Economic Geology of the Gulf of Mexico and the Blake Ridge Gas Hydrate Provinces

A. V. Milkov and R. Sassen
Geochemical and Environmental Research Group, Texas A&M Univ., College Station, TX

Both the Gulf of Mexico and the Blake Ridge gas hydrate provinces hold approximately similar volume of hydrate-bound hydrocarbon gas (10-13.7 and 30 trillion cubic meters at standard temperature and pressure respectively). The origin of gas hydrate accumulations is different. In the Gulf of Mexico, major gas hydrate accumulations are thought to be thick, structurally localized deposits that are stable because of migration of multiple hydrocarbon gases from the deep subsurface petroleum system into the gas hydrate stability zone. In the Blake Ridge, gas hydrate is disseminated and crystallizes from bacterial methane generated in situ, with lesser methane flux from depth below. Geological, technological, economic and safety issues differ between the areas. Favorable geological factors such as shallow subbottom depth of gas hydrate occurrence and high concentration of gas hydrate in fracture porosity are characteristic of structurallyfocused gas hydrate in the Gulf of Mexico. Well-developed petroleum infrastructure (pipelines etc.) in the Gulf of Mexico may also contribute to eventual cost-effective exploitation of gas hydrate in the future. All these geologic and economic factors listed above are absent or less favorable in the Blake Ridge. Safety considerations are pivotal in the Gulf of Mexico because the common occurrence of gas hydrate in deformed sediments may lead to significant seabed instability during future economic recovery of gas hydrate.

AAPG Search and Discovery Article #90901©2001 GCAGS, Annual Meeting, Shreveport, Louisiana