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Reflection Seismology Program

Gas Hydrates



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Methane-Hydrate Resource Characterization Research

    Methane/gas hydrates, a frozen framework of methane (or other light hydrocarbons) and water, occur beneath thick permafrost in Alaska and other arctic regions, and are seen as BSRs or "bottom - simulating reflections" in seismic reflection data from many offshore areas around the world.  Gas hydrates may eventually be an important energy resource because of their widespread distribution and because they may provide a fuel that is cleaner burning than ordinary natural gas. Gas hydrates also may play an important role in Earth's climatic variations.

    The University of Arizona is working with the University of AlaskaGH-Index_map.gif (238454 bytes) (Fairbanks) in a Department of Energy-funded research collaboration with BP Alaska.  BP produces petroleum from deep reservoirs in such areas as the Prudhoe Bay field, but very little is known about gas-hydrate resources that lie at shallow levels in these fields, well above the depths at which oil and gas are presently produced.  Gas hydrates are considered to be an experimental resource, and the Department of Energy is actively interested in learning more about such resources in arctic regions as well as in other areas such as the Gulf of Mexico.

   At the University of Arizona, researchers from the Departments of Geosciences (Dr. Roy A. Johnson and his students) and Mining and Geological Engineering (Dr. Mary Poulton, Dr. Robert Casavant and Dr. Charles Glass and their students) are combining their efforts to study this unusual potential resource. Our initial research goal is to delineate the extent of in-situ gas-hydrates and associated free gas beneath Alaska's North Slope* based on seismic character and seismic attributes from large 3-D seismic reflection data sets.  This effort involves calibration of gas-hydrate occurrences known from borehole data with seismic properties in the 3-D seismic reflection data and, in the longer term, will begin to focus on the development of effective techniques to facilitate automatic detection and characterization of potential areas of gas-hydrate concentrations.

ANS Gas Hydrates-X-section-2.gif (58411 bytes)    Free gas dramatically changes the acoustic impedance within reservoir rocks and often results in very strong seismic reflectivity from gas-saturated zones.  Evidence suggests that BSRs associated with gas-hydrate occurrences most likely are imaged as strong reflections because of the presence of free gas above or below the frozen gas hydrates.  The complex association of gas hydrates, free gas and permafrost make identification and quantification of diagnostic attributes an important goal in the ultimate development of effective exploration techniques and delineation of development targets.

    This project was the focus of newspaper articles in both the Tucson Citizen ("Searching for New Sources of Energy: Trapped to Tapped," by Mari N. Jensen, 12/11/01) and Arizona Daily Star ("UA to Study Viability of New Natural Gas Source," by Eric Swedlund, 12/11/01) (and even warranted notice as the Arizona State news in USA Today's state-by-state news snippets!).

*Note that this research project does not include the Arctic National Wildlife Refuge.