Summary
Horizontal wells with hydraulic-fracture treatments have proved to be an
effective method for developing unconventional oil and gas reservoirs. During
the past several years, fracturing methods have evolved and improved rapidly;
however, there still exist many uncertainties in fracture design. Several
fracture-diagnostic techniques have been developed to improve the understanding
of the fracturing process. In this study, after reviewing the application and
limitations of the current fracture-diagnostic techniques, we describe the
application of distributed temperature-sensing (DTS) technology as a
complementary tool for real-time fracture diagnostics. DTS technology has
enabled us to observe the dynamic-temperature profile along the wellbore during
the treatment. However, quantitative interpretation of dynamic-temperature data
is very challenging and requires in-depth mathematical modeling of heat and
mass transfer during the treatment.
We have developed a thermal model to simulate the temperature behavior along
the wellbore during the treatment, as well as during the shut-in period. This
model takes into account the effect of all significant thermal processes
involved, including conduction and convection.
Examples are presented to illustrate how this model can be applied for
fracture stimulation diagnostics. Estimation of the fracture-initiation points,
number of created fractures, and distribution of stimulation fluid along each
isolated zone are the problems for which DTS technology can help obtain
answers. The effectiveness of isolation can also be diagnosed by DTS technology
because the heat-transfer mechanism changes when convection caused by leaking
in isolation occurs. This information can be used for more-accurate fracture
modeling and better estimation of fracture conductivity and fracture geometry
and, therefore, to optimize future treatments and also to evaluate the well
performance.
© 2012. Society of Petroleum Engineers
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History
- Original manuscript received:
19 August 2011
- Meeting paper published:
16 November 2011
- Revised manuscript received:
5 January 2012
- Manuscript approved:
21 June 2012
- Published online:
1 November 2012
- Version of record:
13 November 2012
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