Methane Hydrate Resource Assessment of the Outer Continental Shelf: In-Place Gulf of Mexico Results

Matthew Frye¹, John Grace³, Jesse Hunt², Gordon Kaufman⁵, John Schuenemeyer⁴, and Bill Shedd^2
1Resource Evaluation Division, Minerals Management Service, Herndon, VA
²Minerals Management Service, New Orleans, LA
³Earth Science Associates, Long Beach, CA
⁴Southwest Statistical Consulting, Cortez, CO
⁵Massachusetts Institute of Technology, Cambridge, MA

The Minerals Management Service (MMS) is a U.S. Department of the Interior agency responsible for managing the mineral resources of the U.S. Outer Continental Shelf (OCS). The MMS is finalizing the first comprehensive assessment of potential gas hydrate resources on the OCS since a USGS-led 1995 effort. The first release is expected at the end of 2007 and will include a preliminary distribution of in-place resources for the Gulf of Mexico (GOM).

Regional MMS personnel assessed approximately 425,000 km² in the GOM where pressure and temperature conditions provide a stable physical environment for the formation of hydrate, and where seismic data are available for subsurface interpretation. GOM-wide interpretations of shallow sand distribution, seafloor amplitude anomalies, bathymetry, and depth to salt were generated using the MMS proprietary seismic database. Supporting subsurface data (wellbore, geological, etc.) were integrated with the geophysical data.

The GOM assessment model structure consists of nearly 200,000 cells that measure 2.32 km² each. The stochastic FORTRAN-based model incorporates the uncertainty of many input variables through multiple trial runs, producing a distribution of results where the mean is the expected value. The model methodology is based on mass balance, where inputs include an initial endowment of TOC, a volume of candidate reservoir rock, and a fraction of the rock volume that allows for hydrate concentration.

Input and output data for the GOM are spatially referenced and allow for hydrate resources to be distributed with reference to underlying geologic features. Relatively large volumes of these resources are estimated to accumulate near the margins of intra-slope minibasins and near the front of the Sigsbee Escarpment.

AAPG Search and Discover Article #90078©2008 AAPG Annual Convention, San Antonio, Texas