18 July 2017

Air-actuated

Powered by compressed air, as are the clutch and the brake system in drilling equipment. See choke.
18 July 2017

Cased

Pertaining to a wellbore in which casing has been run and cemented. See Casing.
25 July 2017

Fail-safe

Said of equipment or a system so constructed that, in the event of failure or malfunction of any part of the system, devices are automatically activated […]
18 July 2017

Impermeable

Preventing the passage of fluid. A formation may be porous yet impermeable if there is an absence of connecting passages between the voids within it. See […]