Indicators
The occurrence of hydrates can be estimated in well logs, in particular electrical resistivity and sonic logs.
Gas hydrate bearing sediments show anomalously high electrical resistivity and high acoustic velocities. At the base of the gas-hydrate stability zone, which marks the contact between gas-hydrate and free-gas-bearing sediments, a distinct drop in acoustic velocity often characterizes the acoustic log.
Currently, the principal indicator of marine methane hydrates is the detection of bottom-simulating reflectors (BSR's) on seismic data. Unfortunately, in older data these may have been processed away as they were not recognised for what they are. Reprocessing existing data, concentrating on the shallow section and the BSR, should improve estimates of the extent of this resource.