Crude markets already in a downward spiral sank under the weight of a supply report showing growing stockpiles of oil after a major U.S. Midwest refinery shutdown. And the oversupply may just be getting started. A heavy slate of refinery maintenance in the region this fall threatens to make inventory builds in Cushing, Oklahoma, a common occurrence. The outages will follow trouble at BP Plc’s Whiting refinery in Indiana that meant about 1.5 million barrels of oil didn’t get consumed last week. “There is a lot of maintenance scheduled in the fall,” said John Auers, senior vice president at Turner Mason & Co., a Dallas-based energy consultancy. “Having a lot of plants down for turnarounds tends to push us into an oversupply situation and starts widening out the domestic-international spread.” Heavy refinery outages would leave more crude to fill storage tanks, forcing U.S. prices to fall to encourage shippers […]