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Doyon Nenana well not commercial; plans another 3-D seismic survey
The Toghotthele No. 1 exploration well that Doyon Ltd. drilled this summer in the Nenana basin was not a commercial success, Aaron Schutt, Doyon president and CEO, told the Resource Development Council’s annual conference on Nov. 17. However, Doyon remains sufficiently optimistic about finding a viable gas pool, or possibly oil, in the basin to continue its exploration, despite now having drilled three wells in the basin, none of which have discovered a viable hydrocarbon resource.
On Nov. 12 the Doyon board sanctioned a new 64-square-mile 3-D seismic program in the more northerly part of the basin, Schutt said.
“We’re very excited about that,” Schutt said. “We expect to have our data back in late spring of 2017. We’re very hopeful that the results of that will prove interesting enough to drill well number four in the basin.”
The land in the Nenana basin shows much resource potential. And a significant gas find in the basin, which is just 50 miles from Fairbanks, would help solve the issue of supplying affordable, clean energy to the Alaska Interior, Schutt said.
Confidential results Cook Inlet Region Inc. partnered with Doyon for the drilling of the Toghotthele well, with CIRI having a 45 percent interest in the project and Doyon, the operator, having a 55 percent interest. Under a confidentiality agreement with CIRI, Doyon cannot comment on the specifics of the drilling results - according to data published by the Alaska Oil and Gas Conservation Commission the well reached a vertical depth of 11,379 feet.
Schutt told reporters that, although the Toghotthele well was not commercial, the results of the drilling were very encouraging.
“If we had a well where the geology was not encouraging we would not be continuing,” he said.
Schutt also commented that, with the drilling of the Toghotthele well starting on June 1, relatively early in the summer, there had been sufficient time to gather rock samples and associated data from the well. There had not been time to obtain this extent of data from Doyon’s two previous Nenana basin wells, in part because the drilling had started later and in part because of difficulties that had arisen during the drilling. The drilling of the first well was impacted by a nearby forest fire, while the second well ran into drilling complications that required the drilling of a sidetrack.
Gas and oil potential The Nenana basin, on the west side of the Parks Highway, north of the Alaska Range, contains a thick sequence of terrestrial Tertiary strata, including abundant coal seams. Although coal tends to be associated with the production of natural gas rather than oil, Doyon’s previous drilling results and surface soil sampling have found evidence for the existence of both gas and liquid hydrocarbons in the basin. Gravity and magnetic data, in association with seismic data, have indicated that some sections of the basin reach depths where the subsurface temperatures would likely be conducive to oil formation.
The second of Doyon’s Nenana wells, the Nunivak No. 2 well, drilled in 2013, encountered a significant quantity of gas over a vertical interval of about 400 feet. However, the water content of the reservoir rock was too high for commercial gas production. The gas discovered was so-called wet gas, gas containing both methane and natural gas liquids such as propane. This indicates a thermal rather than biogenic source for the hydrocarbons. Thermally generated hydrocarbons could include oil.
Focus shifting to north There are two deep sub-basins in the Nenana basin as a whole, one in the north and one in the south. All three wells that Doyon has drilled to date have been located in a saddle area between the two sub-basins, an area into which oil and gas might have flowed from deeper levels. The recent and planned seismic surveys are focusing on the more northerly of the deep sub-basins.
Doyon has already conducted two 2-D seismic surveys in that more northerly part of the basin, one in 2012 and one earlier this year. James Mery, Doyon’s vice president for lands and natural resources, has told Petroleum News that, while the 2012 survey covered a fairly broad grid, the survey conducted this year filled in detail from the earlier survey. The 3-D survey to be conducted this winter will focus on a promising area where Doyon has identified some exploration leads, with the intention of developing one or more of these leads into specific prospects that could become drilling targets, Mery said.
The region that Doyon is exploring in the basin involves 400,000 acres of state leases, about 40,000 acres of Doyon-owned subsurface and some Mental Health Trust land. This winter’s seismic surveying will involve a combination of state and Doyon land, Mery said.
- ALAN BAILEY
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