A wellbore that has been unintentionally drilled in a direction other than vertical. It usually occurs where there is a section of alternating hard and soft […]

An assembly of sheaves mounted on beams at the top of the derrick and over which the drilling line is reeved. See block, reeve, sheave.

A rig that utilizes a hydraulically powered hoisting system with long stroke cylinders for pushing a sheave cluster and traveling assembly vertically. These cylinders and sheave […]