Sideways oil drilling value examined

BOULDER, Colo., Nov. 14 (UPI) -- Conservationists hope modern, greatly improved directional drilling technologies can reduce the adverse effects of oil exploration activities on surface values such as wildlife habitat -- especially in sensitive locations like the Arctic National Wildlife Refuge.

The Bush administration for some time has been pushing the development the oil resources in the refuge as a means of reducing dependence on imported oil sources, although the idea has been opposed by environmental groups and Congress continues to debate the issue as part of new energy legislation.

Whether or not ANWR is opened to drilling, the oil industry appears to be reluctant to incur additional costs usually entailed by the technologies used solely for environmental protection.

Bill Eustes, professor of petroleum engineering at the Colorado School of Mines in Golden, said directional drilling can cost an additional $10,000 a day more than the usual cost for a vertical well.

John Moran, a petroleum engineer for EnCana Oil and Gas Co., in Denver, said his firm "typically sees an increased well cost of $100,000 (for directional drilling) over a vertical well." That represents about 10 percent of the total cost of the well.

Directional drilling is a technique to drill for oil and gas at an angle into the Earth. New technologies permit drilling from very shallow angles to very sharp ones, and sometimes for long distances. BP Amoco recently drilled a virtually horizontal well from onshore in Britain out into the English Channel for 6.3 miles to recover about 15,000 barrels of oil per day.

Traditional vertical drilling requires close spacing of oil wells -- sometimes one for every 5 acres, with the attendant service roads, pipelines and other disruptions. Under the proper conditions, using directional drilling, several wells can be drilled from the same well pad, disrupting much less of the surface.

Erik Molvar, a biologist with the Biodiversity Conservation Alliance in Laramie, Wyo., said habitat fragmentation for wildlife, from roads and other oilfield-related surface disruptions, is a large and growing problem if the American West.

"Directional drilling allows sensitive habitats to be protected," he said. "It can move impacts away from sensitive habitats. ... Directional drilling should be the primary method of doing business."

So far, though, the industry usually has not used directional drilling for environmental reasons.

"Everything depends on the economics," Eustes told United Press International.

Given the proper characteristics in an oil field, directional drilling can increase the recovery rate for petroleum, but not every field is suitable for the techniques. There also remain substantial technical challenges, despite great strides over the past several decades.

The industry usually is willing to use the techniques on large potential fields, such as BP's horizontal well. In the Rockies, 50 barrels a day from a well is considered pretty good, he said.

"Most of the time, you need many wells to drain reservoirs," Moran told UPI.

He said he has supervised more than 300 S-shaped wells in the Mesa Verde sand formations in western Colorado. Oil usually is not sitting in a big underground pool, he added, but is found in different deep sands formations that are not connected -- a little like potato chips laying in a bag.

"Often you need 64 wells per square mile -- one every 10 acres. Otherwise you miss a lot of pay sands," Moran said. "If you don't drill so densely, you won't drain the field. Some areas required 5 acre spacing."

Directional drilling is best, he said, in mountainous areas, offshore, in urban settings, and for certain homogeneous reservoir types. Yet federal agencies rarely even consider directional drilling as an alternative for oil and gas projects involving federal lands minerals, Molvar said, "and the oil and gas industry frequently balks when asked to use the technologies."

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Dan Whipple covers environmental issues for UPI Science News. E-mail sciencemail@upi.com