Exxon Mobil Corp. warned that it may be forced to eliminate almost 20% of its future oil and gas prospects, yielding to the sharp decline in global energy prices.  Under investigation by the U.S. Securities and Exchange Commission and New York state over its accounting practices—and the impact of future climate change regulations on its business—Exxon on Friday disclosed that some 4.6 billion barrels of oil in its reserves, primarily in Canada, may be too expensive to tap.  Exxon is facing near- and long-term threats as it seeks to exploit the full value of a vast oil and gas portfolio that stretches from Texas to the Caspian Sea, and deliver the handsome dividends that its shareholders have come to expect since it was part of John D. Rockefeller’s Standard Oil.  Today, the company is suffering amid a two-year plunge in oil prices that has a barrel trading for around $50, a level Chief Executive Rex Tillerson believes may linger as U.S. shale producers ramp up at the first uptick in prices, prolonging the current glut and putting a ceiling on any price upswing.  Earlier this year, Exxon lost the triple-A bond rating it had held from Standard & Poor’s Rating Services since 1930, a standing of creditworthiness shared with just two other companies, Microsoft Corp. and Johnson & Johnson. Last year, it failed to find enough new oil and gas to replace what it produced for the first time in 20 years. Its profits in the last 12 months are the lowest since 1999, before it merged with Mobil Corp.  Exxon is alone among major oil companies in not having written down the value of its future wells as prices fell. It has said it follows conservative practices in booking reserves. It now plans to examine its assets to test, under rules governed by accounting standards, whether they are worth less than carried on its books.  The company said the 20% reserves reductions, which are governed separately by SEC rules, may be necessary based on the average 2016 price by the end of the year, though higher prices in November and December could mitigate the extent of the decline. It added that any reserve reductions could be added back if prices recover.  In an investor call on Friday, Exxon declined to discuss potential reserve write-offs or accounting write-downs in detail beyond its statement. The SEC declined to comment on Exxon’s disclosure.  “Exxon has long been the best at what they do, but these external constraints are putting them more in line with everyone else, forcing them to the level of their competitors,” said Sean Heinroth, a principal in the energy practice at management consultancy A.T. Kearney.  Though Exxon didn’t mention climate change or regulators in its disclosure, most of the assets it said may not be economic are among the most scrutinized by climate change activists: Canada’s oil sands.  Since 1999, energy companies have invested more than $200 billion in Alberta’s oil sands, which has the third largest oil reserves behind Venezuela and Saudi Arabia, says the Canadian Association of Petroleum Producers.  Nine of the world’s top oil companies, including Exxon, Chevron and Royal Dutch Shell PLC, have been counting on wringing more Canadian crude from the ground in the coming decades. Combined, Canadian crude accounts for 23% of the firms’ proven reserves, according to data from investment bank Peters & Co.—up from only 5% in 2006.  New investments in the oil sands may be much harder to come by after Exxon’s announcement, said Andrew Logan, director of the oil and gas program at Ceres, a Boston-based nonprofit that has pushed Exxon and other companies for better disclosure on the potential impact of climate change on the energy business.  “Why would any company invest billions of dollars in a new oil sands project now, given the near certainty that the world will be transitioning away from fossil fuels during the decades it will take for that project to pay back?” Mr. Logan said.  The potential loss of reserves has broad ramifications for Canada, which depends on the development of its crude stores to support its economy, but like other western countries has been moving to strengthen regulations to address climate change. Canadian Prime Minister Justin Trudeau earlier this month unveiled a national carbon-pricing proposal, sparking an immediate clash between the national government and the province of Alberta.  The Liberal government’s proposal to charge a price for carbon emissions compounds the headwinds energy companies already face if they want to mine Canada’s oil sands for decades to come.  Amy Myers Jaffe, executive director for Energy and Sustainability at University of California, Davis, said Exxon’s warning signals that it doesn’t believe oil prices will rise significantly in the near future.  “This company had positioned itself for growth and oil sands were a key part of its strategy,” she said, adding: “If lots of companies have to do write downs on their Canadian reserves, it sends a gloomy message about the oil sands,” she said.  Longer term, Exxon faces headwinds from regulations aimed at reducing carbon dioxide and other greenhouse gas emissions, measures that are widely expected to fall most heavily on its industry.  Exxon’s other major obstacle: U.S. competition. Advanced shale drilling techniques have unleashed a new wave of American oil into world markets. Those drilling and fracking techniques have made smaller American companies the industry’s new “swing producers,” or those most able to ramp up output quickly.  Exxon’s Mr. Tillerson acknowledged that prospect in a recent speech at a conference in London where other energy executives were forecasting a sharp supply shortfall in coming years.  “I don’t necessarily agree with the premise,” he said.  Exxon shares fell 2.5% to $84.78 at 4 p.m. in Friday trading after reporting a quarterly profit that declined 38% compared with a year ago.  Write to Bradley Olson at Bradley.Olson@wsj.com and Lynn Cook at lynn.cook@wsj.com
Exxon Mobil said it may be forced to recognize that billions of barrels of its reserves are no longer profitable to produce. The disclosure came as the oil producer reported a 38% decline in quarterly profit.