A large valve at the top of a well that may be closed if the drilling crew loses control of formation fluids. By closing this valve (usually operated remotely via hydraulic actuators), the drilling cr [..]

  A stack or an assembly of heavy-duty valves attached to the top of the casing to control well pressure; a “Christmas tree”.

A "BOP" is a large, specially designed valve that is mounted on top of the well during the drilling and completion stages of operation. The operator can close this valve to stop the flow of [..]

The equipment installed at the wellhead to control pressures in the annular space between the casing and drill pipe or tubing during drilling, completion, and workover operations. See also Christmas t [..]

A large valve at the top of a well that workers can close if control of formation fluids is lost. By closing this, workers can increase mud density, then open the BOP and regain pressure control of th [..]

The equipment installed at the wellhead for the purpose of controlling rig pressures in the annular space between the casing and drill pipe (or tubing) during drilling, completion and certain worko [..]

Heavy-duty equipment installed at the wellhead during drilling and completion operations that contains special gates or rams that can be closed around the drill pipe or choke off the flow from a well.

A large, specially designed valve that is mounted on top of the well during the drilling and completion stages of operation. The operator can close this valve to stop the flow of oil or gas in case of [..]

One of several valves installed at the wellhead to prevent the escape of pressure either in the annular space between the casing and drill pipe or in the open hole (i.e., hole with no drill present) during drilling completion operations. Blowout preventers on land rigs are located beneath the rig at the land's surface; on jack-up or platforms [..]

A mechanical device designed to prevent oil from escaping a well during the process of drilling. Called BOP for short. Blowout preventers come in two varieties: ram style and annular. In general, both [..]