1. n. [Drilling]

The engineering plan for constructing the wellbore. The plan includes well geometries, casing programs, mud considerations, well control concerns, initial bit selections, offset well information, pore pressure estimations, economics, and special procedures that may be needed during the course of the well. Although drilling procedures are carefully developed, they are subject to change if drilling conditions dictate.

See: offset well,  pore pressure,  well control