Presented by Bill Shedd - Geophysicist, Minerals Management Service
William (Bill) Shedd is the MMS Contract Inspector and the Geophysicist involved in the site selection process for the May ‘06 Alvin dives and the June '07 Jason cruise. Along with Dr. Harry Roberts of Louisiana State University and Jesse Hunt of the MMS, Bill used 3D seismic bathymetry with amplitude extraction overlay to pick the sites. He has been involved in site selection for the MMS sponsored Johnson Sea-Link dives researching both natural gas hydrate distribution and chemosynthetic communities in the Gulf of Mexico, and is presently involved in the assessment of natural gas hydrates as a potential resource in the Gulf and the Atlantic. After receiving a B.A. in Geology from the University of Rochester and after completing coursework toward a Masters of Geology at Louisiana State University, Bill worked in the oil industry for 22 years before joining the MMS in 1997.
Bill Shedd, Jesse Hunt, and others at the MMS have mapped the seafloor reflector for bathymetry with amplitude extraction over 156,000 square miles of the Gulf of Mexico with industry acquired time migrated 3-D data. The resulting maps have been used for several purposes, but one of the most interesting and significant use of the mapping has been to identify anomalous amplitude responses generated by oil and gas seeps - both high positive amplitudes (indicating hard seafloor and chemosynthetic communities) and low positive to negative amplitudes (indicating very soft, gas saturated seafloor and mud volcanoes). Congress mandated the MMS to protect the chemosynthetic communities that live off the hydrocarbon and associated hydrogen sulfide at these seep sites and the MMS has used the mapping to understand the distribution of these chemosynthetic communities and the subsurface hydrocarbon migration system feeding them. To date, over 4,700 amplitude anomalies have been identified, primarily in the Central Planning Area and the Eastern half of the Western Planning Area of the Gulf of Mexico. Of those sites, only about 60 sites have been groundtruthed by direct observation and sampling from manned submersibles (the “Alvin” and the “Johnson SeaLink”) and ROV’s (the “Jason”), 32 between 2000 and 2007. The video and stills presented today are just a few minutes out of hundreds of hours taken by several cameras documenting the richness in diversity and lushness of the these communities and the interesting geology that support them in 1,500 feet to over 9,000 feet of water.