1. n. [Drilling]

A valve usually used in well control operations to reduce the pressure of a fluid from high pressure in the closed wellbore to atmospheric pressure. It may be adjusted (opened or closed) to closely control the pressure drop. Adjustable choke valves are constructed to resist wear while high-velocity, solids-laden fluids are flowing by the restricting or sealing elements.

See: choke,  choke line,  choke manifold,  well control

2. n. [Well Completions]

A valve, located on or near the Christmas tree that is used to control the production of fluid from a well. Opening or closing the variable valve influences the rate and pressure at which production fluids progress through the pipeline or process facilities. The adjustable choke is commonly linked to an automated control system to enable the production parameters of individual wells to be closely controlled.

See: choke