Publications
Leak Testing and Implications of Operations to Locate Leak Horizons at West Hackberry Well 108
Sattler, Allan R.; Ehgartner, Brian L.
The Strategic Petroleum Reserve site at West Hackberry, Louisiana has historically experienced casing leaks. Numerous West Hackberry oil storage caverns have wells exhibiting communication between the interior 10 3/4 x 20-inch (oil) annulus and the ''outer cemented'' 20 x 26-inch annulus. Well 108 in Cavern 108 exhibits this behavior. It is thought that one, if not the primary, cause of this communication is casing thread leaks at the 20-inch casing joints combined with microannuli along the cement casing interfaces and other cracks/flaws in the cemented 20 x 26-inch annulus. An operation consisting of a series of nitrogen leak tests, similar to cavern integrity tests, was performed on Cavern 108 in an effort to determine the leak horizons and to see if these leak horizons coincided with those of casing joints. Certain leaky, threaded casing joints were identified between 400 and 1500 feet. A new leak detection procedure was developed as a result of this test, and this methodology for identifying and interpreting such casing joint leaks is presented in this report. Analysis of the test data showed that individual joint leaks could be successfully identified, but not without some degree of ambiguity. This ambiguity is attributed to changes in the fluid content of the leak path (nitrogen forcing out oil) and possibly to very plausible changes in characteristics of the flow path during the test. These changes dominated the test response and made the identification of individual leak horizons difficult. One consequence of concern from the testing was a progressive increase in the leak rate measured during testing due to nitrogen cleaning small amounts of oil out of the leak paths and very likely due to the changes of the leak path during the flow test. Therefore, careful consideration must be given before attempting similar tests. Although such leaks have caused no known environmental or economic problems to date, the leaks may be significant because of the potential for future problems. To mitigate future problems, some repair scenarios are discussed including injection of sealants.