BOP Stack

A "BOP Stack" is a set or group of "blowout preventers" that are found on every oil and natural gas drilling rig

as well as the oil and/or natural gas well. BOP stack is typically located below the rig floor and after the drilling rig

is removed, is at the top of the well.A set of two or more BOPs used to ensure pressure control of a well. A typical

BOP stack might consist of one to six ram-type preventers and, optionally, one or two annular-type preventers. A

typical stack configuration has the ram preventers on the bottom and the annular preventers at the top. The configuration

 of the stack preventers is optimized to provide maximum pressure integrity, safety and flexibility in the event of a well

control incident. It is common to have an annular preventer or two on the top of the stack since annulars can be closed

over a wide range of tubular sizes and the openhole, but annular preventers are typically not rated for pressures as high

as ram preventers.The BOP stack also includes various spools, adapters and piping outlets to permit the circulation of

wellbore fluids under pressure in the event of a well control incident.