Petrologic-petrophysical relationships, West Sak and Ugnu (Brookian), northern Alaska
- U.S. Bureau of Land Management, Anchorage, AK (United States)
- Univ. of Alaska, Fairbanks (United States)
Petrographic-mineralogic analyses have been combined with petrophysical information derived from wireline logs, as part of an investigation of geological and engineering characteristics of the West Sak and Ugnu (Brookian) stratigraphic intervals in several wells in the central portion of the Alaskan Northslope. The strata are semi- to unconsolidated clastics - sand, silt, clay in size - 'cemented' by viscous (API gravity 8{degree} to 22{degree}) hydrocarbon material. This presents serious problems in terms of sample integrity during borehole recovery and subsequent storage, transportation, and sample preparation. Textural relationships in thin section are often problematic with respect to original relationships in the undisturbed subsurface. In-situ analyses - e.g., wireline logs -represent the potentially most useful means of elucidating petrophysical-engineering properties of concern to drilling, completion, and production. Petrographic-mineralogic analysis of sample materials, as feasible, is essential for rigorous application of such in-situ techniques. The present work confirms the heterogeneous nature of the West Sak and Ugnu intervals, with frequent, often substantial proportions of silt-clay size materials associated intimately within, and/or interbedded with, coarser grained reservoir intervals. Major intervals with moderate-good reservoir properties are recognized, as well as significant intervals ranging from relatively poor reservoir quality to good seal quality materials. Hydrocarbon production will undoubtedly require enhanced recovery techniques, hence thorough, detailed reservoir/nonreservoir characterization will be imperative to achieve viable efficiency.
- OSTI ID:
- 7024894
- Report Number(s):
- CONF-910403--
- Journal Information:
- AAPG Bulletin (American Association of Petroleum Geologists); (United States), Journal Name: AAPG Bulletin (American Association of Petroleum Geologists); (United States) Vol. 75:3; ISSN AABUD; ISSN 0149-1423
- Country of Publication:
- United States
- Language:
- English
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