American Oil and Gas Reporter - August 2019 - 66

SpecialReport: Seismic & Geophysics
cause of the congestion, the challenging
part is getting surface permits so that
there are not lots of areas within a survey
layout where data cannot be acquired. It
takes time to get all the permits, but it's
worth it."
He adds that the company uses existing
roadways to layout and deploy equipment
whenever possible. "It can be a little
scattered when we get into towns, but if
you do a good job with the permitting
and can get Vibroseis™ through the area,
data quality can be kept consistent with
minimal skipped areas," McCrossin states,
pointing out that the ARIES system also
enables "live" analysis to ensure quality
control as data collection proceeds.
"You can see the data in real time as it
is being recorded," McCrossin relates.
"If quality starts falling off, we can
increase the source energy or maybe determine that it is too noisy and temporarily
hold up on shooting. There could be an
airplane passing over some loud surface
activity. Real-time QC is the only way to
have this knowledge and accommodate
for issues while recording is active."
When coupled with the GS-32CT closetolerance geophones for more usable data
across the seismic bandwidth, he says
ARIES also gives Precision Geophysical
the flexibility to design richer and higherdensity surveys to meet client needs in
the Marcellus/Utica. "As operators step
out into less proven drilling areas, they
generally run Vibroseis reconnaissance
2-D lines to figure out where to focus follow-up 3-D surveys," he remarks.

Then, the 3-D surveys are laid out on
tight grids with closer line spacing, and
often include larger recording patches to
achieve longer offsets for wider azimuths,
McCrossin explains. "Our projects typically have channel counts of 5,000-10,000,
which enables the richer datasets and
higher resolutions," he concludes.
High-Density Survey
Almost a decade ago, Fairfield Geotechnologies set off to build a large contiguous database in the Delaware Basin.
The DB1 survey conducted at that time
had five times the density of previous surveys, collecting nearly 1.4 million traces
per source square mile, says Joe Dryer,
president of Fairfield Geotechnologies.
Then in 2017, the company's Red
Tank survey to the north increased coverage by 20 percent, with more than 1.6
million traces per source square mile for
the same number of source points. "There
was an immediate impact on image quality," Dryer remarks.
Now Fairfield's latest Permian survey,
which began in early 2019, is 10.5 times
the density effort at Red Tank, he reports.
The C-Ranch project has 16.8 million
traces per source square mile and 1,369
source points. "Trace density is now beyond
what seemed possible only a few years
ago," states Dryer. "We believe the new
parameters will greatly benefit rock properties characterization, improve signal-tonoise ratio, and result in better imaging."
In South-Central Louisiana, Fairfield
is partnered with CGG on a frontier Austin

Fairfield Geotechnologies' C-Ranch high-density survey in the Permian Basin has 16.8
million traces per source square mile and 1,369 source points. In some areas in the Permian, a shallow high-velocity anhydrite zone greatly complicates imaging. New survey
parameters that densely sample the subsurface in offset and azimuth lead to better velocity models that improve imaging.

66 THE AMERICAN OIL & GAS REPORTER

Chalk opportunity. The project is analogous
to Texas in that a significant uplift in
trace density will provide a better understanding of the formation, which has recently regained industry interest, Dryer
notes. The project deliverables include
AVO-compliant and inversion ready data
for fast-track reservoir characterization.
Full-azimuth, long-offset 3-D data
from these surveys offer the potential
for significantly better insights into
rock properties key in field planning,
Dryer explains. "As data quality has
improved, operators have increasingly
looked to seismic data to find sweet
spots," he says. "Additionally, seismic
is playing an increasingly important
role in well spacing, lateral orientation
and enhanced recovery."
Trace density is particularly helpful
in understanding the complex near-surface
geology common in some areas of the
Permian Basin. "Careful processing of
high trace-density data helps see through
seismic signal distortion caused by this
complexity," notes Dryer. "Adding knowledge of the subsurface and geologic constraints to the velocity model results in
greatly improved seismic imaging, ultimately leading to greater exploration success with lower risk."
Similarly, in the marine environment
new "sparse" ocean-bottom nodal geometries are acquiring long-offset, full-azimuth
data required by imaging techniques such
as full waveform inversion (FWI). "The
expectation is that the resulting improved
velocity model will result in significantly
improved imaging," says Dryer. "The same
principal applies on shore, where new
data, well sampled in offset and azimuth,
is driving interest in FWI to get a more
detailed near-surface velocity model."
New acquisition geometries that result
in significantly larger data volumes have
led to other changes at Fairfield Geotechnologies. The company no longer has
a physical computing center. "It is all
about efficiency and scalability," Dryer
stresses, saying that the move to cloud
computing enables the company to scale
up computer resources on demand.
"We can bring thousands of processors
to bear on raw survey data without incurring the cost of owning and maintaining
the computing technology," Dryer explains.
"The cost is variablized, enabling us to
deliver quantitative interpretation-ready
data much faster and more cost efficiently
than ever before.
The value extractable from the data

American Oil and Gas Reporter - August 2019

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