Publications Details

Origin, diagnostics, and mitigation of a salt dissolution sinkhole at the US Strategic Petroleum Reserve storage site, Weeks Island, Louisiana

Neal, J.T.

A sinkhole was observed over the edge of the two-level former salt mine that was converted for oil storage. Diagnostic studies suggest a direct connection exists between the surface collapse area and the underground mine as shown by correlative measurements of sediment slump rates and probable brine influx into the mine. The dissolution of salt below the sinkhole that initiated the leak into the mine was likely caused by several confluent geologic processes, and exacerbated by mining-induced stresses that created fractures which served as hydrologic flowpaths. Modelling studies of mine stresses show that years may be required before tensional cracking begins to occur, but once begun can continue to develop, and relieve the stress in that specific regime. The crack regime creates the avenue for incursion of groundwater. Mitigation measures include increasing the mine pressure, slowing the dissolution by injecting brine into the sinkhole throat, and construction of a freeze curtain to restrict hydrologic flowpaths. -from Authors