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A GLOBAL OUTLOOK ON METHANE GAS HYDRATES
45
0
100 Kilometres
“BSR”
500 m water depth
AC21
WR313
GC955
The Gulf of Mexico hydrocarbon generation
Source: adapted from U.S. Bureau of Ocean Energy Management
Scientific drilling expeditions
2005
2009
0
100 Kilometres
“BSR”
500 m water depth
AC21
WR313
GC955
The Gulf of Mexico hydrocarbon generation
Source: adapted from U.S. Bureau of Ocean Energy Management
Scientific drilling expeditions
2005
2009
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.
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).