دیکشنری تخصصی مهندسی نفت - نسخه آنلاین

n: a structural steel, opensided tower raised vertically by special lifting tackle attached to the travelling block. See mast. Compare standard derrick.

n: a drilling rig d1at has a jackknife mast instead of a standard derrick.

n: a derrick that is built piece by piece at the drilling location, as opposed to a jackknife mast, which is preassembled. Standard derricks have been replaced almost totally by jackknife masts. Compare mast.

n: The derrick that four legs extended to crown block and fixed with base in the mouth of a well.

n: a portable mast constructed of angular as opposed to tubular steel members. See jackknife mast.