Technical Guidance Document Number 9: Casinghead Gas Venting

This document provides technical guidance to Partners of the CCAC Oil and Gas Methane Partnership (OGMP). It is one in a series describing a core source of methane emissions from oil and natural gas production operations. The guidance documents introduce suggested methodologies for quantifying methane emissions from specific sources and describe established mitigation options that Partners should reference when determining if the source is “mitigated.”

Casinghead gas is gas that collects in the annular space between the casing and tubing in an oil well. Usually beneficial, casinghead gas forces the produced oil up the tubing. In a mature oil well equipped with a beam pump or electric submersible pump, however, this gas can begin restricting oil flow, decreasing a well’s production by vapor locking the pump. Combined with the backpressure of an oil well’s surface equipment, pressure from casinghead gas can severely restrict production. Partners must remove casinghead gas pressure build-up in a well’s annular space to maintain production. The most common method to do this is to vent the casinghead gas to the atmosphere at or near the wellhead.
Casinghead gas venting can occur, and may be mitigated, in a variety of ways. Partners are encouraged to identify and deploy appropriate controls for each oil well.