This paper probes the gauge-placement issue with regard to yielding quality
formation parameters unaffected by wellbore effects. Nonphysical or biased
results may result if the wellbore effects are unaccounted for.
We used a wellbore/reservoir simulator that conserves mass, momentum, and
energy to develop a comprehensive understanding of the gauge-placement issue.
First, we reproduced a field example from a deepwater asset to demonstrate the
simulator’s capabilities. In this example, we matched the bottomhole pressure
(BHP) and pressure/temperature monitored about midpoint of the flow string
during a multirate-test sequence lasting approximately 60 hours. Calculations
show that thermal effects are exacerbated by increasing flow rate and
increasing gauge distance from the perforations.
Second, we performed a detailed uncertainty analysis with experimental
design. Variables included in this analysis were perforation-to-gauge distance,
permeability, geothermal gradient, flow rate, fluid viscosity, thermal
conductivity of annular fluid and formation, and mechanical skin. This analysis
sheds light on relative importance of these variables on our ability to extract
formation parameters. Simple correlations are developed for designing gauge
placement in many environments.
© 2009. Society of Petroleum Engineers
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- Original manuscript received:
17 February 2007
- Meeting paper published:
11 June 2007
- Revised manuscript received:
4 August 2008
- Manuscript approved:
10 September 2008
- Published online:
2 March 2009
- Version of record:
26 February 2009