Establishing an association between BSRs and gas hydrate accumulations in the Northern Gulf of Mexico

Abstract:

In this research, we search for a relationship between bottom simulating reflectors (BSRs) and gas hydrate accumulations identified on petroleum industry well logs in the northern Gulf of Mexico. From our analysis of petroleum industry wells, we have found over 600 wells drilled on the Gulf of Mexico continental slope that penetrate the gas hydrate stability zone and contain well logs useful for appraising gas hydrate accumulations. We identify natural gas hydrate in petroleum industry wells based on an increase in resistivity of at least 0.5 ohm*m from the background resistivity. Using this criterion, we have identified at least 40 wells with gas hydrate occurrence. Some of these new prospects have significant hydrate accumulations. For example, in Alaminos Canyon Block 810 we found a natural gas hydrate accumulation with up to 10 ohm*m resistivity above the background resistivity and over 715 feet of hydrate.

BSRs occur at many gas hydrate sites near the thermodynamic base of the gas hydrate stability zone, but , as many recent drilling expeditions have shown, drilling a BSR is not a guarantee of locating a natural gas hydrate accumulation. We will combine a comprehensive analysis of BSRs on the continental slope with our extensive basin-wide review of gas hydrate accumulations occurring in petroleum industry wells in this area. We will consider both traditional (also called continuous) BSRs, which are uninterrupted seismic events that mimic the seafloor and discontinuous BSRs which are disparate individual seismic events that usually appear along dipping strata. By combining these singular data sets, we will identify a relationship between BSR occurrences and gas hydrate accumulations in the northern Gulf of Mexico.