Treasury Secretary W. Michael Blumenthal opened Soviet-American trade talks today in which the United States announced approval of export licenses for $54 million worth of oil and gas exploration equipment sought by the Krem-lin.

As the Soviets were smiling over this, however, Blumenthal sharply rebuked their handling of American businessman Francis J. Crawford, who was dragged from his car last June by Moscow police, jailed, then convicted of black market money operations.

"The affair has had a significantly detrimental effect on American public opinion and in our economic relations," Blumenthal declared. "The violence employed against Crawford and his fiancee was quite inappropriate to the circumstances and the offenses."

Blumenthal said Crawford's incarceration for about two weeks and the harassment and intensive interrogation to which he was subjected even after his conditional release were profoundly disturbing to the American business community. "We trust this unfortunate occurrence will prove to be an isolated incident," he said.

Crawford was eventually allowed to leave Moscow.

First Deputy Foreign Trade Minister Mikhail Kuzmin, head of the Soviet delegation, had no reply to Blumenthal on the Crawford case, widely believed by the American community here to have been created by the Soviets as a possible counter to espionage cases against two Soviet diplomats in the United States.

Kuzmin is leading the Soviet side in the two days of talks in the absence of Foreign Trade Minister Nikolai Patolichev, who is officially said to be ill. Kuzmin blamed U.S. discrimination for the downturn in Soviet-American trade from the high point of 1976.

Referring to President Carter's summer decision to cancel a computer sale to Tass, the Soviet press agency, Kuzmin called it a "strengthening of discrimination" by the administration. "Those who take this approach have a false estimate of the state and possibilities of the Soviet economy," Kuzmin added, saying Moscow could develop its economy without U.S. trade.

Soviet officials assert that U.S. trade this year will amount to two hundredths of one percent of the Soviet gross national product. They deeply resent the 1974 Trade Act and Jackson-Vanik amendment, which tie U.S. trade credits to Soviet emigration policies.

U.S.-Soviet trade has been in the doldrums in recent years because of the congressional restriction and because of Soviet shortage of hard currency and failure to use existing Western credits.According to figures for the first eight months of this year, U.S.-Soviet trade turnover amounted to $2.2 billion, up 60 percent from the 1977 period, but only because of heavy Soviet grain purchases.

Nonagricultural turnover actually will decline this year from last, Blumenthal said, and be "much less" than the 1976 peak. He said the administration, "in consultation with Congress, wishes to further expand trade" with the U.S.S.R.

From 1962, when there was one U.S. company permanently based here, the number has grown to about 30, but business has never achieved the volume envisaged eight years ago, at the beginning of detente.

The oilfield projects approved today include an offshore drill rig, pumps and electronic equipment manufactured by such firms as IBM, Caterpillar, Brown and Root, and Control Data Corp. Delegation sources said the United States has approved licenses for $270 million this year in oilfield technology equipment and projects the Soviets want.