Studies in Alaska North Slope

Analyses of a horizontal well drilled in the Shublik Formation within the southern part of the Prudhoe Bay field provide the first glimpse of the unit’s potential as an unconventional resource. The 1450 ft (442 m) long lateral well targeted Shublik Zone B, a distinctive interval on gamma ray logs characterized by subzones of high-low-high values. More than 70% of the well path was maintained within the approximately 17 ft (5 m) thick zone, a feat of efficient geosteering a decade prior to the widespread use of horizontal wells in shale oil and gas reservoirs. On the basis of favorable lithology, hydrocarbon shows, and fracture density, the upper and middle subzones of Zone B should be targeted as a potential unconventional accumulation if and when a well is drilled in the pod of active source rock downdip.