Publications Details
Analyzing the effect of large pressure changes on the operational stability of large-diameter caverns for the strategic petroleum reserve
This paper presents a case study of how large-scale computational analyses may be used in conjunction with site data to make recommendations for safe depressurization and repressurization of oil storage caverns in domal salt with unusual geometries and close proximity. These recommendations were developed in response to a wellbore casing failure, and further utilized to assess ongoing cavern storage operations. Two caverns at West Hackberry present such concerns due to their unusual shapes and close proximity to each other. Cavern 6 at West Hackberry has an unusual dish-like shape with a large rim around the circumference. The diameter of Cavern 6 at the ceiling ranges from 340 to 380 meters. Because of the shape of the cavern and the creep behavior of salt, Cavern 6 is prone to wellbore casing failures caused by tensile strains. In addition, Cavern 6 has a greater potential for tensile cracking of salt at the perimeter of the cavern during a period of increasing pressure, such as at the end of a workover procedure. Cavern 6 is in close proximity to Cavern 9, which is hourglass-shaped. The analyses presented here were used to develop guidance for general pressurization procedures for the operation of these two caverns. Copyright 2013 ARMA, American Rock Mechanics Association.