Abstract

Annular gas flow following casing cement jobs is a primary problem in some areas of Southeast Asia. It can be controlled in most cases if companies are aware that the problem may exist in their proposed well. Simple hand calculation can be applied to determine if there is a gas flow problem and its severity. This can assist in deciding which methods are needed to help keep a well under control following a cement operation.

Well conditions effect gas flow after a cement operation. Flow problems may be combatted by modifying well parameters such as over-balanced pressure. This can be accomplished by increasing hydrostatic pressure, shortened cement columns, using stage cementing practices and casing packers.

Some cement slurry properties influence gas flow following a cementing operation. These include fluid loss of the cement, free water, static gel strength, and cement compressibility. One must compare compressible cement slurries, know when to select foam cement, when to use gas generated cement compositions, and when neither is suitable.

Computer programs are available to help determine how severe the gas flow problem is, how well conditions can be modified, and what cement slurry would best combat the problem.