American Oil and Gas Reporter - July 2019 - 69

SpecialReport: Reservoir Characterization
Spraberry Wells
For the four Spraberry wells, rock
MSE profiles are available for only the
two engineered completions (wells A and
C), as shown in Figure 4. Offset wells B
and D completed with the base line design
were assumed to have no significant differences in rock MSE profiles compared
with wells A and C.
Figures 5A and 5B compare the ISIPs
for both the engineered and base line completions, the first for Pad 1 (wells A and B)
and the second for Pad 2 (wells C and D).
As with the Wolfcamp treatments, no linear
relationship was observed between ISIPs
and rock MSE values in the Spraberry
wells. However, this observation should
not be interpreted to mean that end-ofstage fracture geometry was independent
of near-wellbore rock properties. Instead,
the data indicates that the degree of rock
property heterogeneity among perforation
depths within individual treatment stages
played a role in net pressure development
through its effect on the distribution of
fluid and proppant within perforated intervals.
Increased heterogeneity was assumed
to exist in the base line completion treatments as compared to the data-driven
completions. If the variability in rock
properties is large enough that the distribution of the fluid and proppant favors
only a limited number of perforation
clusters, fracture geometry can be affected.
Reducing rock property heterogeneity
within the perforation clusters for each
stage promotes more equitable distribution
of the stimulation materials and better
fracture height containment, as shown

TABLE 1
Production Results
(Data-Driven Engineered Completions versus Base Line Completions)
Pad

Well

Formation

Completion

Net Days on
Production

Increase (+)
or Decrease (-)

Wolfcamp

Data-Driven

+20.6%

Wolfcamp

Base Line

Wolfcamp

Data-Driven

Wolfcamp

Base Line

Spraberry

Data-Driven

Spraberry

Base Line

Spraberry

Data-Driven

Spraberry

Base Line

by the differences in ISIPs.
Table 1 shows total oil production
during the first 60 days of continuous
production for all eight wells. The percent
changes are the differences between the
total production of the well with datadriven engineered completions and their
respective offsets with base line completions. Spraberry Well A on Pad 1 experienced some difficulties and flow rates
were limited for several days before continuous production operations could be
established. However, cumulative production for Well A after the production
difficulties had been resolved is nearly
identical to Well B.
Despite difficulties encountered with
the field data on the Pad 2 wells, the
results of the study confirm that rock properties computed from data recorded while
the horizontal section is being drilled can
be helpful in evaluating pressure meas-

FIGURE 5B
ISIPs for Pad 2 Spraberry Wells C and D
1,500
Spraberry Well C
Spraberry Well D

1,250

ISIP (psi)

1,000

750

500

Toe

Heel
250

Spraberry Well C
0

+54.1%
-16.0%
+19.4%

urements during stimulation treatments.
The results of the Midland Basin study
provide a clear path forward to improving
future wells by understanding how rock
properties and completion design relate
to fracture height growth. This allows
for a re-evaluation of future drilling targets
and the modification of treatment designs
to maintain the maximum amount of fracture energy within the target zone. It also
will help to provide further evidence that
completions can be improved through
the optimized placement of stage boundaries and perforation clusters.
❒
DUSTY DAVES is senior operations
engineer at Legacy Reserves Operating
LP, responsible for supervising drilling
and completions operations in the Permian Basin. Before joining the company
in 2007, he was a drilling and completions engineer for Mewbourne Oil
Company in the Texas Panhandle and
eastern New Mexico. Daves holds a
B.S. in petroleum engineering from
Texas Tech University.
ROBERT DOWNEY is technical adviser for the Mid-Continent region for
Drill2Frac LLC, specializing in using
drilling-derived rock data to design
staging and perforation strategies for
horizontal well stimulations. Before
joining Drill2Frac, Downey had a 27year career at Schlumberger in production and stimulation engineering
positions, including serving as principal
engineer and interpretation manager
for microseismic services. He holds a
B.E. in mechanical engineering from
the University of Saskatchewan.
JULY 2019 69

American Oil and Gas Reporter - July 2019

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