Oil and gas wells can develop gas leaks along the casing years after production has ceased and the well has been plugged and abandoned (P&A). Explanatory mechanisms include channelling, poor cake removal, shrinkage, and high cement permeability. The reason is probably cement shrinkage that leads to circumferential fractures that are propagated upward by the slow accumulation of gas under pressure behind the casing. Assuming this hypothesis is robust, it must lead to better practice and better cement formulations

Keywords:
cement shrinkage, mechanism, upstream oil & gas, circumferential fracture, leakage, shrinkage, alberta, dusseault, nawrocki spe 64733, cement formulation
Subjects:
Casing and Cementing, Cement formulation (chemistry, properties)
Copyright 2000, Society of Petroleum Engineers
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