American Oil and Gas Reporter - January 2015 - 105

FIGURE 7

FIGURE 6

B-Values for Post-Injection,
Injection and Hydraulic
Fracturing Datasets

Standard SNR Deviation of Events During (Blue)
And After (Red) Injection
220
Std of SNR during injection
Std of SNR after injection

4.0

200

180

3.5

Post-Injection Events
b=-1.15

160

3.0

120

# Stage

seismic techniques used to monitor hydraulic fracturing, she took a new role
as a technical adviser to the processing
team at Magnitude. Rebel holds a Ph.D.
in earth sciences from the University of
Nice in France.

Log10 of N Events with m³m

140

2.5

2.0

1.5

1.0

0.5

ALICE
GUEST

Alice Guest is geomechanics consultant at Magnitude, a Baker HughesCGG joint venture for unconventional
reservoirs, in Calgary. She is working
primarily on integrating microseismicity
into geomechanical, reservoir and completion models. She began her career
15 years ago as a geomechanical modeling and microseismicity interpretation
researcher in the Geophysical Institute
at the Czech Republic, and then the
University of California, Los Angeles;
and the California Institute of Technology.
Guest applied her knowledge to hydraulic
fracturing problems during her experience at the University of Calgary, and
at ESG Solutions and CGG. She holds
a Ph.D. in geophysics from Charles
University in the Czech Republic.

ESTELLE
REBEL

Estelle Rebel is a geophysical adviser
for Magnitude. She has 10 years of experience in research and development
for seismic acquisition and processing.
After working on improving the micro-

0.0
-2.5

SEAN
BAILLY

Sean Bailly is a microseismic processor for Magnitude in Calgary. He began
his career in marine acquisition as a
seismic observer for Wavefield-Inseis,
before transitioning to onboard processing for CGG. Bailly joined the surface microseismic division at CGG when
it started in 2011. He holds degrees in
geophysics and physics from the University of Calgary.

JELENA
KOSTADINOVIC

Jelena Kostadinovic is a microseismic
processor for Magnitude. She began
her carrier at CGG when the company
was established in 2011. She holds a
B.S. in geophysics from the University
of Belgrade in Serbia.

Hydraulic Fracture Events
b=-1.88

Injection Events

-2.0
-1.5
-1.0
Psuedo Magnitude (m)

-0.5

post-injection events (Figure 7). It is obvious that b-values were distinct for injection versus post-injection events. Additional data were added to include only
events related to the propagating hydraulic
fractures, and excluded events related to
reactivating previous fractures. The bvalue for this dataset was even more distinct from post-injection events.
As opposed to post-injection events,
which were characterized by relatively
low b-values, the microseismic events
recorded during injection exhibited relatively high b-values. The higher range
and higher levels of SNRs (magnitudes)
are signs of pre-existing structure reactivation, which is in overall agreement
with conclusions from the microseismic
and geomechanical analyses. Increased
event frequency toward the end of injection
can be explained by the fact that some
pre-existing fractures had been intersected
during injection.
The dataset evaluated in this study
provides outstanding examples of how
creating hydraulic fractures and reactivating pre-existing structures have clear
microseismic signatures that can be used
as a learning set to develop techniques.
The integrated study combining microseismic, geomechanical, and engineering
analyses improved the operator's understanding of well stimulation, and the
results have had an important effect on
predicting well productivity.
Ì
JANUARY 2015 105

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