Exploration for deep-water sandstone reservoirs
beneath allochthonous salt in the Gulf of Mexico represents a major new
frontier play in North America. More than 30 wells thus far have been drilled
with subsalt targets, resulting in 8 discoveries, at least 3 of which are
commercial and 3 that have reserves of 100 million bbl oil equivalent or
more. Reservoirs consist of Miocene-Pleistocene sandstones deposited in
submarine fan channel system environments on the paleoslope, where salt
deformation has a complex late Cenozoic history. Salt sheets exist at various
stratigraphic levels and have overridden sandstone fairways on the present-day
outer continental shelf and upper slope, where water depths are moderate
and where pipeline and other infrastructure facilities already exist. Potential
reserves for the subsalt play have been estimated at 1.2 billion bbl of
oil and 15 Tcf* gas from 25 or more significant fields.
Recent success in the subsalt play has depended
upon (1) advances in 3-D (three-dimensional) seismic acquisition and processing
(in particular, 3-D prestack depth imaging) and (2) improved geologic modeling
of salt deformation and depositional systems. In addition, better understanding
of the drilling
©Copyright
1997. The American Association of Petroleum Geologists. All rights reserved.
1Petroleum
Consultant, 1511 18th Avenue East, Seattle, Washington 98112.
2Anadarko
Petroleum, 17001 Northchase Drive, Houston, Texas 77060.
Grateful
acknowledgment is made to Anadarko Petroleum, Phillips Petroleum, TGS-Calibre
Geophysical Company and Geco-Prakla for permission to use data included
in this report. Appreciation is also extended to Holly Harrison for helpful
comments, to Anadarko Petroleum for preparation of figures, to Floyd Bardsley
for additional artwork, and to Robert O. Brooks, Clint Moore's coauthor.
Send reprint
requests to AAPG Publications Manager, P.O. Box 979, Tulsa, Oklahoma 74101-0979.
*Tcf = trillion
cubic feet; Gcf = billion cubic feet; Mcf = million cubic feet.
