Mercury injection capillary pressure (MICP) results from outcrop samples in the Tyonek, Beluga, and West Foreland Formations, Tyonek and Talkeetna quadrangles, Alaska

The State of Alaska Division of Geological & Geophysical Surveys (DGGS) is currently engaged in a multi-year study of the hydrocarbon potential of the Tertiary and Mesozoic strata in Cook Inlet basin. This report summarizes mercury injection capillary pressure (MICP) data for 38 outcrop samples collected from the Tyonek, Beluga, and West Foreland Formations in the Tyonek and Talkeetna quadrangles. All samples were collected from measured stratigraphic sections. The Tyonek Formation samples have unimodal pore systems and the majority have well defined to sharp intrusion profiles. The Beluga Formation samples are characterized by unimodal pore systems and relatively broad intrusion profiles. The West Foreland Formation samples have much more heterogeneous pore structures and a majority of the samples display some level of bimodality. Six samples from within the various formations have entry pressures above 500 psia and these were evaluated for potential seal capacity. Three of the samples are Type C seals, under the Sneider Classification, and have an average potential seal capacity for oil of 565 feet, and 417 feet for gas (assuming 7.5% hydrocarbon saturation in the seal). One sample from the Beluga Formation is a Type B seal capable of trapping 2,670 feet and 1,971 feet of oil and gas, respectively. The best seals (Type A and A) are from the West Foreland Formation, upper member, and have much higher potential seal capacities, up to 7,132 feet of oil and 5,265 feet of gas for the Type A seal.