Journal of Canadian Petroleum Technology
Volume 49,
Number 12,
December 2010,
pp. 37-48
Summary
Many hydraulically fractured horizontal wells in shale gas reservoirs have
been observed to exhibit transient linear behaviour. This transient linear
behaviour is characterized by a one-half slope on a log-log plot of rate
against time. This transient linear flow regime is expected to be caused by
transient drainage of low-permeability matrix blocks into adjoining fractures.
This transient flow regime is the only flow regime available for analysis in
many wells.
In this paper, a linear dual-porosity model is used to approximate the shale
gas completions with a horizontal well and multiple hydraulic fractures. Five
flow regions are identified with this model. It seems that field production
data exhibit Region 4 behaviour, which is primarily transient drainage from the
matrix.
However, a skin effect for Region 4 is observed in many wells. This modifies
the shape of the log-log rate plot and the square root of time plot. A new
analytical equation is presented to model the effect of skin on linear flow
behaviour. The resulting curve shapes are somewhat surprising and tend to
explain the early curve shapes of actual wells. A procedure is presented in
this paper to analyze field data.
© 2010. Society of Petroleum Engineers
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History
- Original manuscript received:
24 March 2009
- Meeting paper published:
16 June 2009
- Revised manuscript received:
30 September 2010
- Manuscript approved:
6 October 2010
- Published online:
1 December 2010
- Version of record:
1 December 2010
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