Seismic stratigraphy near the Tunalik well, North Slope, Alaska
- Geological Survey, Denver, CO (United States)
- Alaska Division of Geological and Geophysical Surveys, Fairbanks, AK (United States)
- Geological Survey, Menlo Park, CA (United States)
The Tunalik No. 1 well was drilled to 20,335 feet in 1978 on the North Slope of Alaska (northwest corner of the National Petroleum Reserve), terminating in Pennsylvanian limestones. A strong gas kick occurred at 12,500 feet in the Jurassic-Early Cretaceous Kingak Shale unit (11,400-14,400 feet), and drilling was shut down for a month before control was regained.Seismic profiles in the vicinity of Tunalik indicate that the gas kick occurred in the forest beds of a 1500-feet-thick deltaic system that was prograding to the south and west during deposition. The uppermost (topset) part of the deltaic system consists of an upward-coarsening 300-feet sandstone interval - an apparent equivalent of sandstones of the Kuparuk Formation. The gas kick occurred within a lower 100-feet-thick sandy unit, which has velocities (12,000 feet/second), high densities (2.6-3.0 g/cc), and high resistivities that decrease upward, indicating an overall fining-upward sequence. The densities in the lower part of the sandy unit are 2.8-3.0 g/cc and appear to reflect some combination of naturally occurring pyrite in the sediments and barite that was injected while regaining control of the well. Vitrinite reflectance values (Ro) within the Kingak in the Tunalik well are 2.0-3.5, compatible with the occurrence of gas. The total organic carbon measurements average below 1% with only a few samples in the 1.2% range. The Alaskan Division of Geological and Geophysical Surveys and the U.S Geological Survey are initiating (1) a seismic stratigraphic study in an attempt to identify sequences in the northwestern part of the National Petroleum Reserve which might have more favorable hydrocarbon potential and (2) a study of the relationship of the turbiditic sandstones of the Kingak to the quartzose Tingmerkpuk sandstone that crops out in the western Brooks Range.
- OSTI ID:
- 75410
- Report Number(s):
- CONF-9505199-; ISSN 0149-1423; TRN: 95:003618-0014
- Journal Information:
- AAPG Bulletin, Vol. 79, Issue 4; Conference: American Association of Petroleum Geologists (AAPG) Pacific Section meeting, San Francisco, CA (United States), 3-5 May 1995; Other Information: PBD: Apr 1995
- Country of Publication:
- United States
- Language:
- English
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