ABSTRACT
The Bryan Mound site has three caverns whose unusual shapes and dimensions have caused concerns about cavern collapse, sinkhole formation, and loss of accessibility to stored oil. The abandoned Cavern 3 is a 400-m diameter cavern which was constructed for brine production and storage in the 1940s and plugged and abandoned in 1980. Surface subsidence measurements show an unexpectedly larger subsidence rate over Cavern 3 than the rest of the site, possibly indicating that this cavern may be losing pressure, which would affect boreholes for nearby storage caverns. Cavern 2 is a similar cavern of about 200 m in diameter used for oil storage. Its location high in the salt dome raises
1 INTRODUCTION
The US Strategic Petroleum Reserve (SPR), operated by the U.S. Department of Energy (DOE), stores crude oil in 62 caverns located at four different sites in Texas (Bryan Mound and Big Hill) and Louisiana (Bayou Choctaw and West Hackberry). The petroleum is stored in solution-mined caverns in salt dome formations. The SPR sites are varied in terms of cavern structure and layout. Most of the caverns at these sites were built as vertical cylinders of reasonably uniform cavern dimensions (radius, height, shape, and depth) and spacing. However, several caverns at these sites, particularly those constructed prior to SPR ownership, are characterized by diverse cavern characteristics. Sometimes these unusual cavern shapes present technical problems due to the resulting increased subsidence and shear stresses.
