Data courtesy of Steve Coseey and Minerals Management Service
Wells to Test GOM Hydrates
Gas hydrates are another future resource in the deepwater Gulf
of Mexico; these resources may be 30 to 300 times greater than conventional
oil and gas reserves, the MMS report indicates.
In an effort to learn more about hydrates, the MMS, the Department
of Energy and seven service companies plan to kick off a joint venture
this year. About eight 1,000- to 2,000-foot deep wells will be drilled,
logged and cored through bedded hydrates near seafloor hydrate mounds
in Atwater Valley and Keathley Canyon. The project hopes to calibrate
the geophysical data for characterizing buried gas hydrates.
The MMS is developing a gas hydrates assessment model, and will
complete an initial inventory of recoverable hydrates in 2005.
Gas hydrates in the Gulf occur in water depths greater than 1,450
feet, and each cubic foot of hydrate yields about 160 feet of gas
at standard temperature and pressure.
Piston cores have sampled about 100 sites that contain both thermogenic
and bioorganic gas hydrates:
- Thermogenic gas hydrates, derived from deeply buried, organic-rich
sediments or existing gas reservoirs and containing a mixture
of complex hydrocarbon gases, are known only in the Gulf of Mexico.
- Biogenic gas hydrates, generated at shallow depths by bacterial
decomposition of organic matter and yielding primarily methane
gas, are found in other marine settings around the world.
The MMS report notes there are many unanswered questions about
the distribution, concentration, reservoir properties and stability
of hydrates. Conventional drilling operations do not allow for sampling
of the upper 3,000 feet of sediment where hydrates occur.
Although conventional 3-D seismic are not specifically designed
to detect hydrate deposits, interpretive techniques have been used
to delineate possible hydrates.
-- KATHY SHIRLEY