Petrography of Neocomian Sandstones in Western Brooks Range, and Tunalik, Klondike and Burger Wells, Northwestern Arctic Slope-Chukchi Sea: ABSTRACT

Abstract

Petrographic examinations were performed on Neocomian sandstones of the Ellesmerian sequence in outcrop in the western Brooks Range and from cuttings and cores from wells in the northwestern part of the National Petroleum Reserve in Alaska (NPRA) and adjacent Chukchi Sea that are probably coeval with the Kuparuk River Formation in the Prudhoe Bay area. Close similarities are recognized among samples from the 300 foot thick Tingmerkpuk Sandstone, which crops out in the western DeLong Mountains, and samples of apparently coeval intervals in the Tunalik, Burger, and Klondike wells. All are quartzose sublitharenities-quartzarenities that are dominantly fine to very-fine grained, with a few medium-to-coarse-grained sands. Grains are generally well-to very well-sorted, with minor detrital clays. Other framework grains include minor to trace amounts of cherts, argillaceous rocks, carbonate glauconite are commonly present, as rounded peloids, sometimes deformed between more rigid grains. Cements are principally quartz and/or carbonates, with diagenetic clays in a few samples. Notable porosity occurs in some core from the Tunalik well, but is not obvious in these cuttings or outcrop samples (other data indicate porosity in both other wells). Although petrographic characteristics alone do not establish a correlation among these widely spaced control points, the similarities supportmore » a common tectonic/stratigraphic framework for the Neocomian in all the areas. Regional stratigraphic studies of these sandstones suggest potential for significant reservoir quality associated with possible stratigraphic traps in the subsurface.« less