mud pump

A mud pump is a reciprocating piston/plunger device designed to circulate drilling fluid under high pressure (up to 7,500 psi (52,000 kPa) ) down the drill string and back up the annulus.

A mud pump is a large reciprocating pump used to circulate the mud (drilling fluid) on a drilling rig. It is an important part of the oil well drilling equipment.

Mud pumps can be divided into single-acting pump and double-acting pump according to the completion times of the suction and drainage acting in one cycle of the piston's reciprocating motion.

Mud pumps come in a variety of sizes and configurations but for the typical petroleum drilling rig, the triplex (three piston/plunger) mud pump is the pump of choice. Duplex mud pumps (two piston/plungers) have generally been replaced by the triplex pump, but are still common in developing countries. Two later developments are the hex pump with six vertical pistons/plungers, and various quintuplex's with five horizontal piston/plungers. The advantages that these new pumps have over convention triplex pumps is a lower mud noise which assists with better Measurement while drilling (MWD) and Logging while drilling (LWD) decoding.

The "normal" mud pump consists of two main sub-assemblies, the fluid end and the power end.

The fluid end produces the pumping process with valves, pistons, and liners. Because these components are high-wear items, modern pumps are designed to allow quick replacement of these parts..

To reduce severe vibration caused by the pumping process, these pumps incorporate both a suction and discharge pulsation dampener. These are connected to the inlet and outlet of the fluid end.

The power end converts the rotation of the drive shaft to the reciprocating motion of the pistons. In most cases a crosshead crank gear is used for this.

A mud pump is composed of many parts including mud pump liner, mud pump piston, modules, hydraulic seat pullers, and other parts. Parts of a mud pump: 1. housing itself, 2. liner with packing, 3. cover plus packing, 4. piston and piston rod, 5. suction valve and discharge valve with their seats, 6. stuffing box (only in double-acting pumps), 7. gland (only in double-acting pumps), 8. pulsation dampener.

There are two main parameters to measure the performance of a mud pump: Displacement and Pressure.

Displacement is calculated as discharged liters per minute, it is related with the drilling hole diameter and the return speed of drilling fluid from the bottom of the hole, i.e. the larger the diameter of drilling hole, the larger the desired displacement. The return speed of drilling fluid should reach the requirement that can wash away the debris and rock powder cut by the drill from the bottom of the hole in a timely manner, and reliably carry them to the earth surface. When drilling geological core, the speed is generally in range of 0.4 to 1.0 m^3/min.

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Wikipedia