AN INTEGRATED APPROACH TO BELUGA AND TYONEK RESERVOIR EVALUATION IN COOK INLET

Reservoir evaluation of the Miocene-aged non-marine reservoirs within the Cook Inlet forearc basin has challenged almost every geoscientist who ever worked the basin. The major challenges are faced in log analysis, stratigraphic interpretation of seismic data and in amplitude versus offset (AVO) analysis. The Beluga Formation is a siltstone-rich unit with locally abundant, thin muddy-sandstones, and abundant thin coals. The Tyonek Formation is comprised of more massively-bedded sandstones with siltstones and abundant, thicker coal beds. Whilst gas detection within the thicker and cleaner Tyonek sands is generally easier because of neutron-density crossover and higher resistivities, evaluation of the Beluga sands, which commonly have 15-20% clay content, is more problematical. Aurora Gas uses a suite of logging, borehole imaging and log evaluation techniques, coupled with extensive sidewall coring to better understand the Beluga and Tyonek reservoirs and their depositional setting. Integration of logs and petrophysics into the seismic domain has also assisted Aurora in maximizing the benefits of recent 3D and 2D data, especially as it relates to gas detection and in-field development.

1Aurora Gas, LLC, 10333 Richmond Avenue, Suite 710, Houston, Texas 77042. Telephone: 713-977-5799, Fax: 713-977-1347, E-mail: acclifford@aurorapower.com.

Submitted for “North to Alaska: Geoscience, Technology & Natural Resources” Joint Technical Conference, Anchorage, May 2006 for AAPG Pacific Section entitled “Reservoir Characterization: Recent Advances in Appraisal and Development”.