308,000 Barrels of oil go missing?

The Government Auditors looked into the Department of Energy's management of the oil received for Strategic Petroleum Reserve, which is a critical program to assure energy stability in the U.S. in case of an oil crisis. Needless to say that when it was discovered that 308,000 barrels of oil go missing, the government auditors asked the question of how could you not notice when that much oil goes missing?

During the examination it was discovered that in 28 percent of oil transfers the amount received did not match the estimated amount to be shipped by the Interior Department's Minerals Management Service. -- In 2005 there were some discrepancies of barrels of oil reported to be received not equal to what was shipped. That discrepancy was never fixed. -- In 2007 the Government Accountability Office investigated the Interior Department's MMS for losing track of billions of dollars in royalties.

So how does 308,000 barrels of oil disappear without anyone noticing?