Rigless well abandonment remediation in the shallow water U.S. Gulf of Mexico

From 2004-2015, over 11,000 wells were plugged and abandoned in the federal waters of the Gulf of Mexico, but no studies have ever been conducted on the reliability of operations and the frequency of remediation activity. The purpose of this paper is to estimate the probability that a dry tree well abandoned using rigless methods, the most common approach in the shallow water Gulf of Mexico, requires remediation after initial operations are completed. A random sample of 502 platform wells abandoned in 2010 in water depth less than 400 ft were tracked for five years to identify bubbling/leaking events. Nine wells were identified that required remediation after operations were performed leading to a remediation probability estimate of 1.8% and a 95% confidence interval ranging between 0.6 and 3.0%. The limitations of the analysis and directions for future work are described.