American Oil and Gas Reporter - March 2021 - 52

pages 52-59_Layout 1 3/12/2021 4:38 PM Page 52

SpecialReport: Resource Science
Spacing tests from offset pilots five
miles away were applied on the eastern
portion of the section. The central and
western pads were downspaced relative
to the eastern pad, with lateral and vertical
spacing lowest to the west. Completion
order varied from east to west across the
section. The eastern and center pads were
interbench zippered with codevelopment
of the Woodford. The western pad was
intrabench zippering with no Woodford
development. A comprehensive gun barrel
view of the full section is pictured in
Figure 1. Wells are colored by completion
order. Red dashed lines denote a zipper
pair. Lateral and vertical well spacing increase across the section west to east.
The 11 wells in the section had an average lateral length of 4,936 feet and averaged 26 frac stages. They averaged
2,175 pounds of proppant and 1,738 gallons of fluid per foot at a rate of 100 barrels/minute. That compares with an average
lateral length of 4,558 feet for the 10 analyzed offset wells. The offsets averaged
24 stages per lateral with 2,334 pounds
of proppant and 2,289 gallons of fluid
per foot pumped at 90 barrels/minute.
Production differences were evaluated
by examining the impact of well spacing/targeting, completion design and interwell
communication on well performance. Although previous offset pilot pads had been
developed with similar spacing and completion parameters, there were significant
differences between average production
profiles, with higher initial production over
180 days observed in the full-section wells.
The results demonstrated that completion design and interwell communication impacted full-section well per-

FIGURE 2
Modeled Fracture Heights across Full Section Targets
70'

940'

Upper
Meramec

Lower
Meramec/
Sycamore

940'

1,020'

formance in three notable ways:
· Interbench codevelopment significantly increased communication across
perceived deterrents to fracture growth.
· Well-to-well communication was
influenced by completion order.
· Aggregate interwell communication
was higher in full-section development
than in pilot pads, which may have contributed to the full section initially outperforming predrill expectations.
The differences in well performance
and well-to-well connectivity carry important implications for operators planning
to use partial spacing tests to develop
multitarget full sections. Specifically,
these observations underscore the potential
for similar completion designs to yield
materially different well performances in
full-section pad development.

0'
66

470'

660

940'

1,320'

6
660

470'

1,130'

1,32

1,320'

52 THE AMERICAN OIL & GAS REPORTER

1
760'

460'

560

860

Well Group
Completion Order

5,280'

Sycamore

Woodford
Top of 3A @9,275'

1,320'

1,130'

940'

Woodford

45'

1,320'

100'

50'

'
470

Lower Meramec
Base of A @9,200'

940'

100'

Full Section Gun-Barrel View

1,320'

125'

FIGURE 1

Upper Meramec
Base of E @9,075'

1,130'

DNA Diagnostics
Subsurface DNA can be acquired from
microbes in reservoir and nonreservoir
rock. These microbes live and proliferate
within primary- and secondary-porosity
intervals, as well as within faults and
fractures. Pore space distribution indicates
that 20% of the upper, middle and lower
members of the Woodford Shale have
pore throats greater than 1 micrometer,
which can be large enough to house microbes. The ubiquity of microbes in the
subsurface makes them an excellent diagnostic tool, and microbial communities
are sensitive to environmental pressures,
chemical gradients, mineralogy and fluid
properties. Over geologic time, even
subtle differences can result in evolutionarily different species.
DNA diagnostics were performed by
comparing DNA markers in produced
fluids ( " sinks " ) with DNA markers along
a cuttings ( " sources " ) baseline. The cuttings baseline was established by collecting
wet well cuttings from the mud shakers
every 15 feet of measured depth. After
collection, cuttings immediately were
placed in chilled coolers to minimize microbial growth from nonsubsurface sources
and shipped overnight to the laboratory
for DNA extraction, amplification and
sequencing. Similarly, produced fluid
samples were collected directly from the
wellhead, placed in chilled coolers and
overnighted to the lab for processing.
Total fluid contribution logs represent
the probability that a given formation is

American Oil and Gas Reporter - March 2021

Table of Contents for the Digital Edition of American Oil and Gas Reporter - March 2021