1. n. [Drilling]

The system of spools, valves and assorted adapters that provide pressure control of a production well.

See related terms: casing string,  casinghead,  day rate,  Texas deck

2. n. [Well Completions]

The surface termination of a wellbore that incorporates facilities for installing casing hangers during the well construction phase. The wellhead also incorporates a means of hanging the production tubing and installing the Christmas tree and surface flow-control facilities in preparation for the production phase of the well.

See related terms: casing hanger