A combination of factors including the DWRRA, several key deepwater discoveries, the recognition of
high deepwater production rates, and the evolution of deepwater development technologies, spurred a
variety of deepwater activities. One of the first impacts was a dramatic increase in the acquisition of 3-D
seismic data (figure 2). (Note that figures 2 and 3 illustrate areas permitted for seismic acquisition. The
actual coverage available may be slightly different than that permitted.) Three-dimensional seismic data
are huge volumes of digital energy recordings resulting from the transmission and reflection of sound
waves through the earth.
Figure 2. Progressive deepwater 3-D seismic permit coverage.
These large �data cubes� can be interpreted to reveal likely oil and gas
The dense volume of recent, high-quality data may reduce the inherent risks of traditional
hydrocarbon exploration and allow imaging of previously hidden prospects. Figure 2 illustrates the surge
of seismic activity in the deepwater GOM during the last 12 years. Seismic acquisition has stepped into
progressively deeper waters since 1992. Figure 3 shows the abundance of 3-D data now available. These
data blanket most of the deepwater GOM, even beyond the Sigsbee Escarpment (a geologic and
bathymetric feature in ultra-deep water). Note that many active deepwater leases were purchased before
these 3-D surveys were completed (only the more sparsely populated 2-D datasets were available).
Figure 3. Deepwater Gulf of Mexico 3-D seismic permit coverage from 1992 to 2003..
The seismic permitting coverage shown in figure 3 does not tell the whole story of geophysical activity in
the deepwater GOM. Pre-stack depth migration (PrSDM) of seismic data has greatly enhanced the
interpretation capabilities in the deepwater GOM, particularly for areas hidden below salt canopies.
While PrSDM was once used sparingly, the availability of large speculative PrSDM surveys allows the
widespread use of this technology in the early phases of exploration. Subsalt discoveries like Mad Dog,
Thunder Horse, North Thunder Horse, Atlantis, and Tahiti demonstrate the importance of subsalt
Figure 4 provides a partial inventory of speculative PrSDM coverage.
Figure 4. Pre-stack depth migration coverage from various industry sources.
This figure was assembled from publicly available sources and provides a good indication of the current widespread
coverage of PrSDM processing.
Time-lapse seismic surveys (also known as 4-D) will likely be the next significant seismic technology to
be applied routinely in the deepwater GOM. The technique can be applied to characterize reservoir
properties, monitor production efficiency, and estimate volumetrics from inception through the life of the
field (Shirley, 2001). The high cost of drilling deepwater wells and challenges associated with reentry of
deepwater wells may promote the use of 4-D technology in the deepwater GOM.
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Cover and Title Page
DRILLING AND DEVELOPMENT
RESERVES AND PRODUCTION
SUMMARY AND CONCLUSIONS
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