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Three contractors plan North Slope geophysical programs
National Petroleum Reserve-Alaska target of two; third is Foothills program for Anadarko Petroleum Kristen Nelson PNA Editor-in-Chief
By Fairweather Geophysical LLC, PGS Onshore Inc. and WesternGeco have all applied to the state for permits for winter North Slope geophysical programs.
WesternGeco plans a two crew program, both two-dimensional and three-dimensional seismic, with 500-1,000 square miles per crew.
Stretching from ANWR to NPR-A The program area is described very generally: from the Arctic National Wildlife Refuge to the National Petroleum Reserve-Alaska, south to Gates of the Arctic National Park and Preserve. Access will be from Franklin Bluffs and/or the Inigok airstrip. The programs would run from as early as Nov. 15 until as late as May 31.
Fairweather plans some 900 square miles of 3-D in two areas, described generally as from Jones Island to Admiralty Bay south to Umiat. The “regional 2000” program, the company said, may be entirely within NPR-A, west of Teshekpuk Lake. The other program, “Colville core 2000,” would be in the Colville River area, mostly within NPR-A but extending into state lands along the Colville.
Estimated dates for the program are from Dec. 26 through May 31.
Neither Fairweather nor WesternGeco lists a client for its programs.
The third program, by PGS Onshore, is in the Brooks Range foothills for Anadarko Petroleum Corp., generally from ANWR to NPR-A south of 5 North Umiat Meridian to the Gates of the Arctic National Park and Preserve, from Dec. 1 through May 31.
PSG said that some 1,000 miles of 2-D and 827 square miles of 3-D are planned, the 3-D in two blocks, one of 452 square miles and the other 375 square miles.
Like WesternGeco's, this is a two-crew program.
Rubber tracks needed in Foothills PGS told the state that it has been addressing problems it encountered in last season's operations, and has “determined that the use of wheeled vehicles in the Foothills area is undesirable.” The company said it found that even when wheeled vehicles were equipped with super-wide tundra tires, “they were unable to traverse the deep snow, gullies and steep slopes without support from tracked vehicles, which caused additional impact and occasional superficial damage to the tundra from spinning the tundra tires.”
PGS said it experimented with a Case/IH Quadtrack during last season, helped design rubber tracks for the vibrators and has “invested a large sum of money” to “build new rubber tracks for the vibrators.”
“We have also changed our mode of operations to incorporate the new equipment,” PGS said. The company's recorder, vib tech unit and cable-geophone carriers “will be mounted on rubber tracked trailers for the 3D crew and sleighs for the 2D crew, which will be towed by the rubber tracked, articulating Quadtracks.”
PGS said cable units, recording and vib tech units and vibrators will be left in the field overnight and personnel carriers will move crew to and from camp. The sleigh-mounted trailers will move four to eight miles each day for the 2-D camp and will be moved every two or three days for the 3-D camp to reduce impact on tundra.
Except for Caterpillars, PGS said, all vehicles are equipped with rubber tracks.
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