Gas hydrate saturation estimation from acoustic log data in the 2018 Alaska North Slope Hydrate-01 stratigraphic test well

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Abstract

Completed in December 2018, the Alaska North Slope Hydrate 01 stratigraphic test well provides a wealth of logging-while-drilling (LWD) data for strata to below the base of gas hydrate stability (BGHS). This well is intended to be the first of three wells drilled for a long-term gas hydrate production test to be conducted by the U.S. Department of Energy National Energy Technology Laboratory, the Japan Oil, Gas and Metals National Corporation, and the U.S. Geological Survey (USGS). The Hydrate 01 stratigraphic test well confirmed the presence of gas hydrate in two sand reservoirs within the hydrate stability zone, indicating the suitability of this location for a long-term gas hydrate production test. The USGS, using an effective-medium-theory rock-physics approach, has estimated gas hydrate saturations from compressional (P) and shear (S) wave log data acquired in the Hydrate 01 well. We assume that gas hydrate occurs as pore-filling load-bearing material (i.e., part of the grain matrix). For Unit D, approximately 500 feet above the BGHS, both P-wave and S-wave acoustic logs indicate high gas hydrate saturations with S-wave results slightly lower than those for P-waves. For Unit B, located just above the BGHS, we obtain high gas hydrate saturation estimates from both sonic logs. Our P-wave saturation estimates agree well with results from electrical-resistivity-based estimates, whereas estimates from nuclear magnetic resonance LWD data generally suggest 5 to 10 percent higher saturations; our S-wave results suggest lower saturations. These differences likely indicate complexities in the form of gas hydrate occurrence within the sediment pore space, potentially including differences between hydrate occurrence in Units B and D.

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Publication type Conference Paper
Publication Subtype Conference Paper
Title Gas hydrate saturation estimation from acoustic log data in the 2018 Alaska North Slope Hydrate-01 stratigraphic test well
Year Published 2020
Language English
Publisher US Department of Energy – NETL Program
Contributing office(s) Central Energy Resources Science Center
Description 5 p.
Larger Work Type Book
Larger Work Subtype Conference publication
Larger Work Title Proceedings of the 10th International Conference on Gas Hydrates (ICGH10
Conference Title 10th International Conference on Gas Hydrates (ICGH10)
Conference Location Singapore
Conference Date June 21-26, 2020
Country United States
State Alaska
Other Geospatial North Slope
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