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Mud Gas Separator for drilling rig

2013-09-04

A MUD GAS SEPARATOR (MGS), or gas buster, is common on most drilling rigs throughout the world. The MGS is used to separate wellbore gas from the drilling fluid while circulating out a kick or circulating any gas present in drilling fluids during drilling or workover operations. 

Mud Gas Separator


The MGS is a very important component in underbalanced drilling. A typical MGS is constructed of a cylindrical vessel with a series of baffles in it. The drilling fluid from the wellbore enters the MGS, and the action of the fluid hitting the baffles separates easily removed gas from the fluid. The gas exits through a vent line at the top of the MGS and is safely vented away from the rig floor. The mud exits the MGS through a line near the bottom of “up hill” to return to the pit system.

Typically, the maximum allowable pressure of the MGS when in use is determined by the fluid leg or (fluid seal) height. The density fluid in the fluid leg is dependent on the fluid in use at the time, and, therefore, operating pressure of the system is variable. This pressure is usually below 15 psig. However, there are MGS applications in which the vessel can operate at pressures up to 100 psi.

The friction pressure of the gas flowing through the vent line must be less than the hydrostatic pressure of the fluid in the fluid leg. If this friction pressure is greater than the hydrostatic pressure in the fluid leg, gas will exit the fluid line and flow to the pit system.