Exploration and Production Potential of the Point Thomson Area, North Slope Alaska
Kenneth P. Helmold, Steven R. Moothart, Paul L. Decker, Paul C. Anderson, Donovan L. Krouskop, Diane P. Shellenbaum, Julie A. Houle, John D. Hartz, John F. Meyer, and Teri A. Arion
Alaska Division of Oil & Gas, Anchorage, AK
The prolific northern Alaska petroleum province extends nearly 700 miles from the Mackenzie Delta of arctic Canada to the Russian maritime border in the Chukchi Sea. More than 50 oil and gas accumulations have been discovered, most along the regional structural high of the Barrow Arch that developed during Lower Cretaceous rifting. In the eastern portion of the province the Point Thomson area is underlain by oil, natural gas and gas condensate deposits within the Lower Cretaceous (Neocomian) Thomson sand, and by oil in the overlying Paleocene sandstones of the Brookian sequence.
Hydrocarbons in the Point Thomson area were first discovered in 1975 in the Alaska State A-1 well that tested 23° API gravity oil at a rate of over 2,500 BOPD from Paleocene turbidites of the Brookian Canning Formation. In 1977 the Point Thomson No. 1 well tested the Thomson sand at a rate of over 2,200 BOPD (18° API gravity oil) and 13 MMCFGPD. Fifteen wells were subsequently drilled in the Thomson area. The Thomson sand holds undeveloped recoverable reserves of 295 MMBO and 8 TCFG.
The Thomson reservoir comprises non-marine to shallow marine fan-delta deposits containing conglomerate and sandstone shed southward off the emergent Barrow Arch. It contains significant detrital dolomite and quartz derived from a nearby provenance area underlain by northerly-dipping pre-Mississippian metasedimentary terrane. The reservoir interval grades laterally into siltstone deposited in an offshore environment. The overlying Brookian reservoir consists of deep-water turbidites transported northeastward from shelf-slope settings. They contain a higher proportion of argillaceous sedimentary and metasedimentary detritus derived from the Brooks Range. Both horizons have good reservoir quality which is aided by strong overpressure in the Thomson sand and moderate overpressure in the Brookian sands.
AAPG Search and Discover Article #90078©2008 AAPG Annual Convention, San Antonio, Texas