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wellhead

1. n. [Drilling]
The system of spools, valves and assorted adapters that provide pressure control of a production well.

Wellhead components
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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.