Summary
Optimum fluid placement is crucial for a successful acid-stimulation
treatment, both for horizontal wells where there is a broad variation of
reservoir properties along the wellbore and for vertical wells with multiple
zones and/or extensive productive intervals. Recently,
distributed-temperature-sensing technology has enabled us to observe dynamic
temperature profiles along a wellbore during and after an acid treatment. This
technology allows us to monitor and evaluate treatments in real time by
capturing a sequence of temperature profiles at different times and evaluating
temperature response to acid injection.
We have developed mathematical models to simulate the temperature behavior
along a wellbore, horizontal or vertical, during and just after an acid
treatment. This approach couples a wellbore model and a near-wellbore thermal
model considering the effects of both mass and heat transfer between the
wellbore and the formation. The models account for all significant thermal
processes involved during a treatment, including heat of reaction, conduction,
and convection. An inversion procedure is applied to interpret the
acid-distribution profiles from the measured temperature profiles.
For horizontal wells, the results indicate that the distribution of
stimulation fluid along a lateral and the effectiveness of diversion processes
during an acid treatment can be quantified in real time using
distributed-temperature measurements. The model shows that the relative
injectivities into different zones can be interpreted from the temperature
response measured during injection. For vertical wells, we have focused on
diagnosing the volume of acid placed in each zone from the flowback temperature
history. During the flowback period, the zones that have taken more acid volume
will show more heating because of reaction and will have higher temperature
when entering the wellbore. This provides a mechanism to quantitatively
determine the acid distribution. The methods developed from this study can help
to diagnose and optimize acidizing design, and improve the efficiency of acid
stimulation.
© 2012. Society of Petroleum Engineers
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History
- Original manuscript received:
9 April 2011
- Meeting paper published:
8 June 2010
- Revised manuscript received:
29 September 2011
- Manuscript approved:
16 January 2012
- Published online:
31 July 2012
- Version of record:
7 August 2012
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