Offshore drilling, particularly in deep waters, is some of the most expensive exploration done by oil companies around the world. Nevertheless, since the 2010 BP Deepwater Horizon disaster that left 11 workers dead and soiled hundreds of miles of beaches, and the one-year drilling moratorium that followed, production in the gulf has flourished.

The Energy Department on Wednesday noted that with a total of 13 production projects coming on line this year and next, output in the gulf would increase from an average of 1.4 million barrels a day in the fourth quarter of 2014 to 1.6 million barrels a day in late 2016. That surge will partly offset an expected decline in onshore production because oil companies have reduced their rig count on land by more than 60 percent since last year.

The Energy Department, in its short-term energy outlook, projected a domestic production increase from an average of 8.7 million barrels a day last year to 9.4 million barrels a day in 2015 before overall output declines to nine million barrels next year. The resilient production in the United States, with rising production from Iraq and Saudi Arabia, has produced a surplus of oil around the globe of an estimated two million barrels a day.

One outgrowth of that surplus is the challenge of where to put all the oil.

Domestic storage alone rose 2.6 million barrels in mid-August, the report noted, because of an unexpected surge in imports and a drop in refinery processing after a breakdown in the BP refinery in Whiting, Ind.

Current crude stockpiles of 456 million barrels in the United States are at levels rarely if ever seen at this time of year since World War II. Once the summer driving season ends and other regional refineries begin their seasonal retooling, the domestic glut of crude is likely to grow even larger and the price of oil and gasoline will fall further, analysts said.

The Energy Department forecast that the American benchmark oil price would average $49 a barrel this year, $6 lower than it estimated last month. It forecast a price of $54 in 2016, $8 lower than it projected last month.

“Concerns over the pace of economic growth in emerging markets, continuing (albeit slowing) supply growth, increases in global liquids inventories, and the possibility of increasing volumes of Iranian crude entering the market contributed to the changed forecast,” the department report said.