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F&W assesses Apache seismic survey plan Agency has published draft environmental assessment for proposal to conduct a 3-D seismic program in the northern Kenai Peninsula Alan Bailey Petroleum News
As part of a major program of 3-D seismic surveying in Alaska’s Cook Inlet basin, Apache Alaska plans to conduct an on-land survey in about 142,000 acres of the northern Kenai Peninsula, where the company wants to seek exploration drilling targets in subsurface land owned by Cook Inlet Region Inc., the Native regional corporation for Southcentral Alaska. Apache is aggressively searching for as-yet-undiscovered oil and gas resources in the Cook Inlet basin and has said that it views the acquisition of modern, high-resolution 3-D seismic data as an essential prerequisite to exploration drilling in the basin’s challenging geology.
Special use permit The Kenai Peninsula land lies within the perimeter of the Kenai National Wildlife Refuge, administered by the U.S. Fish and Wildlife Service. Consequently, Apache has had to apply for a special use permit from Fish and Wildlife to enable the company to conduct the surface operations required for the survey. Under the terms of the U.S. National Environmental Policy Act Apache’s permit application triggered an environmental assessment that will lead to a decision by Fish and Wildlife as to whether the proposed survey would have a significant environmental impact. And that decision will in turn determine whether the agency can immediately issue a permit, or whether further environmental review is necessary.
In April Fish and Wildlife issued a draft environmental assessment for the planned survey, with public comments on the draft document required by May 31.
Two phases According to the environmental assessment Apache anticipates conducting the survey operations in two phases: one in the winter of 2013-14 and the other in the winter of 2014-15. The company plans to use a survey technique in which each seismic recorder works within its own sealed node, each node independently recording the sound signals from the seismic sound source while using global positioning system technology and satellite-based timing to accurately position and time the recording. This technique, which Apache has successfully used in a survey on the west side of Cook Inlet, minimizes environmental disturbance by eliminating the need to cut seismic lines through surface vegetation for the laying of cable. A seismic crew carries the seismic nodes, each about the size of a large food can, into position by backpack.
Only approved snow machines will be allowed for off-road surface transportation within the refuge, the environmental assessment says.
The source of the seismic sound signals will be explosive charges, set at depths of up to 35 feet in shallow drill holes that are back filled to minimize any ground disturbance. Apache will use a small drilling unit, slung under a helicopter for carriage to drill sites, to drill the shot holes, the assessment says.
20,000-foot depth With a target depth of about 20,000 feet for the base of its required 3-D seismic images, Apache plans an approximately 40,000-foot square grid of receivers for each seismic shot. Recorders will be placed at 165-foot intervals along parallel lines one-quarter mile apart, with a total of 4,368 recording nodes required for each shot, the assessment says.
Starting near the coast, on the west side of the survey area, the seismic crew will progressively move east, transferring the receivers on the westerly trailing edge of the survey grid to the eastern leading edge after each shot, the environmental assessment says.
The Alaska National Interest Lands Conservation Act, the 1980 federal statute that established the Kenai National Wildlife Refuge, includes provisions that allow access to privately owned land within the refuge for economic or other purposes, provided that this access does not violate regulations designed to protect specified refuge values, the assessment says.
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