American Oil and Gas Reporter - August 2022 - 66

SpecialReport: Hydraulic Fracturing Tech
Boosting Recovery Factors
Analyzing refracs in the Eagle Ford
condensate window, the maximum recovery
factor based on Mcf equivalent
observed from the most efficient completions
is about 35%. The combined recovery
factor is calculated from the combination
of the pre-refrac cumulative production
plus the post-refrac EUR. The
environmental, social and governance
benefits and ability to help support U.S.
allies with responsibly produced supplies
open up a plethora of opportunities for
the White House to promote refracturing
as a viable solution. It helps politicians
save face on the ESG front while generating
real returns and filling a growing
void between supply and demand in both
the U.S. and global markets.
Organic shale refracs work primarily
by connecting the fracture network to
rock along the wellbore that the primary
treatment left unstimulated, limiting productivity.
In one study, researchers compared
the permeability of samples of " as
received " core and diagnostic fracture
injection test (DFIT) data on the cored
interval. The as received value was 14
nanodarcies and the post-DFIT value was
27,000 nanodarcies (0.027 md). This suggests
the rock can be stimulated to produce,
and there is minimal contribution from
the unstimulated portions.
FIGURE 1
Eagle Ford Refrac Decline Analysis
Liner refrac December 2017
Initial completion June 2014
100,000
10,000
1,000
100
10
1
Diverter refrac July 2016
This hypothesis was supported by a
field experiment conducted by ConocoPhillips
in the Eagle Ford, in which
a horizontal pressure monitor well was
drilled 70 feet away from an existing
producer that had been fractured several
years earlier. The pressure gauges and
underlying data indicated that only 7.5
feet of lateral interval had any pressure
depletion and that 85% of the 50-foot
cluster spacing had stranded hydrocarbons.
It is worth noting that until mid2016,
the majority of organic shale
completions had cluster spacings more
than 50 feet.
The Eagle Ford alone contains more
than 13,000 wells with these wider spacings.
There are numerous other basins
and plays that also have a great many
wells in this wide cluster spacing category,
including more than 3,000 wells
in the Haynesville and 4,500-plus wells
in the Permian. The expected recovery
factor of a 50-foot cluster spacing is estimated
at 3.5%, assuming a 60% cluster
efficiency without the use of extreme
limited entry (XLE) perforating, which,
as a relatively new technique, was not
implemented in shale plays until 2018.
By using XLE, the P50 post-refrac expected
recovery factor in the Eagle Ford
oil window and Permian Basin is 13.7%,
or 3.9 times the expected recovery from
a wide cluster spacing completion with
60% cluster efficiency, according to industry
researchers.
Eagle Ford Case Study
The economics of tighter spacing can
be demonstrated with a case study from
the Eagle Ford, which demonstrates the
recovery factors for the initial wide cluster
spacing completion versus the post-refrac
performance. The change in the well's
production profile is shown in Figure 1.
In this well, the initial frac treatment
was performed in June 2014 with 67-foot
cluster spacing, 776 pounds/foot of proppant
loading, and 17 barrel/foot of completion
fluid. The ultimate recovery of the initial
frac was estimated at 97,613 barrels of oil
with a negative $2.2 million net present
value, assuming a $6 million authorization
for expenditure for a new well.
These economics assume prices of
$93.63/bbl for oil and $5.59/Mcf for
gas in 2022, $83.59 and $4.45, respectively,
for 2023, and flat $77.28 and
$3.77 for 2024 and beyond. Comparing
this volume with the petrophysical oil
in place (Figure 2) indicates that the
initial frac would recover only 3.0% of
the oil in place. At a 60% cluster efficiency,
the predicted recovery factor
would be 2.2%, increasing to 4.5% at
100% cluster efficiency. When only the
Oil
66 THE AMERICAN OIL & GAS REPORTER
Gas
Water Completions
Monthly Production Volume (Mcf of gas and bbl of oil)
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Jul-2014
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