Deploying Wireless Seismic Recording Systems for Real-time Monitoring and Analysis of Hydraulic Fracturing Projects

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2 Δεκ 2013 (πριν από 3 χρόνια και 6 μήνες)

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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.)



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.


R
esults
often need to be delivered as soon as possible
during
or after
each frac.


L
ogistics
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.

The need for real
-
time microseismic


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
travel
-
time
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/uk
-
exploration
-
resumes
-
with
-
new
-
controls
-
to
-
mitigate
-
seismic
-
risks.htm
l



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