Why Oilwells Leak: Cement Behavior and Long-Term Consequences

SPE 64733
Why Oilwells Leak: Cement Behavior and Long-Term Consequences
Maurice B. Dusseault, SPE, Porous Media Research Institute, University of Waterloo, Waterloo, Ontario; Malcolm N.
Gray, Atomic Energy of Canada Limited, Mississauga, Ontario; and Pawel A. Nawrocki, CANMET, Sudbury, Ontario
Society of Petroleum Engineers Inc. (2000)

Author(s):
Maurice B. Dusseault

Date:
11.2000

Key findings:

• 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 per-meability.
• 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./li>

Source / Publisher:
Society of Petroleum Engineers

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