Major oil find could boost US reserves by half

One of the world's biggest oil companies held out the prospect that the US could increase its domestic oil reserves by up to a half after unveiling positive results from drilling in the Gulf of Mexico yesterday.

Chevron said it had made significant progress in its exploration of a new oilfield deep below the seabed, 270 miles south-west of New Orleans.

Industry analysts believe that the field could contain up to 15 billion barrels of oil and may overtake BP's troubled Prudhoe Bay field in Alaska as the country's largest.

If Chevron and others can overcome the technical difficulties in extracting oil, it could also significantly lessen US dependence on foreign oil, and reduce political pressure to open up the environmentally sensitive areas of Alaska.

President George Bush has long emphasised the need for the US to reduce its dependence on oil from troublespots such as the Middle East, one of the reasons he has supported an end to the ban on further exploration in the Alaskan national wildlife reserve.

But finding new domestic sources of oil has proved difficult for the US oil companies. Chevron's work on its Jack field in the Gulf of Mexico was among the most complicated exploration work undertaken by an oil major, setting several records for test equipment pressure, duration and depth. The experimental well was drilled to 28,000 feet under the sea floor.

George Kirkland, executive vice-president, upstream and gas, said: "Chevron continues to demonstrate its leading position employing deep-water exploration technology to develop new supplies of US crude oil and natural gas with projects such as Jack. Our strong strategic position in the deep-water Gulf of Mexico will continue to be a platform for future growth for years to come."

The high price of oil has made more complex drilling work economical. Jack and its connected properties - which have been parcelled out among oil majors including UK groups BP and Royal Dutch Shell - could have between 3 billion and 15 billion barrels of recoverable reserves. The US currently has reserves of 29 billion barrels.