There's no end to Mexican oil boom -- will it reach the poor?

Get ready to move aside, Saudi Arabia, you may soon be overtaken by Mexico.

That possibility is seeming less far-fetched as Mexico's subsoil and offshore waters yield more and more oil.

At the moment, Mexico's proven reserves, about 72 billion barrels, put Mexico in second place among world oil powers. But no one here expects that tally to stand for long. As these words are written, there are fresh indications that during 1982 Mexico will announce proven reserves of nearly 100 billion barrels.

Such a tally is within catch-up distance of Saudi Arabia's proven reserves of 165 billion barrels. The Saudi total is based on exploration of most of its territory. Mexico's, on the other hand, is based on exploration of but 10 percent of its territory.

Indeed, Mexican oil exploration ''has really only begun,'' says Jorge Diaz Serrano, former director of Petroleos Mexicanos (PEMEX), the state oil enterprise. ''At the moment there is no end in sight to Mexico's search for oil.''

Foreign observers here say that PEMEX is essentially conservative in its estimates of reserve totals. Furthermore, it tends to be slow to report new finds. The 72-billion-barrel figure, issued late last year, was probably behind the actual total.

Meanwhile, the Mexican economy is becoming more and more closely tied to oil.

Here in Coatzacoalcos, on the edge of Mexico's southern oil fields, the huge rigs that dot the landscape are constant reminders of oil's importance.

The mood in this once quiet village, now a thriving town, is upbeat.

''The sun is made of oil!'' exclaims Felipe Bastidas Mateos, an oil worker here, as he walks home under a blazing tropical sun after a hard day on the pipeline. ''Oh, sure, the sun isn't made of oil, but we have never had it so good, and I guess you can excuse us for being so excited about oil prospects.

''I'm making more money in a year than my father, who was a farmer, made in his lifetime.''

His salary of some $5,000 a year puts him among the elite of Mexican salaried workers.

What Felipe and others here do not realize and what even some government officials fail to understand are the distortions that oil has brought to the Mexican economy.

Everything in Mexico suddenly depends on the oil and gas extracted from the Reforma fields just to the south of here and from the offshore rigs in the Bay of Campeche.

Yet it wasn't so a decade ago. Mexico imported oil then - about 100,000 barrels daily. It now exports 1.5 million barrels daily.

This transformation has propelled Mexico into prominence not only as a neighbor of the United States and as a Western Hemisphere nation, but as an economic power of consequence on the world stage.

''It is a rather heady experience,'' admits President Jose Lopez Portillo, whose six-year term has more or less coincided with the boom.

Oil has fueled an industrial expansion. New plants have been set up all over Mexico. More than $11 billion was invested from public and private sources in 1981 in new and expanded plant. And an investment of $14 billion is programmed for 1982.

But oil has not been the panacea that many expected. Maybe those expectations were too high. Perhaps the many economic problems facing Mexico's 78 million people are simply too large to be solved in a mere decade. The inadequacies of the transport system, for example, are more apparent every day.

Moreover, the oil boom has yet to solve the inequities that have long plagued Mexican society. It may never solve them. Half of the country's 78 million people live outside the money economy or on its fringes.

Can oil change that? Can oil bring about the transformation needed? These and other questions are uppermost here. So far they are not being answered.