Arctic offshore drilling by Royal Dutch Shell PLC drew protests on two continents this year, but a more modest proposal for extracting petroleum where polar bears roam has moved forward with much less attention. While Shell proposed exploratory wells in the Chukchi Sea about 80 miles off Alaska’s northwest coast, a Texas oil company wants to build a gravel island as a platform for five or more extraction wells that could tap oil 6 miles from shore in the Beaufort Sea. The U.S. Bureau of Ocean Energy Management is deciding how to assess the environmental effect of a production plan...