Publications Details
Long-term sealing analyses for US Strategic Petroleum Reserve (SPR) caverns
It is inevitable that sealing and abandonment will someday occur in a SPR cavern or caverns. To gain insight into the long-term behavior of a typical SPR cavern following sealing and abandonment, a suite of mechanical finite-element calculations was performed. The initial analyses predict how quickly and to what extent a cavern pressurizes after it is plugged. The analyses also examine the stability of the cavern as it changes shape due to the excessive pressures generated as the salt creeps and the brine in the cavern thermally expands. These large-scale analyses do not include the details of the plug but assume a good seal is established in the cavern wells. In another series of analyses, the potential for forming a leak at the plug is evaluated. A cement plug, emplaced in the casing seat of a cavern well, is loaded using the predicted brine pressures from the cavern analyses. The plugged casing analyses examine the potential for forming a leak path in and along the interfaces of salt, casing, and cement plug. In the last set of analysis, the dimensional scale of the problem is further reduced to examine a preexisting crack along a casing/salt interface. The cracked interface is assumed to be fluid filled and fully pressurized by the cavern fluids. The analyses address the potential for the fluid path to extend upwards along a plugged casing should an open microannulus surround the casing after it is plugged.