May 15, 1981

''The Tower'' - a musical theater piece by the Pulitzer prizewinning composer Michael Colgrass - will be given its American premiere on Roosevelt Island tonight at 8 by 20 schoolchildren. Roosevelt Island? Schoolchildren? Yes. The musical, a modern, urban version of ''Jack and the Beanstalk,'' was written to be performed by children. Nancy Breth, a pianist who lives on the island, planned and raised funds for the community event. The Canadian composer auditioned and helped in rehearsals. Various professional people, including Diana Baffa Brill, a choreographer who is directing the work, donated their time. The site is the Chapel of the Good Shepherd on Main Street. Tickets are $4 ($2 for children, the elderly and the handicapped). Information: 753-6889 or 371-4642. UKRAINIAN 7TH ST. FESTIVAL Seventh Street, between Second and Third Avenues, will be closed to traffic and open to celebrants today, tomorrow and Sunday for the fifth annual festival sponsored by the St. George Ukrainian Catholic Church. Ukrainian dancers and singers will perform. Ethnic foods - pierogi, kolbasa, stuffed cabbage and home-baked pastries -will be available. So will crafts, including embroideries, wood carvings, ceramics and Easter eggs. And booths will offer games of chance. Hours: 4 to 11 P.M. today, 11 A.M. to 11 P.M. tomorrow and 1 to 10 P.M. on Sunday.

The United States petroleum industry is fast reaching a consensus that crude oil is too expensive, and a dozen oil companies have reduced the price they will pay for a barrel of domestically produced oil by an average of $2 a barrel. Conoco Inc. announced yesterday that it was cutting its posted buying price for crude by $2 in most parts of the United States, effective today. And so far this week, Texaco, the Sun Company, Ashland Oil, Standard of Ohio, Husky Oil, Marathon, Pennzoil and Dorchester Gas have cut their prices by an average $2 a barrel, to a range of $34 to $36 in most cases. These reductions follow similar moves last week by Cities Service, Phillips Petroleum and Standard of Indiana. Other companies are considering similar actions. For example, Atlantic Richfield said yesterday, ''We are reviewing our position. However, we have not made a decision as yet.'' Shell Oil said it was ''constantly'' reevaluating its posted prices.

The cargo freighter Atra is a troubled ship. Her hold is full of unsold scrap metal, her fuel tanks and food lockers are almost empty and her bridge is plastered with liens from creditors, including her crew, which has not been paid since March. The saga of the Atra, now at a berth on Staten Island, has led the freighter since the turn of the year from New Brunswick, Canada, to New Haven - where a ''rampage'' by a previous crew all but disabled her - and finally to New York. She has been detained at Staten Island since mid-February, first by the Coast Guard and then by legal action from her creditors.

A news analysis May 7 on the Inter- national Brotherhood of Teamsters in- correctly characterized the state of health of Jackie Presser, a vice presi- dent of the union. Mr. Presser is in good health.

An operation financed by four insurance companies has led to four arrests and the recovery of more than $200,000 in stolen gold and silver jewelry, guns, electronic equipment and other valuables, Connecticut's Attorney General said today. The ''sting on a shoestring,'' as the Attorney General, Francis M. McDonald, called it, also led to the issuance of warrants for the arrest of 20 other persons. The undercover operation was financed through the Insurance Crime Prevention Institute, with contributions of $5,000 each from the Travelers Insurance Companies, the Connecticut General Insurance Company, the Hartford Insurance Company and Aetna Life and Casualty.