Oil and gas industry analysts understand United States Steel Corp.'s desire to purchase Dallas-based Texas Oil & Gas Corp.

Spokesmen for the two companies had announced last Friday that they are holding talks that could lead to a merger or a joint venture.

The little gas producer has been a regular moneymaker since 1958, when, operating under its original name of Tex-Star Oil & Gas Corp., it reported its first annual profit, $158,204 on sales of $1 million.

What is now Texas Oil & Gas was three years old then, an upstart, low-cost provider of natural gas running on leases acquired in South Texas. But the company's profits rose steadily, reaching $141.1 million in 1980 on its 25th anniversary. That same year, sales exceeded $1 billion for the first time in Texas Oil & Gas' history.

The company continued to do well even when the industry began to slump under the weight of excess capacity and falling prices. Texas Oil & Gas earned $346.2 million ($1.65 a share) on sales of $2.1 billion in its 1984 fiscal year. According to preliminary figures for the 1985 fiscal year, which ended Aug. 31, the company will earn $277 million ($1.32) on sales of $1.7 billion.

Texas Oil & Gas's success is primarily attributable to its conservative, but savvy, management, said Robert E. Phaneuf, a oil and gas industry analyst with Kidder, Peabody Co. Inc.

Texas Oil & Gas stuck to what it knew how to do best -- drill for, gather and produce natural gas. When the drills were not working for Texas Oil & Gas, the company used the equipment and its personnel to drill wells for other companies in the natural gas business. The result was profit in what amounted to helping the competition.

The company has been doing so well that, "to me, there doesn't seem to be any particular reason for management to sell" to U.S. Steel, Phaneuf said. "The only reason I could see why they would want to sell would be to capitalize on their good position."

But the story is different for U.S. Steel, the nation's biggest steel maker, which has been diversifying out of the troubled steel industry since 1981, when it spent $6.5 billion to acquire Marathon Oil Co. The acquisition of Texas Oil & Gas would help U.S. Steel's diversification effort. But, in this case, it is a seller's market. As a result, Texas Oil & Gas can be expected to demand a premium price, perhaps nearly $6 billion, Phaneuf estimated.

Should they be willing to pay the price, U.S. Steel officials will get a company that does most of its business in five states, Arkansas, Kansas, Louisiana, Oklahoma and Texas; a company that last year ranked 14th in terms of U.S. natural gas production with 177.2 billion cubic feet of product, and a company that has natural gas reserves of 1,640 billion cubic feet -- all onshore.

Texas Oil & Gas ranks 33rd in its industry in terms of assets ($3.44 billion) and 43rd in terms of 1984 sales ($2.1 billion). The company also comes with 3,665 employes and outstanding debts totaling $700 million.