Loss of zonal isolation in a wellbore can be caused by mechanical failure of the cement or by development of a microannulus. However, behavior of the sealant is driven by specific boundary conditions such as rock properties. Large-scale laboratory testing of the cement sheath in an annular geometry and a confined situation was performed to simulate various downhole stress conditions and evaluate the behavior of several sealants. Failure modes of the cement sheath were determined as a function of cement mechanical properties, loading parameters, and boundary conditions. Results were used to validate an analytical model that predicts cement-sheath failure.

Keywords:
permeability, expansion, zonal isolation, spe drilling, cement system, cement property, cement formulation, march 2005, 7-mm-ring configuration, cement chemistry
Subjects:
Casing and Cementing, Cement formulation (chemistry, properties), Wellbore Design
Copyright 2005, Society of Petroleum Engineers
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