ABSTRACT

The paper addresses gas hydrate as a future energy resource from the perspective of economic geology. The northwestern continental slope of the Gulf of Mexico and the Blake Ridge area in the western Atlantic Ocean each hold approximately similar volumes of hydrate-bound hydrocarbon gas (10 - 14 and 30 trillion cubic meters at standard temperature and pressure, respectively). In the Gulf of Mexico, major gas hydrate accumulations are thought to be thick, structurally localized deposits with high gas hydrate concentration in sediments that are stable because of migration of C₁-C₅ 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 supplied slowly from depth below or generated in situ. Gas hydrate resources in both provinces are characterized by an average degree of geologic assurance. However, geological, technological, economic and safety issues that affect economic feasibility of gas hydrate recovery differ between the areas. Favorable factors such as high resource density and recovery factor, and low development and production costs are characteristic of the structurally-focused 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. The geologic and economic factors listed are 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 seabed instability during future gas hydrate recovery. This study further suggests that the economically extractable global gas hydrate reserve represents only a small portion of the global gas hydrate resource.