State officials working on permits believe about the same number of test wells will be drilled this winter as in the 2007 season, about 8 to 10, but much of the drilling will be by small independent companies drilling smaller targets around the existing infrastructure of the producing oil fields rather than major companies exploring in remote areas.

There will be some remote drilling, mainly near Umiat on the southern North Slope and the White Hills area south of Prudhoe Bay, but in general the industry has pulled back from exploration in unexplored areas of the central and western area National Petroleum Reserve-Alaska after disappointing results in wells drilled in early 2007.

Managers of companies planning wells say the Legislature's recent enactment of a major tax increase on the industry won't greatly effect exploration activities this winter because the companies' plans were too far along by the time lawmakers approved the higher taxes on Nov. 16.

There will be effects on exploration in the 2009 winter season, however. Ken Thompson, managing director of Brooks Range Petroleum, a small company now exploring the North Slope, said the result of the tax changes may be that his company will only be able to do about 75 percent of the work it had planned in 2009.

Meanwhile, two companies active in exploration last season will not be doing work this year mainly because of disappointing results from previous drilling. Pioneer Natural Resources participated in test wells last season but will not do so this year, spokesman Tadd Owens said. FEX LLC, another company that has been an active explorer in the last two years, will not drill this winter either.

Last season ConocoPhillips drilled a test well south of Barrow that was unsuccessful. Farther east near Cape Simpson, FEX LLC drilled and found oil and gas, but the company has chosen not to go back and drill again this year or to test what it has found.

There will likely be some drilling in the NPR-A this year. ConocoPhillips has said it plans at least two wells to further define a series of small discoveries made in earlier drilling. The company has also filed plans with the state to drill “Char 1,” a test well in shallow offshore waters just off the Colville River delta on state leases.

One of the most active explorers this winter will be Brooks Range Petroleum, which is operating for itself and two partners. The company is going back to test and drill one to two new wells around a discovery made last season at the company's North Shore No. 1 well near Gwydyr Bay, north of Prudhoe Bay.

Brooks Range will also drill a test west of the Kuparuk River field near the Colville River that it calls Tofkat.

Thompson said the plan for Brooks Range is to test the North Shore well, drill an additional exploration well at that location and then move the rig to Tofkat.

If that well is successful, a second well will be drilled to delineate the find. If Tofkat isn't a success the rig will be brought back to Gwydyr Bay to drill another well near North Shore, Thompson said.

The discovery made last year on the North Slope isn't big enough to be commercial, Thompson said. However, the seismic work that has been done in the vicinity shows several other promising targets. If other accumulations can be found the combination of all of them might be a commercial project, Thompson said.

Another new well planned this winter is near the offshore Liberty field, which is 5 miles offshore in federally owned waters and has an estimated 100 million to 120 million barrels of recoverable reserves.

Savant, a small independent, plans to build an ice island in shallow water and test for a possible satellite accumulation west of Liberty that could extend into state-owned waters.

State officials say that it is possible that the well may show an extension of the Liberty deposit rather than a separate accumulation.

BP now plans to drill Liberty with long-distance extended-reach production wells from the Endicott field about eight miles west of Liberty.

In the White Hills south of Prudhoe Bay, Chevron plans to operate its first North Slope exploration program since it was operator of a test well in the Arctic National Wildlife Refuge in the early 1980s.

The company has brought a rig to Alaska to do the project, which was used initially to drill new gas wells in Chevron's Happy Valley gas field on the Kenai Peninsula, Chevron's Alaska manager, John Zager, said.

The rig is being moved to the North Slope in December for the White Hills project, Zager said. How quickly the company can mobilize and begin drilling will depend on the winter weather and how soon ice roads can be built in the region.

Other test wells are planned near Umiat, on the southeast border of the NPR-A. Anadarko Petroleum and two partners, BG North American and PetroCanada, plan to drill on lands owned by Arctic Slope Regional Corp.

The primary targets are gas prospects, although finding oil with gas can never be ruled out. It will be the first drilling for gas on the North Slope.

At Umiat itself Renaissance Umiat, an independent company, plans to drill more wells in hopes of expanding and developing the small oil discovery made at Umiat decades ago.

Oil discovered at Umiat was very shallow - some of it in the permafrost - and was light and of a high grade. The early drilling in the area was by the U.S. Navy when NPR-A was a naval petroleum reserve and by the U.S. Geological Survey after the reserve was transferred to the U.S. Department of the Interior in the 1970s.

Another test well to be completed this winter is at Jacob's Ladder southeast of Prudhoe Bay where Anadarko drilled last winter but did not complete the well. Anadarko's partners in the well include BG North America and Arctic Slope Regional Corp.