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Deep Output Overtakes Shallow

Data courtesy of Steve Coseey and Minerals Management Service

FIGURE 1: Number of Operators, Reserves of Fields Discovered

FIGURE 2: Reserves Discovered

TABLE: Gulf of Mexico discoveries

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