Ahtna Inc., the Native regional corporation for the Copper River region, has filed a plan of operations for the proposed drilling of a gas exploration well in state land north of milepost 175 of the Glenn Highway, about 11.5 miles west of the town of Glennallen.
The plan, filed with Alaska’s Division of Oil and Gas, says that the proposed well, the Tolsona No. 1, will target thick Nelchina sandstone intervals at depths between about 4,000 and 5,000 feet. A diagram accompanying the plan indicates the possibility of testing gas in two distinct intervals, the upper Nelchina and the lower Nelchina.
The well location is section 23, township 4 north, range 4 west of the Copper River meridian.
Exploration license
Ahtna is conducting its exploration under the terms of a state exploration license for the Tolsona area. In 2014 the corporation acquired more than 40 line miles of new seismic data and processed more than 80 miles of existing data for the license region, before deciding on an exploration drilling site.
A previous gas exploration well, the Ahtna 1-19 well, drilled by Rutter and Wilbanks between 2005 and 2007 at a location about two miles east of the proposed Tolsona well, encountered gas but was eventually abandoned because of exceptionally high formation pressures and problems with water encroachment.
Ahtna is contracting with HXR Drilling Services to drill the Tolsona well, possibly using the Saxon 147 drilling rig, Ahtna’s plan of operations says.
The primary purpose of Ahtna’s gas exploration program is to find a gas supply for local use in the Copper River region, to alleviate the high cost of energy in the region. In the immediate future, the drilling project will bring a number of local jobs, the corporation says.
Small gravel pad
Drilling of the Tolsona well will take place from an approximately four acre gravel pad about a mile north of the Glenn Highway and to be connected to the highway by a gravel road. To minimize the size of the new pad, Ahtna plans to use the old Ahtna 1-19 pad as a staging area. After completion of drilling operations and any subsequent gas-field-related usage, the new road and pad could be used for recreational access to state land in the Tolsona area, Ahtna says.
According to its operations plan, Ahtna anticipates constructing the Tolsona gravel pad and access road between early January and mid-February. Following the mobilization of equipment, drilling should take place between mid-March and mid-April, with the well being completed by late April and well testing taking place in late April and early May. Demobilization and site cleanup should be complete by the end of June, Ahtna’s plan says.
Ahtna says that, because of a forecasted mild and short winter, and because of a lack of an adequate local water supply, it had discounted the possibility of drilling in the winter, using ice-road access to an ice drilling pad.
Permits needed
Ahtna will need to obtain a U.S. Army Corps of Engineers Section 404 dredge and fill permit, and easement permits from the Alaska Department of Natural Resources, before the drilling project can be conducted.
The Copper River basin in which Ahtna plans to drill has similar geology to the prolific Cook Inlet basin but has seen very little exploration. Although the Mesozoic rock unit that sources oil in the Cook Inlet region is known to exist in the Copper River area, differences in the precise nature of the rocks are thought to make the Copper River basin more prospective for natural gas than for oil.
