American Oil and Gas Reporter - January 2019 - 67

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Unconventional Resource Science
FIGURE 3
Microseismic and Pressure-Based Fracture Map Results
Unﬁltered Microseismic Data

Filtered Microseismic Data
2,000

Measurement Result
Distance: 1,209 ft
Azimuth: 587.1" W
East: -1,206 ft
North: -61 ft

-2,000

-1,000

0
East (feet)

the fracture growth on the west side of
the fracture and the green curve plotting
growth on the east side of the fracture.
It is apparent from the pressure-based
fracture map results that stopping the
pumps in the middle of the stage resulted
in stopping the growth of the largest/dominant fracture. Resuming pumping after
a short pause created a diversion effect,
resulting in very limited growth of the
largest fracture. This also indicated that
the pause in pumping was creating nearwellbore complexity.
Case Study Results
Both pressure-based fracture maps
and microseismic data were collected on
the three child wells completed on the
pad. Figure 3 shows a comparison of
pressure-based fracture map and microseismic results. The unfiltered microseismic data measured half-length that far
exceeded the half-length from pressurebased fracture maps. The microseismic
data were filtered to only include events
occurring during the fracture stage and
further filtered to remove microseisms in
the top layers that were believed to be
unconnected with the induced fracture
network.
With this filtering, there is good agreement between the pressure-based fracture
map half-length and the microseismic
half-length (Figure 3), although the microseismic length is generally longer.

1,000

2,000

3,000

-1,000

-500

Asymmetry is reflected consistently between the microseismic and pressurebased fracture maps. Pressure-based fracture maps show the hydraulic fracture
height to be constrained within the target
horizons while the microseismic data
show significant activity in layers both
above and below the target horizons.
Figure 4 compares the microseismic
data with the fracture growth curves computed from pressure-based fracture maps.

East (feet)

500

1,000

1,500

Again, the red and green curves are the
fracture growth rates on the west and east
sides, respectively, of the fracture. The
red (west) and green (east) dots represent
the microseismic events on both sides of
the fracture, plotted as the distance from
the wellbore shown on the right axis.
The microseismic events were separated to correspond with the time the
largest fracture was growing and when
the largest fracture stopped growing. The

FIGURE 4
Fracture Complexity from Pressure-Based Fracture Maps
1,200
6,000
1,000
Treatment Pressure (psi)

-3,000

-500

-1,000

500

North (feet)
1,000

2,000

1,500

3,000

4,000

Measurement Result
Distance: 1,251 ft
Azimuth: 587.2" W
East: -1,249 ft
North: -61 ft

5,000
800

4,000

600

3,000
2,000

400

1,000

200

09:00

10:00

11:00

12:00

JANUARY 2019 67

American Oil and Gas Reporter - January 2019

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