The U.S. Department of Energy will shut down the 73 million bbl Weeks Island, La., Strategic Petroleum Reserve (SPR) cavern and move the mainly sour crude oil to other sites in Louisiana and Texas.
DOE said groundwater seeping into the underground storage chambers is compromising the geologic integrity of the site and poses an unacceptable environmental risk to nearby land and water ecosystems (OGJ, June 20, Newsletter).
The five SPR sites, all on the Gulf Coast, hold 590 million bbl of crude oil and have capacity to store 750 million bbl. Closing Weeks Island will reduce total capacity to 677 million bbl.
DOE plans to move 60 million bbl of Weeks Island oil to the Big Hill, Tex., storage site and 13 million bbl to the Bayou Choctaw, La., site. Those locations have trouble with natural gas intrusion (OGJ, Oct. 10, p. 90).
The Weeks Island site, in New Iberia Parish, will be decommissioned 2-3 years after the oil is removed and environmental reviews are complete.
WHAT'S WRONG
After an extensive study at Weeks Island, DOE determined water was seeping into the 550 ft deep chambers through a sinkhole and a fracture in the top of the salt dome.
Although the water flow is relatively slow-it has been compared with the flow from a garden hose-DOE said the integrity of the storage chambers could be compromised.
DOE tried to stop the flow by pressuring up the caverns through injection of another 1 million bbl of oil. it also is injecting saturated brine into the sinkhole to reduce groundwater leaching, and that has slowed water intrusion. But it has found no technically feasible, long term solutions.
DOE fears the groundwater ultimately could dissolve enough of the surrounding salt to permit a washout, a sudden surge of water that could force oil upward through the chambers to aquifers near the surface.
Weeks Island is less than 1 mile from an inlet leading to Vermilion Bay in the Gulf of Mexico. A DOE spokesman said, "We had the potential for catastrophic environmental damage."
It will cost $75-100 million to move the oil and decommission the site, but closing it will save an estimated $95 million in operating and refurbishing costs during the next 10 years.
Water intrusion presents a problem in removing the oil. The caverns normally would be drawn down by using submersible pumps that are not designed to lift water. As oil is removed, the water level will rise, requiring the pumps to be raised continually.
DOE will examine other possible uses for the 7 acre Weeks Island site.
DOE acquired Weeks Island in 1977 in the early buildup of the SPR. It is the only storage site converted from a room and pillar salt mine. The others are leached salt dome caverns.
Copyright 1994 Oil & Gas Journal. All Rights Reserved.
Issue date: 12/26/94
