Bottom‐simulating reflectors (BSRs) on marine seismic data are commonly used to identify the presence of natural gas hydrate in marine sediments, although the exact relationship between gas hydrate and BSRs is undefined. To clarify this relationship we compile a data set of probable gas hydrate occurrence as appraised from well logs of 788 industry wells in the northern Gulf of Mexico. We combine the well log data set with a data set of BSR distribution in the same area identified from 3‐D seismic data. We find that a BSR increases the chances of finding gas hydrate by 2.6 times as opposed to drilling outside a BSR and that the wells within a BSR also contain thicker and higher resistivity hydrate accumulations. Even so, over half of the wells drilled through BSRs have no detectable gas hydrate accumulations and gas hydrate occurrences and BSRs do not coincide in most cases.

No abstract

The northern Gulf of Mexico is known to host gas hydrate in submarine sediments. Estimating the amount of gas hydrate for both carbon cycle and resource interest has been ongoing for more than three decades. A large range of estimates (from 0.2 to 680 trillion cubic meters (TCM)) for hydrate‐bound natural gas at standard temperature and pressure exists. We bring a new perspective to resource estimates by using ~800 publicly available petroleum industry well logs assessed for natural gas hydrate. Our resulting probabilistic range of the gas hydrate‐bound natural gas in the northern Gulf of Mexico ranges from 37 TCM (10th percentile estimate) to 78 TCM (90th percentile estimate) of gas hydrate‐bound natural gas, with a mean estimate of 56 TCM. This suggests that the gas hydrate resource density of the northern Gulf of Mexico is 4 times lower than that previously estimated by the Bureau of Ocean Energy Management. Our results also indicate that over half of the gas hydrate in the area is strategically hosted in sand reservoirs, which is significantly higher than that previously estimated.

Bottom simulating reflections that sometimes mark the base of the gas hydrate stability zone in marine sediments are often identified based on reverse polarity reflections that cut across stratigraphic layering in seismic amplitude data. On the northern U.S. Atlantic margin between Cape Hatteras and Hudson Canyon, legacy seismic data have revealed pronounced bottom simulating reflections south of the deepwater extension of Hudson Canyon but more subtle ones from offshore Delaware south to Cape Hatteras, where the reflections sometimes follow stratigraphic layering. Using high-resolution seismic data acquired during the 2018 Mid-Atlantic Resource Imaging Experiment and a supervised neural net, we identify seismic features associated with gas hydrates and/or the top of gas between Hudson Canyon and Cape Hatteras. Using seismic attributes sensitive especially to the presence of gas, we train a neural network algorithm on seismic data from an area with strong bottom simulating reflections and then apply the model to the rest of the data set. The results indicate that gas hydrate and/or shallow free gas are far more widespread on the northern part of the U.S. Atlantic margin than previously known. Seismic indicators of gas extend landward from the 2000 m isobath to the upper continental slope in sectors with (offshore Virginia) and, to a lesser extent, without (offshore New Jersey) pervasive upper slope methane seeps. Higher sand content and intermediate sediment thickness, factors related to the container size and gas charge in a petroleum systems framework, are associated with more robust gas indicators.