Hydrate and Free Gas Exploitation Along the Northern Gulf of Mexico Continental Slope

Allen Lowrie¹ and Carol Lutken^2
1 Consultant, Picayune, MS
² Mississippi Mineral Resources Institute, University, MS

Hydrates and free gases within the upper km of unconsolidated sediments along the northern Gulf of Mexico continental slope comprise potentially major petroleum exploration and exploitation targets. Increasing cost of hydrocarbons, improvements in interpretative and modeling techniques and in drilling abilities make these hydrocarbon accumulations increasingly attractive. Hydrates are abundantly described along the seafloor from shelfbreak to upper and middle slope. Geophysical techniques and data from drilling appear adequate to locate and map hydrates and free gases. Understanding of depositional environments, concomitant tectonic development, and hydrogeologic flowage patterns are sophisticated enough that adequate comments may be made regarding the mechanical strength and stability of local and regional continental margin geology as well as trends for hydrocarbon transportation and subsequent enrichment by subsurface flow. Such abilities are required because when exploitation commences, as with hydrocarbon extraction, strength and stability will change. Exploitation of these potential reservoirs requires converting hydrates to free gas or harvesting the gases. The exploration phase includes locating and measuring the exploitable reservoirs. The exploitation phase requires determining safe means of removing gases while maintaining the site's structural integrity. A major structural collapse and resultant release of trapped gases would impact continental margin stability and possibly global climate. Throughout the exploration and exploitation phases, judicious use of vertical and horizontal/inclined drilling is mandatory. The technological key needed to make these suggestions a commercial reality is the ability to drill horizontal and inclined wells greater distances than is possible at present. Using very large drilling equipment, wells may extend out to ~10 km. What modifications are needed to double the drilling radius in unconsolidated sediments?