The Alaska North Slope is a world-class petroleum province, with nearly 50 years of production from conventionally trapped accumulations. Despite this success, however, the Alaska North Slope remains virtually untapped as an unconventional shale-oil province. Declining volumes in the Trans Alaska Pipeline demand a new look at the presence and effectiveness of potential unconventional plays in this region. A few wells have been drilled in recent years with the purpose of opening up unconventional production in Alaska: Alcor-1 and Merak-1 by Great Bear Petroleum in 2012 and Icewine-1 by 88 Energy in 2015. These wells are located down-dip from producing fields in ideal thermal maturity windows for the Shublik Formation (targeted by Alcor-1 and Merak-1) and the Hue-HRZ (targeted by Icewine-1). Together, these two organic-rich units have generated the bulk of the oil found in existing fields on the North Slope.
In this research, we combine data from the two Great Bear wells with other publicly available data to define the parameters that make the Shublik Formation, in particular, an attractive unconventional shale-oil play south of the existing fields. The formation is regionally extensive, ranges in thickness from about 80 to 300 feet, and has original carbon and hydrogen content of 2 to 4 weight % and 300 to 800 mg HC/g TOC. Moreover, the thermal maturity of the Shublik Formation ranges between 0.9 and 1.5% Ro in the central North Slope, a range that implies a relatively light product capable of flowing easily into the wellbore. The ability to produce that light product by artificial stimulation is likely enhanced by pervasive fracturing in the carbonate-rich Shublik; fractures are observed from the hand sample to seismic scale. This fracturing arose from regional tectonics and uplift of many thousands of feet. This uplift likely preserved overpressure, keeping gas in solution and providing reservoir drive. With directional drilling and hydraulic fracturing, the Shublik Formation can be considered as a commercially sensible resource play in Alaska.
