Chevron experienced four casing leaks in subsea deepwater environments with an estimated cost of $80 million to remediate the wells. A similar incident at BHP resulted in parted casing and cost the company an estimated $21 million. This paper describes the investigative techniques which led to the conclusion of heat checking as the likely root cause of the casing leaks and the development of a 3D static FEA model which predicts downhole casing temperature. The model was validated by historical data analysis of more than 20 deepwater wells and found strong correlations between predicted downhole casing temperature and casing leak incidents. The results provided confidence for the implementation of a drilling parameter window and real-time temperature prediction algorithm to monitor and mitigate the potential for heat checking. The intent of this paper is to share with industry the recent realization and understanding of heat checking as a casing failure mode and mitigation measures put in place to manage a known but not necessarily widely monitored risk.
Number of Pages
API RP 96, First Edition, March 2013
Eaton, L. F. (1993). Tool Joint Heat Checking While Predrilling for Auger TLP Project. Paper presented at the SPE/IADC Drilling Conference, Amsterdam, The Netherlands.
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