American Oil and Gas Reporter - August 2020 - 47

pages 44-51_Layout 1 8/12/2020 10:40 AM Page 47

three wells (9,000 barrels of slickwater,
82,000 pounds of 40/70 white sand and
330,000 pounds of 100-mesh sand per
stage). The only design difference between
the wells was the pump rate. Because the
AC2H and AC3H are closer to the parent
well, they had a designed pump rate of
80 barrels/minute versus 100 bbl/m for
AC4H.
Pressure communication on this pad
was very strong between the Wolfcamp
A and B. The combination of tensile and
fluid communication signals indicated
significant height growth upward in a
vertically stacked pair of wells (AC2H
and AC3H). The order of operations impacted the fracture growth of all three
child wells.
Leading the zipper treatment sequence
with the lower wells resulted in greater
fracture height growth toward the parent
well and shorter half-lengths in both of
the nearest child wells. Leading with the
upper well mitigated parent-child well
communication, and all three child wells
experienced greater horizontal fracture
growth and less total height. With realtime feedback, the operator optimized the

completion design, limited overlap between
the developed fractures, and mitigated
damage to both parent and child wells.
Surface Pressure Data
Surface pressure on the parent well,
AP1H, increased 600 psi while the three
child wells were being completed. The
largest pressure signal magnitude within
a stage was 400 psi (AC2H stage 6 and
AC3H stage 27).
The colored circles in Figure 1 indicate
the classification of the pressure signals
observed from AP1H while each stage
of the child wells was being fractured.
The radius of the circle is proportional to
the logarithmic pressure change magnitude
recorded at each stage. The red boxes
denote the stages not included in the
analysis, including the loss of 16 total
stages of pressure signals (AC2H stages
11-13, AC3H stages 2-6 and AC4H stages
10-17) related to pulling an electrical
submersible pump from AP1H.
The poroelastic signal responses were
divided as either compression signal (positive) or tensile (negative) pressure, and
the recorded data was binned into four

categories according to the nature of the
parent-child pressure communication,
ranging from severe to null:
· Direct communication (fluid moving
through a hydraulic channel connecting
the child and parent), which creates an
instantaneous pressure increase and a
significant pressure buildup trend, followed
by pressure leak-off at the end of the
stage;
· Fluid migration, identified by a
smooth and gradual pressure increase
during treatment that continues into the
shut-in period before eventually decreasing
as excess pore pressure dissipates into
the reservoir and fracture system;
· Stress shadowing (poroelastic response), characterized by compressive
stress increasing proportionally with respect to the dominant hydraulic fracture
in the child treatment stage and immediate
elastic spring-back "shadowing" at the
end of the stage; and
· No observable signal, which can
be caused by a large horizontal distance
between wells, complete pressure isolation
between benches or understimulation.
The surface pressure signal magnitudes
observed at AP1H while fracturing the
child wells were much greater for AC2H
and AC3H than were those of AC4H. All

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