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Swanson River gas satellites a go; Chevron, Marathon moving ahead
Both Chevron and Marathon are moving ahead on work at Swanson River satellites where they hope to find commercial quantities of natural gas.
This is an area where gas has been known since the 1960s, with a well drilled in 1965 at the north satellite, Birch Hill, and in 1970 at the east satellite, Sunrise.
An environmental impact statement approving roads to the satellites and expanded and new pad development was finalized in 2004 for the North Swanson River and East Swanson River satellites, both in the Kenai National Wildlife Refuge. A record of decision signed by officials of refuge manager U.S. Fish and Wildlife Service in 2004 and 2005 granted rights of way to Union Oil Company of California and Marathon Oil Co. for development of the Swanson River satellites natural gas exploration and development project.
The North Swanson River satellite — the existing Birch Hill unit northeast of Swanson River, operated by Chevron subsidiary Unocal — has existed since the 1960s. A single well, drilled in 1965, produced 65 million cubic feet of gas over a 12-day test period according to Alaska Oil and Gas Conservation Records. That well is suspended.
In the area of the proposed eastern satellite, on acreage leased by Marathon from Cook Inlet Region Inc., a well was drilled by Forest Oil in 1970 and plugged and abandoned. AOGCC records show that the well, Sunrise Lake Unit 1, had gas shows in the Tyonek formation below 11,000 feet.
Unocal originally applied Fish and Wildlife said the 2001 application for roads and pads was from Unocal, which would have been the operator at both the north and east Swanson River satellites. In 2003 Unocal told the agency that Marathon would be the operator for the eastern satellite. At that time Unocal also requested that processing of its applications for the north satellite — Birch Hill — be suspended.
Marathon applied for a right of way to develop the east satellite in 2003. Coal, oil and natural gas resources in the east satellite have been conveyed to CIRI as part of its entitlement under the Alaska Native Claims Settlement Act with surface and remaining subsurface lands in the east satellite owned by the United States and managed by Fish and Wildlife.
Natural gas resources targeted at the north satellite — Birch Hill — are leased from the federal government. Surface lands at Birth Hill have been conveyed to the Tyonek Native Corp.
Chevron drilled Birch Hill The Birch Hill Unit 22-25 well was drilled in 1965 by original unit operator Chevron — at that time called Standard Oil Company of California. Based on drilling results from the well the company proposed a 940-acre participating area in sections 23, 24, 25, 26 and 36 of township 9 north, range 9 west, Seward Meridian. The well was tested from perforations from 8,190 feet to 8,220 feet, producing an open flow potential of 17.5 million cubic feet a day and a stabilized flow rate of 6.2 million cubic feet per day of dry gas.
The state certified the BHU 22-25 well as capable of producing in paying quantities.
Chevron told the U.S. Geological Survey at the time that the Birch Hill “gas accumulation is controlled by faulting on the western and southern flanks and by a gas-water contact on the northern and eastern flanks.” The well penetrated the pay sand from 8,190 feet to 8,222 feet. “The entire interval was gas productive with no gas-water contact present.”
Drilling continued to 15,500 feet and the well was then plugged back to 8,810 feet and completed through perforations from 8,190 feet to 8,220 feet.
At the time the well was drilled Birch Hill was owned 50-50 by Standard Oil Company of California and the Atlantic Refining Co. which merged with Richfield to become ARCO.
Birch Hill plans In its 44th plan of development and operations for Birch Hill, covering Dec. 14, 2008, to Dec. 14, 2009, Chevron said that while no drilling or remedial work had been conducted in the previous, 43rd plan of development, the company had “continued its technical and risk assessment work as part of the phased diagnostics and remedial wellwork approach to tie Birch Hill 22-25 into production facilities.”
The company said that on an ongoing basis it was focused on maintaining the well’s mechanical integrity, and said it “believes additional work must be completed to safely move toward tying in the well,” and said it “does not intend to disrupt or potentially disrupt the mechanical integrity of the Birch Hill 25-22 well without adequate location access and a detailed emergency response plan specific to the well.”
Chevron said it plans to complete initial onsite well inspections during the 44th plan, and to conduct wireline-pressure diagnostics and flow test the Birch Hill 22-25 well during the 2009-10 winter season.
If the well is commercial, typing it into production facilities would most likely occur in 2010.
Permitting efforts, including surveying the preferred right of way for the gravel road identified in the EIS, were initiated under the 43rd plan of development, the company said. Subject to completion of permitting, vegetation clearing and road construction would occur in the fall-winter of 2009 and Birch Hill 22-25 well testing in the winter-spring of 2009-10.
Well planned at Sunrise CIRI, the resource owner at the east Swanson River satellite, told legislators in June that Marathon has been evaluating the prospect at Sunrise for several years and has shot 2-D seismic survey.
Marathon spokeswoman Lee Warren told Petroleum News in a July 15 e-mail that the company is “continuing to progress our efforts at Sunrise” and is currently planning to drill a well this winter.
Fish and Wildlife said that if full development occurred at the east satellite potential facilities would include some 7.4 miles of new gravel access road, up to 9.7 miles of new buried pipelines and utilities and two pads totaling 6.75 acres.
Full-scale development of the north satellite, Birch Hill, would include some 3.4 miles of new gravel access roads, 5.3 miles of new buried pipelines and utilities and two drill pads totaling 5.5 acres.
The agency said that development of the satellite projects would also require use of some existing facilities, existing roads and existing or new pipelines within the Swanson River field.
—Kristen Nelson
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