Mud engineer

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A mud engineer (often referred to as a "Mud Man") is an outside contractor, whose purpose is to determine the correct mud, also called drilling fluid, to use for a borehole, advising treatment and monitoring its condition. Main properties monitored are density, viscosity, chemical parameters and solids content. If properties divert from mud program the mud engineer will notify the Derrickhand and company man and advise the correct treatment. Mud is a vital part of the drilling operation, it lubricates the bit, carries the drill cuttings and suspends them for as long as possible if mud circulation stops. Drilling Fluid also maintains the wellbore pressure. The mud engineer is of vital assistance to rig operaions and often stays on the rig site, supplied with their own caravan and lab.

One of the most important mud properties is the mud weight (density). If the mud weight exceeds the fracture pressure of the formation, the formation may rupture and large quantities of mud are lost inside it, in a situation referred to as lost circulation. These cracks can also cause water to seep into the well bore or into a hydrocarbon bearing zone, which would likely impede the ability of the formation to produce oil (or require the separation of large quantities of water).

Conversely, if the mud weight is too low it will have a hydrostatic pressure that is less than the formation pressure. This will cause pressurized fluid in the formation to flow into the wellbore and make its way to the surface. This is referred to as a formation "kick" and can lead to a potentially deadly blowout if the invading fluid reaches the surface uncontrolled.

Other important mud properties to be maintained are the YP (Yield Point) which determines the carrying capacity of the mud to suspend and carry the drill cuttings and the ability of the mud to form mud cake.

See also Derrickhand