American Oil and Gas Reporter - November 2018 - 42

Industry In Motion

HFTS Yielding Key Fracturing Insights
By Jordan Ciezobka,
James Courtier
and Joe Wicker
DES PLAINES, IL.-The Hydraulic
Fracture Test Site (HFTS) is a field-based
hydraulic fracturing research experiment
in the eastern part of the Midland Basin
between the Central Basin Platform and
Eastern Shelf. The $25 million research
program fosters collaboration between
experts from the industry, academia and
government in addressing fundamental
questions about hydraulic fracturing behavior within an unconventional resource
development setting.
The principal objectives of HFTS include researching methods to reduce and
minimize potential environmental impacts,
demonstrate safe reliable operations and
to improve the hydraulic fracturing efficiency of horizontal shale wells. The
study has pumped more than 400 frac
stages in 11 long-lateral horizontal wells
drilled in the Upper (six wells) and
Middle Wolfcamp (five wells) formations
(Figure 1), as well as two recompleted
legacy wells.
In addition to collecting comprehensive
field data, approximately 600 feet of excellent-quality, whole core has been obtained by drilling a high-angle slant core
well (SCW) directly through induced hydraulic fractures post-completion at a
central location within the test site. Considered an industry first in the Permian

Basin, the SCW (shown as a yellowblack dotted line at right in Figure 1)
was drilled at an 82-degree inclination
between two adjacent producing wells
within a development spacing configuration in the Upper and Middle Wolfcamp
formations.
Based on observations of the acquired
core, the understanding of hydraulic fracture propagation and effectiveness of
proppant placement is challenging current
thinking. Well interference testing and in
situ reservoir pressure measurements
using bottom-hole gauges in producing
wells and discrete multilevel pressure
gauges in an offset monitor well aid in
understating fracture connectivity and
conductivity over time.
The HFTS is located in Reagan County,
Tx., in an area covered by a high-quality
3-D seismic survey and surrounded by
many producing horizontal and vertical
wells. Several adjacent wells contain
open- and cased-hole petrophysical, production and image logs, as well as whole
cores and sidewall cores. In addition, microseismic and tiltmeter surveys were
collected during the stimulation of all
wells.
The 11 horizontal wells all have extended lateral sections of more than 10,000
feet, drilled from north to south, and approximately normal to the predicted maximum horizontal stress orientation. In
total, more than 400 hydraulic fracture
stages were pumped in the test wells, of

FIGURE 1
HFTS Location in Midland Basin and Site Layout
1

Wind
Direction

2

Air Quality
Station
Water Well
MW Horizontal
UW Horizontal
Slant Core Well

Test
Site

3
4
5

42 THE AMERICAN OIL & GAS REPORTER

which the majority were traced and/or
monitored with advanced diagnostics.
Comprehensive acquired data include
microdiagnostic formation injection tests,
advanced open-hole logs, 110 sidewall
cores, complete (whole) core analysis,
petrophysical evaluation, geomechanical
analysis, petrographic imaging, tracer
analysis, microseismic mapping, tiltmeter
surveys, bottom-hole pressure data, and
multiple pre- and post-treatment crosswell seismic surveys. In addition, air and
water samples were collected before, during and after fracturing to monitor and
assess potential environmental impacts
from the fracturing operations.
At the HFTS, industry partners provide
access to new and existing producing
wells, science wells, and background data
such as 3-D seismic, geomechanical and
petrophysical data. Using existing producing wells for diagnostic instrumentation
and observations in proximity to test
wells brings significant cost savings,
while linking the research and results
with actual production. In addition, industry participation provides early buyin to the program and its results, leading
to early adoption of advanced technologies
and results, which is the most effective
technology transfer mechanism.
Slant Core Well
The SCW was designed to collect
whole core through the stimulated reservoir volume both above and below the
adjacent producing wells from which
the hydraulic fractures originate. About
450 feet of continuous core was recovered
in the Upper Wolfcamp, representing 60
vertical feet of the fractured reservoir at
89 horizontal feet from the nearest completion stage. An additional 150 feet of
core were recovered in the Middle Wolfcamp at 135 horizontal feet from the
nearest completion stage. It showed considerably less fracturing than the Upper
Wolfcamp portion.
Once at surface, gamma ray logging
was conducted to identify the presence
of radioactive tracers pumped during the
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