"At current rates, our proven reserves alone on the North Slope represent 20 years of production at today's rates, 20 more years of production virtually in the bank, as long as we can make North Slope projects globally competitive for investments," Marshall said. "And we can extend it way beyond that with the unproven reserves we already know we have."

Although the North Slope is a maturing oil province, Marshall said, BP is not pessimistic about Alaska and has no intention of selling its Alaskan operations or of "harvesting" the remaining oil before abandoning the state.

Cutbacks over the past year may have made Alaskans nervous, he acknowledged. "Some of the changes have been painful; many have been misunderstood," he said.

BP last year closed its Alaskan frontier exploration office, transferring executives to Houston. Early this year, the company announced it would lay off 120 of its 600 Anchorage-based employees and 75 of its 100 Anchorage-based contract workers.

Those moves were intended to streamline operations and help ensure BP's future viability in Alaska, Marshall said.

The company can no longer afford to "chase new barrels regardless of cost, and we will only choose projects that will continue to improve our financial performance," he said.

The decision to end exploration in frontier areas came after evaluating past performance, he said.

"Others have succeeded at frontier exploration on the North Slope. We have not," he said.

Instead of seeking new oil in places like the federal National Petroleum Reserve-Alaska on the western North Slope - an area where Arco Alaska Inc. and its Phillips Alaska Inc. have struck new pockets of oil - BP will concentrate on enhancing recovery from existing fields, he said.

In the past 10 years, the company has found and commercialized 160 million barrels in new North Slope territory, compared to the 900 million barrels it has added in reserves at existing fields, he said. "That's where we've been successful, and that's where we're going to focus our effort," he said.

BP's estimate of a remaining 7 billion-barrel North Slope resource assumes no future oil finds, Marshall said. "We're not banking on any future exploration success," he said.

That includes the Arctic National Wildlife Refuge, the area on the eastern North Slope the Bush administration is hoping to open to oil development, Marshall said.