A blown-out offshore well that produced the world's worst oil spill -- a total loss equivalent to about one-fifth of the daily U.S. petroleum consumption -- has been brought under control and may be capped within two weeks, according to Mexican officials.

The well, which has poured more than a hundred million gallons of crude oil into the Gulf of Mexico since it blew out June 3, was covered this week with a 310-ton steel cone that has reduced leakage to 1,500 barrels a day -- about 15 percent at the previous flow.

Technichians are drilling two relief wells and their completion, expected within two weeks, should make it possible to cap the well completely and halt the world's worst oil disaster, officials said here yesterday.

The environmental damage caused by the vast flow of crude oil into the Gulf of Mexico and onto Texas coastal areas, however, will probably not be fully known for years. Already suits totaling $350 million have been filed by Texas groups seeking compensation for losses, and the state of Texas is considering filing a claim against the Mexican government.

After months of frustrating failures and setbacks caused by unusually bad weather, the final step began Tuesday in controlling the blown-out Ixtoc I oil well 50 miles offshore in Campeche Bay, one of mexico's richest oil fields.

Shortly before noon, Mexican and U.S. workers on a platform above the choppy water started turning valves. Down below, the 10-foot-high flames from the burning gas shrank instantly and the heaving surface mixture of seawater and petroleum calmed dramatically.

Simultaneously, at a pipe on a platiform above, a gas pilot ignited a flame that shot into the sky and the pipe began to belch up a brown mass of water mixed with oil.

To the hundreds of people who have been fighting the runaway well, this meant one thing: the new device, a funnel of steel placed over the smashed wellhead, had started doing its job and most of the escaping gas and oil was being piped, under control, onto a processing platform and not spilling into the sea.

With that, oil technicians say, the world's largest oil spill is as good as tamed.

The spill so far is greater than the estimated 2 million barrels of petroleum lost in the collision of two supertankers near Trinidad in July and is twice that resulting from the breakup of the Amoco Cadiz off France in March 1978.

The disaster already has cost Mexico close to $150 million in cleanup and salvage operations and lost curde and gas. It also has produced a great deal of domestic political difficulty for pemex, the Mexican state oil company, and diplomatic sparring between Mexico and the United States over damage claims.

Although the immediately apparent injury to the southern Texas coast is less than had been feared, suits seeking damages of $350 million have been filed by shrimpers and fishermen as well as property owners and people in the tourist business.

Citing damage to the economy and environment, Texas also has filed a $10 million suit, Texas Attorney General Mark White told a news conference in Austin today.

Defendants in the suits are SEDOCO, Inc., the company founded by Texas Gov. William Clements and run by his son, Gil. SEDCO supplied the oil rig that blew out. Another defendant is Permargo, the private Mexican drilling contractor hired by Pemex.

Mark White, a Democrat locked in political battle with Republican Gov. Clements about whether Mexico should be sued for cleanup costs, told the news conference in Austin today that there would be no legal action taken at this time against Pemex.

"we are refraining from doing so until it is certain that all negotiations by the U.S. Department of State for damages from Mexico in regard to the oil spill have been exhausted," said White.

A lucky combination of changes in wind direction, hurricanes and seasonal current changes turned back the worst masses of floating crude oil "just as it was moving toward catastrophic proportions" in Texas, Jack Woody, southwest regional chief of the U.S. Fish and Wildlife Service's endangered species section said in Albuquerque.

Woody and others monitoring the effects of the spill emphasize that it will be a year or longer before long-term damage becomes apparent. Vast slicks of the spilled crude are still offshore and wind and current changes in February could bring them to the Texas coast again. Woody said.

Mexico's president Jose Lopez-portillo has adamantly refused to discuss any financial compensation on the principle that past Mexican claims for damages caused by various forms of u.s. pollution were not recognized by the United States.

Experts have agree that the disaster was largely a case of a combination of freak accidents topped by failure of the blow-out preventer, a huge explosion and a fire that destroyed the drilling platform. As the platform collapsed onto the sea floor, it further smashed the well-head.

As official verdict of the Mexican attorney general has cleared all individuals, both Mexican and American, working with the drilling rig of any blame.

The device implanted this week, designed by Brown and Root of Houston, is seen as a valuable new tool to cope with future offshore drilling accidents. i

Although "collecting funnels" have been tried on other blow-outs, this is the first of its kind to show success in the open sea.

The octagonal steel cone is almost 40 feet in diameter. It hinges from a boom attached to a tower that stands on the ocean floor and the cone sits like a funnel over the well.

Pressure from the well forces oil and gas upward into a pipe that leads to separators on the platform above. Here, a pilot burns off the gas, the water is thrown back into the sea and the crude runs to a second platform where it is dumped into barges.

"We have captured more than 80 percent of the flow," Pemex President Jorge Diaz Derrano told reporters following the successful maneuver Tuesday.