MILKOV, ALEXEI V., Texas A&M University, GERG and Dept. of Geology and Geophysics, College Station, TX

ABSTRACT: Gas Hydrate Stability in the Gulf of Mexico: Significance to Resource Estimation, Geohazards, and Global Change

Models of gas hydrate stability for the northern Gulf of Mexico continental slope address basic problems of gas hydrate geology. Resource estimation is based on assessment of the volume of the gas hydrate stability zone and concentration in sediments. Total volume of gas trapped in gas hydrate in the Gulf is estimated to be 100 times less previously predicted. However, structurally-control led accumulations of gas hydrate on the rims of salt withdrawal basins could be economic in the future. Bacterial gas hydrates in salt withdrawal basins are unlikely to represent a significant energy resource because they are disseminated.

Bottom water temperature variations from seasonal changes and warm Loop Current eddies could affect sea-floor gas hydrate stability in the upper 12 m of sediments. A thin but extensive hydrate geohazard zone is hypothesized on the upper Gulf slope in 440-720 m water depth. Petroleum exploitation may be impacted in this zone by sediment deformation from repetitive cycles of gas hydrate formation and dissociation.

It has been suggested that release of methane from sudden decomposition of gas hydrates could cause geologically rapid global change. The potential effect of a 100 meter sea level drop on gas hydrate stability across the slope is not significant. However, large volumes of methane and other greenhouse gases could be released in response to an increase in seafloor water temperature of ~ degrees C.

AAPG Search and Discovery Article #90909©2000 AAPG Foundation Grants-in-Aid