Despite sharply increased drilling activity, record high prices, and comfortable oil industry profit margins, America's oil and natural gas production is expected to decline throughout the 1980s and, at best, level off by 1990.

"It's simple, we're just going to have to run to stand still," says Sen. Henry M. Jackson, chairman of the Senate Energy Committee. The Washington Democrat's oft-repeated forecast of a downturn in conventional oil and gas output is increasingly shared by a number of major oil companies such as Shell and Exxon.

And more recently Congress' General Accounting Office has added yet another somewhat pessimistic assessment.

"It is very unlikely that U.S. petroleum and natural gas production can be increased above or even held at current levels," the GAO says, though it could be "stabilized" by 1990.

A similar view is offered by Gulf Oil Co. Chairman Jerry MCAfee, who says, "We'll do well just to stay level in domestic oil output during the next decade."

The United States currently produces about 10.2 million barrels of oil and natural gas liquids a day -- nearly 3 billion barrels of oil a year -- and 18.7 trillion cubic feet of natural gas annually. Proven domestic oil reserves are now listed at about 30 billion barrels, and proven gas reserves at 200 trillion cubic feet.

America now imports nearly half its total oil needs, and about 5 percent of the natural gas burned in American homes, factories, and businesses.

The steady decline in oil and gas production results from the simple fact that the nation's oil companies and consumers have been using oil and gas faster than new reserves have been discovered. Last year, for example, despite the 48,500 new wells drilled -- a near record level -- oil reserves dropped by 1.7 billion barrels, and gas reserves fell by 8 trillion cubic feet.

The GAO lays part of the difficulty to exploratory drilling trends. "Almost 90 percent of the increased drilling activity has been development wells," essentially adding new production facilities from known oil or gas fields. Meanwhile, the congressional watchdog agency says, "exploratory drilling activity has increased only one-third as fast as developmental drilling."

Oil companies, in other words, are not risking the largest share of their drilling on so-called unexplored frontier areas, and instead have gone after known producing formations.

The most attractive frontier drilling areas, according to oilmen at Exxon and Atlantic Richfield, are the outer continental shelf, Alaska, and some still unexplored onshore areas away from major producing states such as Texas and Oklahoma. Largely due to government policy on leasing, or unresolved environment and land issues, large portions of the shelf and Alaska have not been made available to the industry for drilling.

The disparity in drilling, however, remains.

Weeks after Texas Railroad Commission member Mack Wallace said that Texas, the nation's leading oil producing state, was "kind of picked over," former Alaska governor Walter J. Hickel complained about the limited drilling activity that has taken place in his state.

"Only seven oil rigs are at work in Alaska," Hickel said, "compared to 366 in Louisiana and 807 in Texas."

Alaska's massive, 9.6-billion-barrel oil field at Prudhoe Bay, discovered in the late 1960s arrested an earlier downturn in domestic oil production.

Hickel and another former Alaskan governor, William A. Egan, insist that the state's current 1.6-million-barrel-a-day oil production would be increased to 4.5 million barrels if oilmen were just turned loose in the state.

The GAO and some other analysts hold out a more optimistic view of natural gas prospects, saying gas production will not decline as quickly as oil output. The GAO says that gas production will drop from 18.4 trillion cubic feet in 1980 to 17.1 trillion cubic feet in 1985, and 16.8 trillion cubic feet by 1990.

As for the controversial Natural Gas Policy Act -- phasing out gas price controls -- which was passed last year after bitter congressional debate, the GAO says its benefits "will have largely disappeared by the mid-1980s."