Integrated Microseismic and 3D Seismic Interpretation
Thomas H. Wilson 1, Ariel K. Hart1, Pete Sullivan2, and Doug Patchen1,3
1Department of Geology and Geography, West Virginia University, 2Energy Corporation of America, 3National Research Center for Coal and Energy
This research effort integrates microseismic data collected
during hydraulic frac’ing operations conducted in a cluster
of horizontal Marcellus wells in Greene County, PA with 3D
seismic data over the area. Microseismic activity is
displayed in the context of subsurface geology using well
log and 3D seismic data. A key goal of these efforts will be
to determine the relationship of microseismic activity to
subtle faults and fracture systems extracted from the 3D
1) Develop a 3D seismic interpretation of an active
Marcellus shale gas development area;
2) Incorporate available geophysical logs and subsurface
data into the geophysical characterization and subsurface
3) Position microseismic events in the subsurface
stratigraphic framework and 3D seismic interpretation;
4) Evaluate relationship between seismic scale fault
networks, other seismic attributes and microseismic
5) Create a workflow you can use and modify for decision
making on placement of future laterals.
High frequency attenuation is commonly observed in wave
propagation through fracture zones and faults. We use
t*attenuation to identify areas of high frequency loss across
windowed regions throughout the 3D seismic volume. The 3D
attenuation volume is then used as an input to a seismic
discontinuity detection process (in this case, Ant Tracking). The
discontinuities (10) fall into two roughly orthogonal trends (~N50E
and ~N40W). The seismic scale faults have roughly N25E trend (11)
that coincides with the trend of local surface anticlines
(Washington and Hundred). The out-of-zone events are observed in
an area where the discontinuities form a nearly-vertical fan-like
cluster (8 and 9) on the northwest limb of the local drag fold. This is
a somewhat unique feature of the area. In addition, we note that
the Marcellus fold and fault in the treatment area die out through
1500’ of overlying strata, whereas fault offsets to the east appear
to continue vertically upward through those overlying strata.
Frequency magnitude plots for two prominent out-of-zone clusters
(12A) yield three b-values. The larger and vertically more extensive
East cluster (12B & C) is localized in the XY plane (12C). Event
magnitudes less than -2 in the East cluster have b-value of 1.61.
The general trend suggests that higher magnitude rupture might be
more likely; however, the frequency of occurrence for the higher
magnitude events drops off more steeply for M>-2, with b-value of
~4. The deeper West cluster has b-value of 5. The high b-value
suggests larger magnitude events are very unlikely in this area.
Events in the East cluster should be subdivided based on depth to
see if the larger magnitude events are stratigraphically restricted.
Fracture systems or mechanical heterogeneity in the shallower
zone may be conducive to failure along larger-area surfaces.
Significant progress toward key deliverables has been made since
our May 1 startup. Development of the data base in an integrated
workstation environment has been completed. Post-stack
processing workflows were developed to help enhance subtle faults
and possible fracture zones in the 3D seismic data set.
Interpretation of those subtle features is underway along with
evaluation of interrelationships between microseismic activity
subtle faults and fracture systems. Our efforts have resulted in two
abstract submissions noted below. No significant obstacles to
continued progress have been encountered.
Hart, A. K., Wilson, T. H., and Sullivan, P., submitted, 3D Seismic Attribute-Assisted
Analysis of Microseismic Events within the Marcellus Shale: for presentation at the
AAPG International Exhibition and Conference, Houston, TX, April, 2014.
Wilson, T. H., Hart, A. K., and Sullivan, P., submitted, 3D Seismic Workflows Developed
to Evaluate Out-of-Zone and Stealth-Zone Microseismic Behaviors: Marcellus Shale,
Central Appalachians, USA: for presentation at the AAPG International Exhibition and
Conference, Houston, TX, April, 2014.
This research is undertaken through the Houston Advanced Research Center
Environmentally Friendly Drilling Program funded through the RPSEA.
Schlumberger Petrel and IHS Kingdom Suite software were used to undertake
much of the analysis. Appreciation is extended to the Energy Corporation of
America for providing 3D seismic, microseismic and well data being evaluated in
this research effort.
Environmentally Friendly Drilling Systems
2013 Year-end Review
In this study we examine interrelationships between 3D
seismic response and anomalous microseismic distribution
observed during hydraulic fracture treatments from a
cluster of Marcellus Shale wells in the Appalachian
foreland area near the west margin of the Rome Trough.
Type log response for the Marcellus in the study area was
developed using a nearby sonic and gamma ray log (1). Log
correlations of marker beds were carried through several
wells in the area of 3D seismic coverage (2). A synthetic
seismic tie (3) provided the basis for seismic interpretation.
Checkshot locations did not consistently bound the shale
section (4). Interval velocities computed from the
checkshot data were anomalously high. A velocity function
was developed independently from the integrated sonic
following the seismic tie. Additional calibration was
obtained by matching depth converted seismic surfaces to
well top picks and geosteering reports from treatment
wells associated with anomalous microseismic clusters (5,
6 and 7).
Seismic data were enhanced for 3D visualization and
seismic discontinuity extraction in the vicinity of the
treatment area using time-variant trace amplitude slicing
and differential attenuation (t*attenuation) computations.
Amplitude slicing uses absolute values of trace amplitude
followed by bandpass filtering in a series of two to three
steps to increase apparent frequency content. The output
retains direct relationship to variations in signal phase and
frequency content through time. The process improves
visualization and interpretation of subtle amplitude and
phase variations related to local structural and
stratigraphic features (8 and 9).
3) Synthetic seismic tie 2) Log correlations: flattened on the top of the Marcellus
1) Type log responses : sonic and γ-ray
4) Checkshot locations relative to stratigraphic markers 5) Depth converted seismic volume using
velocity model derived from synthetic tie
and well top picks
6) Base of the shale/top of the Onondaga
interpreted from depth-converted seismic.
7) Microseismic events shown in depth
relative to the base of the shale section
8) Microseismic events shown on depth
converted seismic display. Line cuts
through microseismic cloud.
9) Interpreted faults along seismic line through the out-of-zone
microseismic cloud. Structures in the shale section overlying the
Marcellus are not unique to the stimulated area.
10) Seismic discontinuities and cluster locations 11) Seismic discontinuities on the Onondaga. Fault intersections are highlighted
12) Gutenberg-Richter frequency-magnitude
plots for two prominent out-of-zone clusters.
-2.6 -2.4 -2.2 -2.0 -1.8
-4500 -4000 -3500 -3000 -2500 -2000 -1500
Out of zone microseismic clusters
-5690 to -4860
lower diffuse cluster
-5690 to -5350
B. C. A.
40 60 80 100 120
Slide Number 1