Geologic controls on gas hydrate occurrence in the Mount Elbert prospect, Alaska North Slope
Boswell, Ray M.
Rose, Kelly K.
Collett, Timothy S.
Lee, Myung W.
Winters, William J.
Lewis, Kristen A.
MetadataShow full item record
Data acquired at the BPXA-DOE-USGS Mount Elbert Gas Hydrate Stratigraphic Test Well, drilled in the Milne Point area of the Alaska North Slope in February, 2007, indicates two zones of high gas hydrate saturation within the Eocene Sagavanirktok Formation. Gas hydrate is observed in two separate sand reservoirs (the D and C units), in the stratigraphically highest portions of those sands, and is not detected in non-sand lithologies. In the younger D unit, gas hydrate appears to fill much of the available reservoir space at the top of the unit. The degree of vertical fill with the D unit is closely related to the unit reservoir quality. A thick, low-permeability clay-dominated unit serves as an upper seal, whereas a subtle transition to more clay-rich, and interbedded sand, silt, and clay units is associated with the base of gas hydrate occurrence. In the underlying C unit, the reservoir is similarly capped by a clay-dominated section, with gas hydrate filling the relatively lower-quality sands at the top of the unit leaving an underlying thick section of high-reservoir quality sands devoid of gas hydrate. Evaluation of well log, core, and seismic data indicate that the gas hydrate occurs within complex combination stratigraphic/structural traps. Structural trapping is provided by a four-way fold closure augmented by a large western bounding fault. Lithologic variation is also a likely strong control on lateral extent of the reservoirs, particularly in the D unit accumulation, where gas hydrate appears to extend beyond the limits of the structural closure. Porous and permeable zones within the C unit sand are only partially charged due most likely to limited structural trapping in the reservoir lithofacies during the period of primary charging. The occurrence of the gas hydrate within the sands in the upper portions of both the C and D units and along the crest of the fold is consistent with an interpretation that these deposits are converted free gas accumulations formed prior to the imposition of gas hydrate stability conditions.
This paper is not subject to U.S. copyright. The definitive version was published in Marine and Petroleum Geology 28 (2011): 589-607, doi:10.1016/j.marpetgeo.2009.12.004.
Suggested CitationMarine and Petroleum Geology 28 (2011): 589-607
Showing items related by title, author, creator and subject.
Physical properties of sediment from the Mount Elbert Gas Hydrate Stratigraphic Test Well, Alaska North Slope Winters, William J.; Walker, Michael; Hunter, Robert; Collett, Timothy S.; Boswell, Ray M.; Rose, Kelly K.; Waite, William F.; Torres, Marta E.; Patil, Shirish; Dandekar, Abhijit (Elsevier B.V., 2010-01-18)This study characterizes cored and logged sedimentary strata from the February 2007 BP Exploration Alaska, Department of Energy, U.S. Geological Survey (BPXA-DOE-USGS) Mount Elbert Gas Hydrate Stratigraphic Test Well on ...
Downhole well log and core montages from the Mount Elbert Gas Hydrate Stratigraphic Test Well, Alaska North Slope Collett, Timothy S.; Lewis, R. E.; Winters, William J.; Lee, Myung W.; Rose, Kelly K.; Boswell, Ray M. (Elsevier B.V., 2010-03-27)The BPXA-DOE-USGS Mount Elbert Gas Hydrate Stratigraphic Test Well was an integral part of an ongoing project to determine the future energy resource potential of gas hydrates on the Alaska North Slope. As part of this ...
Examination of core samples from the Mount Elbert Gas Hydrate Stratigraphic Test Well, Alaska North Slope : effects of retrieval and preservation Kneafsey, Timothy J.; Lu, Hailong; Winters, William J.; Boswell, Ray M.; Hunter, Robert; Collett, Timothy S. (2009-10)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 ...