SAN FRANCISCO — BP Plc. is shutting down its Prudhoe Bay oil field in Alaska, taking some 400,000 barrels a day of crude oil off the world market, following BP ) , one of the three major operators in the North Slope, was disclosed Sunday night and is expected to take several days to complete, The Wall Street Journal reported in its online edition. See Wall Street Journal story. (Subscription required.) The reduction represents almost half the total daily production from the North Slope, and about 8% of daily U.S. output. The fields are a major source of crude for U.S. refineries, particularly in California, the largest market in the U.S. for gasoline. BP, Exxon Mobil Corp. The reduction comes when global supplies are tight and prices have been volatile because of the Middle East crisis and other issues. In global electronic trading, crude-oil futures for September delivery rose as much as $1.23 a barrel, to $75.99, after BP reported the shutdown. The September contract settled at $74.76 Friday on the New York Mercantile Exchange, up 2.1% for the week. BP officials said they wouldn’t resume production at Prudhoe Bay until they and government regulators can be […]