American Oil and Gas Reporter - July 2018 - 83

SpecialReport: New Tech & Geosciences

3-D Surveys Focus On Resource Plays
By Kari Johnson
Special Correspondent
Successfully developing tight oil and
shale gas plays requires the right technology, knowledge, capital and assets.
Geophysics is playing a role in all of
those areas by helping operators achieve
a better understanding of a multitude of
reservoir properties that can influence
productivities and recovery rates, thereby
leading to better decisions about where
to drill and how to optimize completion
designs to maximize every dollar invested
in unconventional resource plays.
Nancy House, principal scientist at
Integrated Geophysical Interpretation and
president of the Society of Exploration
Geophysicists, says resource plays offer
an exciting opportunity to expand the
role of geophysics across exploration,
drilling, completion and production workflows. "As operators become more and
more familiar with the unique challenges
of unconventional formations, and as they
see what advanced geophysical solutions
can do in these plays, they are gaining a
new appreciation for the contribution that
geophysics can make to bottom-line success," she states.
When resource plays began making
headlines more than a decade ago, tight
rocks were a mystery in many respects,
behaving very differently from conventional reservoirs, she reflects. "Operators
in Wyoming started finding these apparently unbounded gas deposits," explains
House. "Every time they drilled a new
well, no matter how close or how far
away from existing wells, it still seemed
to encounter virgin pressure in a lot of
zones and permeability could be increased
with hydraulic fracturing."
This initially led to what House calls
"a bit of magical thinking" that unconventional assets could be developed in
cookie-cutter fashion with little understanding of the subsurface. Reality soon
set in, however, and oil and gas companies
began developing multidisciplinary teams
of geoscientists and engineers to leverage
geophysics to identify the rock properties,
fluid characteristics and natural fracturing
features that have proven critical to optimizing well performance.
House says the challenges of unconventional reservoir development are
prompting the geophysical industry to

apply everything it has learned through
decades of experience in conventional
reservoirs as well as the relatively new
knowledge gained in unconventional
plays-from amplitude-versus-offset and
rich-azimuth data acquisition techniques
to advanced processing algorithms and
borehole microseismic imaging-to determine location, orientation and extent
of hydraulic fractures, mechanical rock
properties, effective well placement, optimal drilling depths, the most (and least)
favorable areas to place hydraulic fracturing stages, fracturing effectiveness,
etc., in tight rocks.
The next step in the evolution of geophysics is the routine application of artificial intelligence and machine learning
not only in seismic acquisition and processing, but especially in interpretation,
House predicts. "We have always had
huge datasets and synthesizing it has always been an equally huge task," she
says, noting that with the aid of technologies such as AI, statistical analysis,
principle component analysis and selforganizing maps, geophysicists can do
more in-depth and thorough analyses in
much less time.
"Artificial intelligence and machine
learning have sufficient maturity and appeal that SEG is coordinating a multiplesociety conference devoted to these technologies," House remarks. "One need
only look at the list of upcoming workshops on SEG's calendar to see how unconventional reservoirs and advanced
technologies are impacting geophysics."
Along with workshops on traditional
geophysical topics such as marine 3-D
seismic acquisition and land data processing, she says SEG also is offering
workshops on the value of geophysics
throughout the unconventional asset lifecycle and applications of AI and machine
learning in the geosciences. "It is a new
world," House remarks.
At the same time, she adds that SEG
also is sponsoring initiatives to better
connect geophysics with engineering and
management, including a special session
on the business of geophysics at its 2018
annual conference, scheduled for Oct.
14-19 in Anaheim, Ca. "Geophysics has
a pivotal role in oil field economics,"
House concludes. "That role has been
driven in no small part by the multidisciplinary challenges of unconventional

plays, and requires geophysicists to be
active members of asset teams along with
drilling, completion and production engineers."
High Channel Counts
Dawson Geophysical has been busy
in the Midland and Delaware basins in
West Texas during the past year, acquiring
surveys for operators as well as multiclient
data providers, reports Chief Executive
Officer Steve Jumper. Projects in these
sub-basins of the greater Permian Basin
tend to be larger in scope than survey
projects in many other U.S. basins, he
notes.
"It is not uncommon to have 20,00025,000 recording channels on a project,
with our largest survey having 30,000
channels," Jumper says.
The high channel counts are driven
by project size plus the need for widerazimuth and full offsets. "That requires a
lot of channels, particularly when you
are increasing the coverage density of
those channels and sources," Jumper explains, adding that there is room for even
higher-density recording in the future to
get better subsurface image resolution.
Dawson also has recorded multicomponent channels in West Texas using conventional vibrators and receivers for both
standard and converted-wave seismic
data. The intent is to give operators a
better understanding of rock properties
and reservoir properties. Jumper says that
the company has kept a large three-component crew busy for several years. "I
expect to see increases in both 3-C data
acquisition and channel density in the
coming years," he offers.
Dawson has a mix of proprietary and
multiclient projects acquiring both standard
compressional and multicomponent data,
but he says multiclient data providers
have been the drivers of the most recent
activity. "It is a scale and scope issue,"
observes Jumper. "In some places, there
are such interlocked acreage areas that
multiclient studies provide the best coverage for everyone."
In the complex geology of West Texas,
3-C surveys are giving operators invaluable
insights on the properties of stacked
multibench zones and fracture orientations-key issues in Permian tight oil
plays. "The Midland and Delaware basins
have historically been a little tougher
JULY 2018 83
American Oil and Gas Reporter - July 2018

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