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DGGS-led team to investigate Nenana basin State geological survey collating available data about the basin and planning fieldwork to the north of the Alaska Range this summer Alan Bailey Petroleum News
Alaska’s Division of Geological and Geophysical Surveys is starting an investigation of the oil and gas potential of the Nenana basin, in Alaska’s interior, about 50 miles southwest of Fairbanks, DGGS geologist Dave LePain told Petroleum News on Jan. 24. The DGGS-led research project is being funded from a state grant and involves scientists from DGGS, Alaska’s Division of Oil and Gas, the U.S. Geological Survey and from Purdue University.
Planning stage The team has started assembling publicly available data for the basin and is planning a 10- to 14-day field season, probably starting in May, LePain said.
“We’re just now … in the planning and data compilation stage,” he said.
The project comes as part of a multiyear program in which DGGS is investigating the energy resource potential, particularly for gas, of several Alaska basins that could perhaps supply energy for rural communities as well as major population centers. In the past couple of years the division has been investigating the Susitna basin, the large sedimentary basin in the Susitna Valley, to the north of Anchorage.
The Nenana basin, lying immediately west of the Parks Highway and Alaska Railroad, the primary transportation links between Anchorage and Fairbanks, is particularly conveniently located for energy development, should the basin contain commercial quantities of oil or gas. Thought to have formed from the pulling apart of the Earth’s crust as a consequence of movements along a major system of geologic faults, the basin is known to contain many thousands of feet of sediments deposited from ancient rivers and lakes. An abundance of coal seams would provide a ready source of natural gas, and possibly oil.
Doyon exploration A private partnership headed by Doyon Ltd., the Native regional corporation for the Alaska interior, has already been conducting a multiyear investigation of the petroleum resources of the basin, mostly in state lands under the terms of a state exploration license. Several years ago that partnership conducted a seismic survey in the southern part of the basin. The partnership drilled the 11,000-foot Nunivak No. 1 gas exploration well, immediately west of the town of Nenana, in 2009 but that well did not encounter an economic gas accumulation.
The Doyon-led partnership is gathering seismic data from the more northerly part of the basin this winter.
A paper published in January in the Oil and Gas Journal, describing some of the findings to date from the Doyon-led program, indicated that rocks encountered by the Nunivak well at depths of just over 10,000 feet had probably reached temperatures approaching those conducive to oil generation. And with gravity data for the basin indicating a maximum basin depth of up to 30,000 feet, coupled with the discovery of coal capable of oil generation, the basin does appear to have oil potential — there is the possibility that more than 8 billion barrels of oil could have been generated in the basin, the Oil and Gas Journal paper says.
New investigation The DGGS team plans to supplement the work of the Doyon project, which was primarily focused on the subsurface, through an investigation of surface exposed rock in the basin, and by tying the results of that investigation into the publicly available gravity and well data. The results of the investigation will themselves become publicly available, for use by anyone interested in the basin’s history and petroleum geology.
With most of the bedrock in the flatlands of the basin obscured by muskeg, swamps and lakes, this year’s DGGS fieldwork will take place in the uplands on the southern edge of the basin, immediately north of the Alaska Range, where there are good rock exposures, Le Pain said. The team will access remote sites by helicopter from Fairbanks.
Collating data Meantime, DGGS is collating all publicly available subsurface data for the basin and is also seeking access to some privately held data, including some seismic data, gathered as part of an industry exploration program that predated the current Doyon-led program. And Alaska Department of Natural Resources scientists have already logged some core samples from one of two exploration wells drilled during that earlier phase of exploration.
Having taken a fresh look at the surface geology and available subsurface data, the team will tie all of this data together, to take a fresh look at the basin history and contribute to a general understanding of the basin’s petroleum potential, Le Pain said.
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