American Oil and Gas Reporter - PBIOS 2014 Official Program Guide - 179

Permian Basin Reports
Upstream

In conjunction with post-job fracture
modeling and open-hole logging data, optical data successfully defined the effectiveness of completion and stimulation operations in the Permian Basin well. A postjob fracture modeling was performed using data acquired by fiber optics to constrain the model, and open-hole logging
data were compared with the distributed
optical results. Distribution of fluid along
the near-wellbore area was analyzed using DTS results to define hydraulic fracture height growth.
The post-job fracture model was compared with the DTS fracture height estimates. If a large discrepancy was observed
between these two values, the post-fracture model was revisited to assess whether
other interpretations of the model were reasonable.
Vertically oriented treatment wellbores have been used in the Permian
Basin to simultaneously target several
stratigraphic hydrocarbon-bearing layers. As the development of unconventional resource plays has progressed in the
basin, it has become common to apply
tools such as hydraulic fracture models,
chemical tracers, production logging and
microseismic mapping to improve the
understanding of completion effectiveness
and reservoir drainage patterns. The primary idea is to characterize the placement
of fracture fluid within the target intervals,
and to determine which intervals/fractures
provide the greatest recovery in relation to
total wellbore production.

ing stimulation fluid and optical data to
confirm the post-fracture model height or
indicate that more modeling should be performed. Once confident stimulation data
were processed and reviewed, the results
could be related to the production data acquired by optical fiber.
While this article focuses on stimulation monitoring, optical data were captured
continuously from the beginning of the first
treatment stage through the first three
months of production, following completion of the final treatment stage. Because
the fiber cable is installed permanently behind casing, production results can be acquired at any time throughout the well's
life cycle. The completion effectiveness
and incremental production of each interval then can be quantified and correlated
to logging and fracturing results.
The customized optical cable was deployed and cemented behind casing one
joint from the bottom of the wellbore to
the surface. The well was completed in 11
fracture treatments using plug-and-perf
techniques. A solid bridge plug provided
tubular isolation between intervals. The

Midstream

Downstream

fractures targeted formations ranging
from the Mississippian and Atoka carbonate to the Spraberry. All 11 stages used 20
feet of oriented perforations with varying
separation between clusters. Perforation
phasing was set to 0 degrees and oriented 180 degrees away from the optical cable.
The deeper intervals were stimulated
with slickwater, placing 100,000-120,000
pounds of proppant per stage. The shallower intervals were treated with a cross-linked
gel fluid system, placing 120,000-150,000
pounds/stage.
DTS Analysis
Temperature in the immediate vicinity
of the borehole is measured using a fiber
optic cable, and the temperature profile derived from DTS can monitor fluid movement within the wellbore during fracturing
treatments and production. DTS analysis
and interpretation are based on comparing
temperature changes along the wellbore to
predict areas of fluid flow and reservoir entry. Post-treatment recovery to geothermal
temperature is used to predict the injection

FIGURE 1
DTS Data Collected for All 11 Stages

Fiber Optic Profiling
However, the challenge in using these
diagnostic technologies for production
analysis and fracture fluid placement is that
they provide a single "snapshot" in time,
and do not provide diagnostic value of
changes over an asset's life cycle. To circumvent these drawbacks, a permanently deployed fiber optic cable was placed
behind the production casing and cemented in place to provide distributed thermal and acoustic profiles throughout the
stimulation, completion and production
processes.
Fracture modeling was performed as a
design technique to understand the total
reservoir coverage before stimulation.
The post-fracture model was developed to
match the pressure response while injectOCTOBER PBIOS 2014 179

American Oil and Gas Reporter - PBIOS 2014 Official Program Guide

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