FROZEN HEAT | Volume 2

The Gulf of Mexico hydrocarbon generation The Gulf of Mexico hydrocarbon generation

100 Kilometres Scientific drilling expeditions 2005 2009 Scientific drilling expeditions 2005 2009 “BSR” 500 m water depth “BSR” 500 m water depth

GC955

AC21

GC955

AC21

WR313

0

WR313

Source: adapted from U.S. Bureau of Ocean Energy Management

0

100 Kilometres

Source: adapted from U.S. Bureau of Ocean Energy Management Figure 2.8: The Gulf of Mexico is a region of prolific hydrocarbon generation and flux through the shallow sediments. Areas of seafloor amplitude anomalies are shown in black, while areas with geophysical indications of gas hydrate, “BSRs” are shown in orange (see Shedd et al. 2012). Through integration of such geological and geophysical data, the expected distribution of 190 Tcm of methane held in gas hydrate in reservoir quality sands has been interpreted (image courtesy U.S. Bureau of Ocean Energy Management).

trillion cubic metres gas-in-place (mean statistical estimate) in gas hydrates in the northern Gulf of Mexico, 190 trillion cubic metres were likely to occur in sand reservoirs. An initial search for specific gas-hydrate-bearing sands in the deep-water Gulf of Mexico resulted in the first pre-drill estimates of gas hydrate saturation at specific targets (She- lander et al. 2010). Of seven wells drilled, six discovered gas hydrates in sand reservoirs in close agreement with the pre- drill predictions. While these first discoveries are relatively small in size, they are a sampling from a large number of

areas in which geophysical data indicate potential gas hy- drate accumulations (Shedd et al. 2012). The reservoirs are as much as 800 metres below the sea floor, providing the benefits of both warmer and more competent reservoirs, in addition to more effective overlying seals with stronger me- chanical properties. Confirmation of the presence of these deeply buried and well-defined reservoirs from such limited drilling is a promising indicator for basin-wide resource po- tential, and the high success rate of the drilling program fur- ther supports the validity of the integrated geologic systems approach to exploration.

A GLOBAL OUTLOOK ON METHANE GAS HYDRATES 45