American Oil and Gas Reporter - January 2023 - 74

Tech Trends
and Woodford, which do not yet have
significant refrac activity.
The P50 EUR for the Eagle Ford is
331,199 barrels of oil and 454 million
cubic feet of gas, which represents an
initial production uplift of 308 bbl/d of
oil and 423 Mcf/d of gas. The Eagle
Ford gas window has a P50 EUR of
1.974 Bcf and 198,981 barrels of condensate.
This translates into an uplift of
2.58 MMcf/d and 256 bbl/d of oil. The
P50 EUR for the Haynesville is 4.757
Bcf, or an uplift of 4,809 MMcf/d (94%
of the 5,100 MMcf/d allocated initial
month's rate).
The Permian organic shale uplift used
a cluster spacing versus recovery factor
model that was supported with measured
recovery factors for both legacy and
new wells. The P50 EUR for the Permian
is 473,501 barrels of oil and 1,327 MMcf
of gas, translating into to an initial production
uplift of 609 bbl/d of oil and
1,706 Mcf/d of gas. Actual recovery factors
were estimated in the southern Midland
Basin from wells with mapped OIP
and EUR data by comparing OIP/acre
to EUR/acre. The drainage radius in
acres was assumed to be 330 feet based
on rate transient analysis work that was
part of UL's 2020 HFTCE paper.
The study had 10 wells with average
cluster spacing of 56 feet. This should be
TABLE 1
Summary of Combined Parent Well Refrac and Child Well Protection Uplift
Refrac EURs
and IPs
Oil Reservoirs
Eagle Ford Oil
Permian Oil
Eagle Ford Gas Condensate
Woodford Oil
Gas Reservoirs
Eagle Ford Associated Gas
Eagle Ford Gas
Haynesville Gas
Marcellus Gas
Permian Associated Gas
Woodford Gas
454,736
1,974,142
4,757,002
6,286,853
1,326,750
2,841,812
74 THE AMERICAN OIL & GAS REPORTER
454
2,724
5,100
4,250
1,833
1,768
93.1%
94.7%
94.3%
94.7%
93.1%
94.7%
Refrac EUR
per Well
331,199
473,501
198,981
154,719
Refrac IP
per Well
331
654
275
260
Correction
for
Pre-Refrac
93.1%
93.1%
93.1%
93.1%
Uplift
bbl/d
308
609
256
242
Mcf/d
423
2,580
4,809
4,025
1,706
1,675
10% of
Candidates
1,289
495
261
90
Total bbl/d
1,289
261
37
495
251
Total
Refrac IP
397,220
301,415
66,823
21,668
787,125 493,586 1,280,711
545,382
673,283
177,944
995 4,004,626
844,565
419,648
Total Mcf/d 6,665,449 4,167,267 10,832,716
Total Infill
IP Loss
Refrac
+ Infill
Combined
a good proxy for the basin as a whole
prior to the second half of 2016, since a
major operator (whose practices were
emulated by many other operators) was
using cluster spacing of 60 feet or more.
The P50 recovery factor for these 10
wells was 4.6% (versus 5.3% from the
UL model with 100% cluster efficiency).
The well dataset that was used averaged
1,200 psi perforation friction, so it is unlikely
that the completions had 100%
cluster efficiency. A second finding was
the P50 recovery factor for new closecluster
spacing completions was 13.7%
for a 9.1% expected recovery factor uplift
with a best practices XLE completion.
Applicable To All Areas
Subsequent work in the Eagle Ford
oil window supported the applicability
of both the cluster spacing versus recovery
factor model and the 330-foot drainage
radius. Gas reservoirs in the Eagle Ford
and other areas have wider drainage areas
because of the increased mobility of gas
versus oil in low-conductivity fractures
at the distal extent of the fractures. Radii
of 440-660 feet have been assumed with
reasonable results in several studies in
gas-prone areas. A second difference between
oil and gas reservoirs is the role of
sorbed gas in the gas reservoirs, which
can increase the gas in place by 20%30%.
It can be estimated from total
organic carbon and laboratory data.
For plays without significant activity
or similar recovery factor studies, it was
assumed that the ratio between refrac
EURs and total EURs for the areas with
both would remain relatively constant.
There is an error bar from possible differences
in cluster spacing, but the majority
of the pre-2016 completions had cluster
spacings in the 50-60 foot range and the
expected uplift in recovery factor should
be in the same range. The total EUR
from completions with close cluster spacing
and high loading serves two purposes:
using the above correlation for the areas
without significant activity, and estimating
the potential damage from poor infill
well protection.
The lost production savings value from
a primary well refrac was assumed to be
40% of the P50 new-well EURs for all
areas. This metric involved the use of a
P50 EUR new-well EUR to assess the
lost bbl/d of oil and Mcf/d of gas from
an asymmetric fracture. To accomplish
this, it was necessary to have wells with
close cluster spacing and high proppant
and fluid volumes and adequate producing
time to get a reliable EUR. The period
chosen for this was 2019 since cluster
spacing had converged on 20 feet and
below by then, proppant and fluid volumes
American Oil and Gas Reporter - January 2023

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