gas swellable seals for gas migration prevention

Seal units prevent gas/fluid movement at the interface between the outer surface of the casing and the inside of the cement sheath. in spite of the improved practice of releasing pressure on the casing after the top plug bumps, investigations by different research and development groups confirm that leakage at this interface is very possible. when subjected to differential pressures, often encountered in completing or producing a well, inter-zonal communication at this point will occur, like “channeling” in the remainder of the annulus. this will prevent efficient production of the producing zone or cause stimulation work (fracturing, acidizing, etc.) to be ineffective due to uncontrolled fluid migration in the annulus.