Energy giant says 4.6 billion barrels of reserves at risk Company produces least oil, natural gas in seven years Exxon Mobil Corp. warned it may be facing the biggest reserves revision in its history as production sank to a seven-year low and profit slid amid a prolonged slump in energy markets. About 3.6 billion barrels of reserves in the Canadian oil sands and the equivalent of another 1 billion barrels of oil in other North American fields may be in jeopardy if the average energy prices seen during the first nine months of 2016 persist, Exxon said in a statement on Friday. That would equate to 19 percent of Exxon’s reserves and would be the largest de-booking since the 1999 merger that created the company in its modern form. Exxon’s accounting has prompted a U.S. Securities and Exchange Commission investigation into whether the company should have written down assets […]