OS2C-5:2013 MULTICOMPONENT AND HIGH-RESOLUTION 2D SEISMIC ACQUISITION AT CONFIRMED GAS HYDRATE ACCUMULATIONS IN THE GULF OF MEXICO

Seth HAINES 1，Patrick HART 2, William SHEDD 3，Matthew FRYE 4
1. Central Energy Resources Science Center, U.S. Geological Survey, MS 939, Denver Federal Center, USA,; 2. Pacific Coastal and Marine Science Center, U.S. Geological Survey; 3. U.S. Bureau of Ocean Energy Management, USA; 4. Bureau of Ocean Energy Management, USA

The U.S. Geological Survey led a seismic acquisition cruise at Green Canyon 955 (GC955) and Walker Ridge 313 (WR313) in the Gulf of Mexico in April and May 2013, acquiring multicomponent and high-resolution 2D seismic data.  This field campaign is a major step in the on-going international research program targeting the reservoir-grade gas hydrate accumulations at these sites.

    GC955 and WR313 are established, world-class study sites where high gas hydrate saturations exist within reservoir sands in this long-established petroleum province.  Logging-while-drilling (LWD) data acquired in 2009 by the Gulf of Mexico Gas Hydrates Joint Industry Project provide detailed characterization at the borehole locations, and industry seismic data provide regional- and local-scale structural and stratigraphic characterization.  Significant remaining questions regarding lithology and hydrate saturation between and away from the boreholes spurred new geophysical data acquisition at these sites.  The goals of our 2013 surveys were to (1) achieve improved imaging and characterization at these sites and (2) refine geophysical methods for gas hydrate characterization in other locations.

In the area of GC955 we deployed 21 ocean-bottom seismometers (OBS) and acquired approximately 400 km of high-resolution 2D streamer seismic data in a grid with line spacing as small as 50 m and along radial lines that provide source offsets up to 10 km and diverse azimuths for the OBS.  In the area of WR313 we deployed 25 OBS and acquired approximately 450 km of streamer seismic data in a grid pattern with line spacing as small as 250 m and along radial lines that provide source offsets up to 10 km for the OBS.  These new data afford at least five times better resolution of the structural and stratigraphic features of interest at the sites and enable considerably improved characterization of lithology and the gas and gas hydrate systems.

Our recent survey represents a unique application of dedicated geophysical data to the characterization of confirmed reservoir-grade gas hydrate accumulations.  These new data and interpretations are important progress toward tapping into the vast global reserves of gas hydrate.