US oil sale helps offset SPR cavern shrinkage

A sale last year from the U.S. emergency crude-oil reserves has helped offset shrinking capacity, or “creep,â€‌ at the 62 salt caverns in Texas and Louisiana that form the Strategic Petroleum Reserve (SPR), the Energy Department’s inspector-general said Tuesday. A geological force called creep causes the caverns, which hold up to 727 million barrels of oil, to shrink at a rate that can reduce capacity by 1 million to 2 million barrels per year. The company that operates the SPR for the government, DM Petroleum Operations Company, conducts routing “leaching,â€‌ or the blasting of fresh water at the caverns’ walls to dissolve salt and maintain the capacity. The SPR currently holds about 695 million barrels after the 2011 sale and a loan of 1 million barrels to Marathon Petroleum Corporation after Hurricane Isaac in August caused delays and outages at refineries and production facilities.