Deploying Wireless Seismic
Recording Systems for Real-time
Monitoring and Analysis of
Hydraulic Fracturing Projects
D.B. Crice & M. Lambert* (Wireless Seismic Inc.)
R. Evans & P. Morton (MicroSeismic Inc.)
The need for real-time microseismic
• There are markedly different logistical requirements for Hydraulic
Fracture Monitoring projects than for traditional active reflection
seismic projects.
• Projects need to be coordinated with frac job.
• Ease of deployment and retrieval of the system is paramount to
ensure efficient and flexible operations.
• Results often need to be delivered as soon as possible during or after
each frac.
• Logistics of a wired system can be challenging with surface access
restrictions, natural topography and structures such as rivers,
highways, and fences.
The need for real-time microseismic
• Since real-time processing and analysis of the recorded passive
seismic data is often a HFM requirement, the acquisition system has
to be able to deliver continuous and uninterrupted data from each
station.
• Data can be processed in real-time allowing on-site frac engineers to
view the results at the time of the frac. This provides them with
actionable information with which they can diagnose and quantify
the efficacy of each stage.
• In this poster, we introduce a large-scale wireless and cable-less
seismic recording system for rapid and cost-effective deployment
with real-time data streaming for in-field processing and analysis.
The advantages of the wireless and cable-less system and the benefit
to clients from the availability of real-time results will be discussed.
• Accurate, usable microseismic data
recorded during hydraulic fracture
treatments is critical for successful
monitoring of the frac, yielding results
that include an understanding of the
fracture height, half-length, and azimuth.
• Given the immediacy of the operation,
there is no opportunity to reacquire
data.
• The data acquisition system employed
for surface microseismic has to be
reliable, field deployable under a variety
of conditions, and capable of delivering
streaming data continuously during the
frac operation.
• The system must also perform diagnostic
checks during the deployment and the
frac job, as well as adjust for any
problems.
• Field test of wireless
seismic equipment, set
side-by-side with a
cabled system.
• Background noise was
measured for each
system for 24-hours
and plotted.
• Resultant plots from
the wireless and cabled
systems showed
comparable noise
response.
• The wireless system
proved to be less
susceptible to section
drop-outs due to
severed cables (caused
by wildlife, livestock,
vehicles, equipment,
etc.).
Screen capture showing the status of each acquisition channel,
microseismic events, and a real-time noise monitor for the array.
How can thousands of radios to talk to the
central recorder simultaneously? At low power?
• Make each radio a relay.
– Units only need to communicate by one group
interval.
– Data is passed from unit to unit until it reaches
the backbone.
– The backbone carries the data to the central by
high-speed link or fiber optic.
The lack of cables means:
• During layout, the capability to
skip over surface hazards and
obstacles is extremely
advantageous.
• Surface obstructions such as
rivers, lakes, roads, railroad
tracks, etc. can severely hinder
optimal array design and data
acquisition.
• Permit restrictions can be
mitigated or avoided altogether
by “jumping over” these
obstructions.
• In this figure, several impassable
areas (yellow boxes) associated
with a river did not affect the
shape and arrangement of the
arms of the array.
Individual traces of monitoring data are sent from each array station to
the recorder, quality checked, and saved on a Network Attached Storage
(NAS) device. From the NAS, seismic data are continually transferred to
the Graphics Processing Unit (GPU). Preliminary trace processing is
performed before the application of the imaging algorithm.
Results delivered to the user in near real time
• Visualization images can be broadcast live on the internet to any
interested parties through web based video conferencing
applications.
• The images can also be relayed back to the recording truck, frac van,
or even to smart phones, tablets, or PDAs. The entire process
generally takes 5 to 10 minutes after the event occurrence.
• Central to the ability to image microseismic activity in real-time is the
imaging algorithm, (Thornton, M.P, Eisner, L., 2003) using a traveltime table constructed from an appropriately calibrated velocity
model.
• This velocity model can also compensate for anisotropy observed in
the local geology (Eisner, et al., 2011). The technique employs beam
steering to gather and sum the seismic data input and can detect
microseismic event hypocenters with high accuracy.
Regulatory Trends Toward
Real-Time Monitoring
• UK exploration resumes with new controls to mitigate risk
– Seismic monitoring must be carried out before, during, and after
hydraulic fracturing.
– A new traffic light system to categorize seismic activity.
– Trigger mechanism will stop hydraulic fracturing operations in certain
conditions.
• DNV launches global recommended practice for shale gas risk
management
– Draft standard for shale gas development and operations.
– Includes requirement for real-time microseismic monitoring before,
during, and after hydraulic fracturing.
Frac Monitoring Project Example
• Shown here are partial results
from a project in a multi-well
field (Kratz, et al., 2012).
• The HFM data were collected
with a surface array without
real-time processing.
• Analysis of this section of the
well reveals a linear trend of
microseismic events (shown
in blue) far from the
treatment well.
• Results indicate that
treatment fluids leaked into a
natural fault in the reservoir.
• Real-time monitoring could have revealed the far afield events during
pumping; allowing the operator the option to change the pumping plan.
Real-time monitoring offers the opportunity to
change fracturing operations as a result of the
reservoir’s response to treatment
• Determining overall frac effectiveness:
– Real-time monitoring can determine the effectiveness of treatments
on individual stages and show that stimulation has achieved design
targets saving resources.
• Changing fracture treatment parameters:
– Fracture treatment parameters can be changed from stage-to-stage.
Corresponding changes in the microseismic response can be used to
identify optimum stage spacing and perforation gun arrays as well as
determine optimum fluid volumes, rates and proppant.
– Real-time provides preliminary microseismic results while the field
crews are still on site enabling on-demand program changes. This can
reduce overall project cycle time significantly.
Real-time monitoring offers the opportunity to
change fracturing operations as a result of the
reservoir’s response to treatment
• Ensuring activity stays within zone:
– In the Fort Worth Basin in the southern USA, real-time monitoring can
be used to detect activity breaking out of the Barnett Shale into the
underlying, water charged, Viola or Ellenberger carbonates.
• Identifying Geohazards:
– Sub-seismic faults can be reactivated during frac operations. If fault
reactivation occurs, the stimulation may be directed away from the
reservoir objective resulting in little production.
• Mapping Induced seismicity:
– Real-time monitoring can be used to detect microseismic build-up to
larger seismic events. Identification of precursor seismicity can allow
an operator to change fracturing parameters (e.g., pressures, flow
rates) or to terminate a stage entirely to avoid initiating larger events.
References
• Eisner, L., Zhang, Y., Duncan, P., Mueller, M.C., Thornton, M.P., & Gei, D,
2011, Effective VTI anisotropy for consistent monitoring of microseismic
events: The Leading Edge, 30, no.7, 772-776.
• Kratz, M., Hill, A., &Wessels, S. (2012). Identifying Fault Activation in
Unconventional Reservoirs in Real Time Using Microseismic Monitoring.
SPE Unconventional Resources Conference, Extended Abstracts, SPE
153042.
• Thornton, M.P, Eisner, L. (2003). U.S. Patent No. 7,978,563. Washington,
DC: U.S. Patent and Trademark Office.
• UK Controls www.shale-gas-information-platform.org/areas/news/detail/article/ukexploration-resumes-with-new-controls-to-mitigate-seismic-risks.html
• DNV Standard
www.dnv.com/press_area/press_releases/2013/dnv_launches_global_recommended_practi
ce_for_shale_gas_risk_management.asp?goback=%2Egmr_2241563%2Egde_2241563_mem
ber_210549656