National Strategic Crude Oil Storage in the Weeks Island Dome Salt Mine—Part I: Geotechnical Evaluation

This paper, the first in a series of two, presents the results of a geotechnical evaluation of the Weeks Island dome salt mine. The purpose of the evaluation was to confirm the suitability of the underground facility for the long-term storage of crude oil under the Federal Energy Administration’s Strategic Petroleum Reserve Program. The Weeks Island mine, currently operated by the Morton Salt Company, is located in a salt dome on the Gulf Coast south of New Iberia, Louisiana. The mine has two levels of workings, at depths of approximately 185 and 245 m (600 and 800 ft) with development by the room-and-pillar mining technique. Geologic features of interest within the mine include zones of vertical banding and folding, shear zones, and blowouts. Field testing indicated that the salt mass is, for all intents and purposes, impermeable. Brine and oil leaks and gas seeps were examined and thought to be localized phenomena that did not affect mine stability and should not affect crude oil containment. The 23-m- (75-ft-) high pillars are generally intact with minor to severe spalling, generally in older areas of the mine. The mine roof exhibits no signs of distress or failure. Based on the overall results of the geotechnical and rock mechanics evaluations, the existing salt mine facility at Weeks Island was certified as suitable for the long-term storage of crude oil.