American Oil and Gas Reporter - August 2019 - 65

SpecialReport: Seismic & Geophysics
after delivery of the OBN data. Project
cycle time was reduced by almost half
while delivering greatly improved subsalt
images.
Tailored To Smaller Operators
Lockhart Geophysical Company recently completed a 200 square-mile 3-D
survey in Nebraska that was more than
double the size of any previous project
the company had conducted, according
to Geophysical Technician Carlos Jimenez.
"Typically, we are tailored to the smaller operator/producer in Kansas," he says,
adding that in this case, the client chose
Lockhart for its wired acquisition system.
The client wanted to see the data in real
time because it was more comfortable
with real-time data gathering with our
cabled geophones."
Lockhart began stepping out from
Kansas fairly recently in response to opportunities in Nebraska and Colorado,
namely the Niobrara Shale. In contrast
to Kansas, where drilling targets are relatively simple, shallow conventional geologic formations and roadways are uniformly spaced one mile apart on grids
across flat rural terrain, Nebraska and
Colorado present surveying challenges.
"One recent project was in the hills of
Fremont County, Co., where the terrain
was extremely difficult," Jimenez states.
"We are willing and able to adapt to
survey design challenges as needed with
our wired system."
In Wyoming, Lockhart has multiple
jobs lined up for 2-D cabled surveys with
intersecting lines. "Some operators prefer
shooting 2-D for reconnaissance," notes
Jimenez. "If they see something that
piques their interest, they will order a 3D survey focusing on a particular area."
Lockhart has plans to add wireless
nodal systems in the future, given the advantage the technology has in crew size
and efficiency, reports Jimenez. The company already has tested systems and
achieved a reliability rate exceeding 99
percent. Nodal systems have a battery
life sufficient to last for the duration of
typical surveys conducted for operators
in Kansas, he notes. "We can finish the
job, charge, download data and move on
to the next job."
If the client wants to see some wireless
nodal data in real time, Jimenez says the
company plans to lay out a wired line so
the client can see how the data is affected
by strong winds or any other environmental
conditions. And that, he points out, is the

big advantage of cableless systems. "Nodes
can be completely buried, you can make
them almost disappear," Jimenez comments.
He says the ideal solution for Lockhart
is a true all-in-one node, where no wires
are exposed. When there are no exposed
wires, they are not an attractive nuisance
for cows or other animals to tug on. "We
spend about two hours a day troubleshooting problems that often happen because
wires have been pulled or damaged,"
Jimenez concludes.
More Science Required
Natural gas production from the Marcellus Shale is at record levels, but after
more than a decade of concerted development, operators are beginning to venture
outside the established fairways, according
to Steve McCrossin, president of Precision
Geophysical in Millersburg, Oh.
"With known sweet spots getting drilled
up, operators are stepping out of their
comfort zones and moving away from
the core, which requires more science,"
he states, noting that geologic conditions
and reservoir properties can change dramatically from one part of the Marcellus
play to another. "Operators are relying
on high-resolution seismic to better understand noncore areas and properly define
subsurface features for drilling hazard
identification and derisking."
Precision Geophysical maintains two
crews equipped with the ARAM Aries™
24-bit system and Geospace Sensors'
GS-32CT™ high-frequency geophones
for both 2-D and 3-D recording with

In late July, one of Precision
Geophysical's two seismic
crews was acquiring a proprietary 3-D survey in the
Utica Shale in Ohio, while the
other crew was shooting a
proprietary 3-D survey in the
Marcellus Shale in Pennsylvania. One of the primary applications of 3-D in the
Marcellus and Utica is
geosteering laterals 'in zone'
all the way to total depth.

either cabled or cable-free (or both) acquisition methods. In mid-July one of
the crews was working a project in the
Utica Shale in Southeastern Ohio, and
the other was working on a Marcellus
project in Pennsylvania. "Both are proprietary 3-D shoots for oil and gas companies," McCrossin reports.
Like other horizontal resource plays,
one of the primary applications of 3-D in
the Marcellus/Utica is geosteering laterals
to total depth. "In the past, operators
have found that horizontal wells often
drilled in and out of zone," he explains.
"The uniqueness of 3-D seismic data,
combined with logging-while-drilling
data acquired at the bit, lets directional
drillers keep the drilling assembly in zone
all the way to planned TD."
According to McCrossin, staying within
the targeted zone is especially critical given
the fast penetration rates that have become
typical of Marcellus/Utica drilling, with
operators regularly reporting daily horizontal
footage rates of 4,500 or more. Of course,
when drilling a mile of rock every 24 hours,
drifting out of the target window for even
5-10% of the time can mean hundreds of
feet of nonproductive lateral section.
"Fast drilling times have become routine for many Appalachian operators,"
McCrossin comments. "Using seismic
data for geosteering lets them achieve
both high well productivities and high
levels of horizontal drilling efficiency."
Marcellus/Utica surveying challenges
are related largely to the fact that the
region is both heavily populated and has
challenging terrain, McCrossin says. "Be-

Knox County Ohio

AUGUST 2019 65

American Oil and Gas Reporter - August 2019

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