A new and promising frontier for world oil production, potentially larger than the Alaskan and North Sea Fields combined, is being developed with financial help from the World Bank.

The frontier lies in roughly 50 of the world's poorer countries, the underdeveloped nations of Africa, Latin America and Asia, which were long neglected as potential sources for new oil but are now regarded as rich in possibilities.

World Bank officials yesterday announced details of a broad program of lending and technical assistance of up to $500 million a year, intended to help 50 and 60 oil-importing nations become self-sufficient oil producers in the next decade.

This would greatly ease the financial strains on those nations, which now import as much as 80 percent of their oil at the $13-a-barrel cartel prices. Those countries suffered most when oil prices soared five years ago.

But Third World oil development should also benefit Western industrial nations, like the United States, by easing some of the pressure for increased production and higher prices on Saudi Arabia and other organization of Petroleum exporting Countries cartel.

According to the World Bank's "cautious" projections, the less-developed countries are expected to increased their oil production levels from 3.8 million barrels a day to 8.5 million by 1985 and 10.4 million in 1990.

At present, these nations together import about 2 million barrels daily from OPEC producers. By 1990, they are expected to be net exporters, taking care of their own growth in oil consumption and selling 1.5 million to 2 million barrels to the rest of the world.

So far, the bank has made one loan of $150 million to India for the development of an offshore field. By the end of next year, it hopes to have eight projects under way totaling $500 million, which will be "seed" financing to generate $3 billion to $4 billion in other investment capital.

Bank-assisted projects are under discussion in Bangladesh, Pakistan, Turkey, Thailand, Syria, Tunisia, Egypt, Zaire, Argentina, Columbia, Chad and Bolivia, among others.

"In five years," said Efrain Friedmann, energy expert at the World Bank, "we will be doing twice what we did in the last 30 years."

The new trend rests upon two premises. The high world price engineered by OPEC now makes it possible, even mandatory, for smaller nations to develop less promising exploration areas. And according to recent studies, these areas in under-developed countries have a potential for new oil two or three times greater than the conventional wisdom has long predicted.

"These things turn around so fast," Friedmann said. The estimates and projections of potential new oil, he added, have historically proven to be "unbalanced on the conservative side."

Mexico is currently the world's startling example of this phenomenon. A few years ago, Mexico was importing oil; now it is developing production and will enter the ranks of major exporters - more than 2.5 million barrels a day - within a decade.

In the pre-OPEC past, as the World Bank experts explain it, there was little or no incentive for either major oil companies or individual nations to develop their domestic oil and gas. Oil cost $ a barrel and the major multinational companies spent less than 7 percent of their exploration capital in the non-OPEC developing nations.

The major companies were discouraged from exploration - elsewhere by political instabilities or nationalistic hostilities. Some nations were content to develop their own fields slowly and exclude the international companies. Since 1973, that has changed in nations such as Brazil, Argentina, Chile and Colombia.

The World Bank portrays its role in these arrangements as "honest broker" - reassuring the corporations of political stability and helping the poor nations to assemble the financing from various international lending organizations and private envestment.

In some instances, the oil fields will be too small to interest the multinational giants. In those cases, the World Bank hopes to provide the technical assistance which would help national oil companies to develop their own resources.

Many of the more promising geological areas are in countries that lack the technological expertise to develop their own resources and therefore, should be more attractive to the international companies. These include Bangladesh, Guatemala, Nicaragua, the Philippines, Thailand, Vietnam and most countries on the West Coast of Africa.

The World Bank's policy is based in part on a global study by Bernardo F. Grossling of the U.S. Geological Survey, who concluded that the potential for oil discoveries in the less-developed nations is two or three times greater than the pessimistic estimates of conventional reserve figures.

Grossling determined that the main reason not much oil has been found in those countries is that relatively little drilling has been done on those continents over the years. In Africa's 5 million square miles of prospective areas, only 12,850 wells had been drilled by 1975 - compared with 2.4 million wells drilled in the United States.

The traditional explanation for the lack of drilling activity in underdeveloped countries included the claim that past explorations yielded poor results. But Grossling's study discovered that the reverse was true. Over the years, more oil was discovered per foot of drilling in Africa and Latin America than in the United States or Western Europe.

Based on his calculations of drilling and potential discovery areas, Grossling concluded that the developing countries represent about half of the world's prospective areas but only about 4 percent of the world's exploratory drilling has taken place in those countries.

None of the experts claim that another Middle East, which has 45 giant fields, awaits to be discovered somewhere in the world. But Grossling predicts that Africa, Latin America and Asia each has three to eight giant fields yet to be found.