Examination of core samples from the Mount Elbert Gas Hydrate Stratigraphic Test Well, Alaska North Slope : effects of retrieval and preservation
Kneafsey, Timothy J.
Winters, William J.
Boswell, Ray M.
Collett, Timothy S.
MetadataShow full item record
Collecting and preserving undamaged core samples containing gas hydrates from depth is difficult because of the pressure and temperature changes encountered upon retrieval. Hydrate-bearing core samples were collected at the BPXA-DOE-USGS Mount Elbert Gas Hydrate Stratigraphic Test Well in February 2007. Coring was performed while using a custom oil-based drilling mud, and the cores were retrieved by a wireline. The samples were characterized and subsampled at the surface under ambient winter arctic conditions. Samples thought to be hydrate bearing were preserved either by immersion in liquid nitrogen (LN), or by storage under methane pressure at ambient arctic conditions, and later depressurized and immersed in LN. Eleven core samples from hydrate-bearing zones were scanned using x-ray computed tomography to examine core structure and homogeneity. Features observed include radial fractures, spalling-type fractures, and reduced density near the periphery. These features were induced during sample collection, handling, and preservation. Isotopic analysis of the methane from hydrate in an initially LN-preserved core and a pressure-preserved core indicate that secondary hydrate formation occurred throughout the pressurized core, whereas none occurred in the LN-preserved core, however no hydrate was found near the periphery of the LN-preserved core. To replicate some aspects of the preservation methods, natural and laboratory-made saturated porous media samples were frozen in a variety of ways, with radial fractures observed in some LN-frozen sands, and needle-like ice crystals forming in slowly frozen clay-rich sediments. Suggestions for hydrate-bearing core preservation are presented.
Author Posting. © The Author(s), 2009. This is the author's version of the work. It is posted here by permission of Elsevier B.V. for personal use, not for redistribution. The definitive version was published in Marine and Petroleum Geology 28 (2011): 381-393, doi:10.1016/j.marpetgeo.2009.10.009.
Suggested CitationPreprint: Kneafsey, Timothy J., Lu, Hailong, Winters, William J., Boswell, Ray M., Hunter, Robert, Collett, Timothy S., "Examination of core samples from the Mount Elbert Gas Hydrate Stratigraphic Test Well, Alaska North Slope : effects of retrieval and preservation", 2009-10, https://doi.org/10.1016/j.marpetgeo.2009.10.009, https://hdl.handle.net/1912/3125
Showing items related by title, author, creator and subject.
Knapp, Alan K.; Smith, Melinda D.; Hobbie, Sarah E.; Collins, Scott L.; Fahey, Timothy J.; Hansen, Gretchen J. A.; Landis, Douglas A.; La Pierre, Kimberly J.; Melillo, Jerry M.; Seastedt, Timothy R.; Shaver, Gaius R.; Webster, Jackson R. (American Institute of Biological Sciences, 2012-04)The US National Science Foundation—funded Long Term Ecological Research (LTER) Network supports a large (around 240) and diverse portfolio of long-term ecological experiments. Collectively, these long-term experiments have ...
Ponton, Camilo; Giosan, Liviu; Eglinton, Timothy I.; Fuller, Dorian Q.; Johnson, Joel E.; Kumar, Pushpendra; Collett, Timothy S. (American Geophysical Union, 2012-02-14)Spanning a latitudinal range typical for deserts, the Indian peninsula is fertile instead and sustains over a billion people through monsoonal rains. Despite the strong link between climate and society, our knowledge of ...
Duda, Timothy F. (Woods Hole Oceanographic Institution, 2006-12)A three-dimensional (3D) parabolic equation acoustical propagation code has been developed and run successfully. The code is written in the MATLAB language and runs in the MATLAB environment. The code has been implemented ...