Across many shale plays in North America, operators ask why production
performance disparities exist among horizontal wells. For example, even though
drilling and completion practices of a neighboring operator may be mimicked,
significantly different production results are frequently observed. Several
hypotheses have been presented on the subject with little consensus. In most of
these wells, formation evaluation in the lateral section is limited to gamma
ray. Using a single curve to model the structure leads to multiple solutions
with no way to determine which one is correct. Accordingly, large uncertainties
may exist in: 1) determining the relative geologic position of the wellbore, 2)
placing perforation clusters, and 3) selecting the appropriate staging design
and stimulation treatment for the resulting well placement.
To produce wells that perform to their maximum potential, it is
fundamentally necessary to understand both the placement of the lateral in the
reservoir and the placement of the perforations in the lateral. To optimize
these placements, some measurements must be taken in the lateral. Obviously,
the value of understanding where to locate the lateral and the perforations
must be greater than both the direct costs associated with taking these
measurements and the risk weighted costs associated with deploying tools in the
lateral. A way to acquire this information while mitigating many of the
aforementioned concerns is logging while drilling (LWD). Some of the
measurements that LWD can capture along shale laterals include
borehole/azimuthal images, stress, and mineralogy. With these comprehensive LWD
measurements, not only can the captured data be taken for future completion
design and analysis, they can also be used while drilling the lateral to steer
the wellbore towards a desired target more accurately than gamma ray only.
This paper focuses on how lateral LWD measurements impact well
placement, perforation selection, hydraulic fracture stage spacing, completion
design, resultant production, and subsequent economics of horizontal shale
wells. Practical LWD examples from the Eagle Ford and Woodford Shale plays are
presented, along with their impact on the aforementioned subjects.
In this paper principles of using LWD measurements and interpretation in
a field development plan are described, including relating LWD data to
additional functions such as completion design, microseismic hydraulic fracture
monitoring, production monitoring, and production logging. Ideas on how to
optimize the amount and type of LWD measurements are proposed. Lastly, the
paper will examine the impact of LWD measurements on the overall economics of
horizontal shale wells.
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