American Oil and Gas Reporter - January 2023 - 60

TABLE 1
Design
A
B
C
D
E
F
G
Rate
90
90
80
80
90
100
100
Summary of Completion Designs Tested in Wolfbone Field Study
Tracers
Fluid
(bbl/ft)
70
85
85
70
80
70
85
based on rock properties derived from
drilling performance data to calculate
mechanical specific energy (MSE) and
identify areas of depleted fracture networks
(DFNs). The process entailed calculating
MSE, which was then further refined to
eliminate the effects of constantly changing
drilling efficiency, creating a measurement
known as " rockMSE. " This value is
closely related to the unconfined compressive
strength of the rock along the
lateral. RockMSE was used to select
stage boundaries and determine the best
locations to place perforations.
Figure 2 shows depletion anomalies,
rockMSE variation, gamma ray and mud
log lithology along the infill well lateral.
Depleted fractures are colored by level
of confidence, with light red signifying
low, red signifying high and dark red
corresponding to very high confidence.
Multiple depletion signatures are observed
along the lateral with a maximum depletion
of 1,500 psi, although most anomalies
are about 500 psi of depletion
The drilling data was further refined to
identify areas of localized depletion around
Proppant
(lbs/ft)
1,700
1,900
1,900
1,700
1,900
1,700
1,900
Engineered
Stages
1, 2, 3, 14, 15,
16, 17, 18, 19
4, 5, 6, 7
8, 9, 10
11, 12, 13
20, 21, 22
23, 24
25, 26
37, 38, 39,
40, 41, 42
producing DFNs. DFN anomalies require
more energy to drill through because of
lower reservoir pressure as manifested by
higher rockMSE without an apparent
change in lithology or other drilling artifacts.
To account for the inherent uncertainty in
identifying depletion using drilling data
(specifically in areas with a low signal-tonoise
ratio), anomalies were ranked by
degree of confidence, since they may be
produced by multiple factors and are not
always indicative of a depleted fracture.
The goal of stage boundary placement
in the engineered design was to avoid
large-scale changes in mechanical rock
properties within each stage. Cluster locations
were then selected using an automated
algorithm that placed perforations such
that each cluster was in similar rock while
also balancing cluster-to-cluster distance
and avoiding areas of excessive rock heterogeneity.
This allows the greatest opportunity
to achieve uniform distribution of
completion slurry across all perforations.
Clusters were omitted in a few selected
stages if depleted fracture networks were
identified due to DFN anomalies that
Geomoetric
Stages
30, 31, 32
33, 34, 35, 36
27, 28, 29
(Engineered Stages)
4,500, 4,600
4,500, 5,000
5,000, 8,300
8,300
3,300
7,000
3,500
Tracers
(Geometric Stages)
3,400
6,400
5,100
8,400, 4,800
were likely areas of depletion on either
side of the fracture, which could serve as
high-permeability pathways for rapid
fluid migration toward the depleted region
near the parent well.
Stages 27-42 were perforated using
geometric positioning of the perforations
with the following parameters: average
stage length of 172 feet, average cluster
spacing of 18 feet, 10 clusters per stage,
and five shots per cluster on 60-degree
phasing. No effort was made to honor
calculated rockMSE in the geometric segment
of the infill well. One DFN anomaly
flagged as high confidence was avoided
by omitting a cluster in one of the stages
perforated with the geometric design.
Twelve unique chemical tracers were
pumped into the infill well, and produced
fluid samples were collected from both
the primary and infill wells. The samples
were analyzed in the lab for tracer type
and concentration over time.
Microseismic Monitor Wells
Two drilled but uncompleted horizontal
wells were used as microseismic monitor
FIGURE 2
Depletion Anomalies, RockMSE Variation, Gamma Ray and Mud Log Lithology along the Infill Well Lateral
Depleted
Fractures
Rock
MSE
Measured
Depth
Gamma
Ray
Mudlog
60 THE AMERICAN OIL & GAS REPORTER
9,000
10,000
11,000
12,000
13,000
14,000
15,000
16,000
American Oil and Gas Reporter - January 2023

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