technology continues to drive offshore activity offshore for the
deep gas play in the Gulf of Mexico.
year the Minerals Management Service increased its estimates for
deep gas in the Gulf of Mexico shelf by 175 percent, to 55 trillion
cubic feet of gas. This change was based on:
from several deep gas fields.
seismic data acquired and processed using the latest technology
to improve imaging at greater depths.
seismic, along with gravity and magnetic data, have resulted in
new conceptual plays that bode well for the deep gas play's future,
according to the MMS.
technological developments have improved imaging at depth, allowing
oil companies to begin probing the potential of deeper targets —
and with the number of deep gas successes on the rise, seismic contractors
are pushing the limits for higher quality imaging of these deeper
not surprising, given the growth in the deep gas play on the shelf,
that a growing list of geophysical contractors are targeting the
play as a part of their business plan.
late last year, TGS-NOPEC completed the acquisition of its newest
long-offset 2-D seismic survey, which spans a large part of the
Gulf of Mexico with more than 28,000 line miles of data acquired
with 8,000-meter offsets and record lengths of up to 13 seconds.
The project was specifically designed to image targets as deep as
to Karen El Tawil, vice president for TGS-NOPEC, the program's two-mile
by two-mile grid is intended to aid companies in identifying the
large deep structures capable of holding large quantities of natural
data is packaged into five stack sections, including four evenly
distributed corridor stacks. The sections enable analyses of amplitude
variations with offset, he said, which is another critical technology
for companies searching for deep structures missed by older 2-D
and 3-D seismic surveys.
with the 2-D regional survey, the company initiated a regional evergreen
interpretation project based on the new data coupled with biostratigraphic
data. "The interpretation will be updated quarterly and is geared
toward aiding explorationists to better understand the deep shelf's
regional geology," said AAPG member, John Adamick, TGS-NOPEC's vice
president of business development.
surfaces include Lower Pliocene, Miocene and upper Oligocene," he
said. "Isochron maps created between horizons will show locations
of depocenters and fairways within stratigraphic intervals."
analog field studies are included in the initial interpretation
project, and more analog studies will be added as well control data
from new fields becomes available. The analogs could provide a valuable
catalog of what deep gas fields look like across the Louisiana shelf.
TGS-NOPEC also began acquisition and processing on a 3-D survey
that integrates multi-pass streamer data with 9,000-meter offsets
and ocean bottom cable seismic with up to 10,000-meter offsets.
Although all offset data will be acquired, those greater than 8,000
meters will not be infilled.
will cover more than 250 blocks in the Ship Shoal Addition and South
Timbalier planning areas.
a seamless, integrated survey, both streamer and OBC receivers have
been used to simultaneously acquire seismic signal data with two
different crews. The survey is using 40-meter cross line spacing
and 20 meter by 25 meter bins.
the 2-D survey that is geared toward identifying prospective subsurface
structures, 3-D long offset seismic data is designed to define drilling
prospects in the deep gas play's sweet spots and it covers many
of the wells that are currently being drilled.
to AVO analysis, seismic contractors point to pre-stack time migration
and pre-stacked depth migration technology as important advancements
for the deep gas play.
offset and record length seismic is a key to unlocking the secrets
of buried reservoirs, there are real hurdles to overcome on the
surface. The shelf's extensive infrastructure makes developing deep
gas targets more economic, but it makes acquiring long offset seismic
TGS-NOPEC resorted to acquiring streamer data for its 3-D long offset
survey in multi-pass mode — recording data in two passes with a
the difficulties of acquisition is the fact that this effort falls
in the middle of a heavily obstructed offshore area. The TGS-NOPEC
vessel carries six streamers side by side that extend over a half-a-mile
wide and each streamer is almost three miles long. In fact the total
area towed is equivalent to 672 football fields.