Washington — Some energy experts now say they see forces at work which, by tightening up energy supplies, could later this decade put the Organization of Petroleum Exporting Countries (OPEC) back in a position to drive up oil prices.
Recently consumers have enjoyed a number of pleasant pocketbook effects - including lower gasoline prices and subdued inflation - because OPEC has lost some of its grip on the world oil market.
These gains for consumers are threatened by a number of things, energy forecasters say.
For example, some expect a tightening in the currently abundant supplies of natural gas, an alternative to oil. Meanwhile, recent reductions in oil prices make the search for new domestic oil less appealing and dampen interest in developing new alternatives to oil. At the same time, lower energy prices tend to take the steam out of new efforts to conserve fuel.
''I see a resumption in the decline of US oil production,'' from the current 10 million-barrel-a-day level to about 7 million barrels, says Daniel Yergin, associate director of the Harvard University Energy Security Program. ''The more people say prices will go down and stay down, the more I think prices will go up.''
The same forces are also at work in European industrial countries. ''Supplies in industrial countries may begin to decline in the second half of the 1980s if (energy prices) do not firm up,'' says Herman Franssen, chief economist of the International Energy Agency, which is part of the Organization for Economic Cooperation and Development, a group of major Western industrial powers.
So, even if conservation holds energy demand below levels reached in the 1970 s, ''supplies outside OPEC and natural gas and coal conversion may not come through,'' Mr. Franssen says. ''Later on . . . OPEC may have a much stronger share of world oil markets and could be back in the driver's seat again.''
''Any sudden increase in energy consumption would have to be translated into demand for OPEC. It is the swing producer,'' adds James E. Akins, a private energy consultant and former US ambassador to Saudi Arabia.
Of course, not all forecasters see OPEC regaining a significant portion of its power to boost oil prices sharply. The supply potential of long-term oil development prospects in the Arctic and offshore from California, Newfoundland, and the China Sea are enough ''to more than offset depletion in currently producing fields,'' argues Bruce C. Netschert, vice-president of National Economic Research Associates, a consulting firm.
''An oil price somewhere between $25 and $30 per barrel in 1983 dollars should be enough to meet modest world demand growth and thus forestall an oil price increase in real terms,'' Mr. Netschert said in a recent speech.
And energy forecasting is a notoriously difficult business. ''Along with (the current) surplus of oil is a surplus of confusion,'' Mr. Yergin admits. Most forecasts about the energy outlook assume that strife in the Middle East will not cause a major disruption in the flow of oil. ''All the talk about OPEC assumes political and military tranquillity in the Middle East and the rest of OPEC. It is a daring and unwarranted assumption,'' Mr. Akins, the energy consultant, warns.
Among the events that could seriously disrupt oil supplies, experts say, is an escalation in the war between Iran and Iraq, with sustained bombing of major oil facilities. Or the war could spread to include other oil-producing nations in the region. Finally, Saudi Arabia could undergo a political upheaval that would disrupt the flow of oil. But such an upheaval is unlikely to happen, analysts say.
Still, ''there are some danger signs. So it is a great mistake to become complacent and (think) the danger of a supply interruption is over,'' says William Quandt, director of energy and national-security studies at the Brookings Institution, a research organization in Washington.
''There still is an energy problem and an energy security problem and the Middle East is part of that,'' Mr. Quandt says. Messrs. Quandt, Akins, Yergin, and Franssen spoke at a recent conference sponsored by the School of Advanced International Studies at Johns Hopkins University on the outlook for OPEC and energy prices.
Even though experts say the need for conservation continues, lower energy prices have taken some of the fervor out of corporate efforts to increase energy efficiency. For example, Mr. Yergin notes that a major chemical company recently decided that new energy conservation projects must pay for themselves in nine months. Before, energy saving investments were approved if they paid for themselves in three years. With that change, fewer energy-saving efforts will be undertaken.
Curtailing conservation efforts may prove costly if, as some analysts expect, natural gas supplies tighten. Several things could lead to such a tightening, according to Geoffrey M. Hertel, senior oil analyst at the brokerage firm Rotan Mosle Inc.
Economic recovery will push up demand for gas by about 10 percent, Mr. Hertel contends. At the same time output from certain gas fields in the Gulf of Mexico will decline by 10 percent because of geological factors. The combination will be enough to wipe out the current surplus, he argues.
''We are going to be short of natural gas sometime between 9 and 12 months out, at least, and 21/2 years at most,'' Mr. Hertel says.
The effects on the economy of future price changes in imported energy are likely to be smaller than the oil shocks of 1973-74 and 1979-80, economists note. That is because the US is importing less energy and the economy has grown considerably, so price changes are likely to represent a smaller fraction of the economy.