Summary
This paper presents a semianalytical model for transient flow into multiple
vertical wells producing from a porous medium containing randomly distributed
discrete fractures. Both vertical openhole wells and hydraulically fractured
vertical wells are considered. The semianalytical model simulates pressure and
pressure-derivative characteristics of wells and flow distribution along and
through both the natural and the hydraulic fractures.
The study shows that single or multiple isolated natural fractures yield
negative pseudoskin factors in vertical wells near isolated fractures. The
negative pseudoskin factor is a function of fracture conductivity, density,
length, distance from the wellbore, and azimuth.
Using the model, we demonstrate that the shape of the pressure derivative is
related to fracture distribution. The results of this study indicate that the
conventional double-porosity analysis to predict the storativity ratio of a
naturally fractured system is not reliable. Also, the displacement between two
semilog straight lines is not necessarily a good indicator of the storativity
ratio.
Introduction
The main objective in this study is to develop a semianalytical model to
simulate the flow inside a homogenous porous medium containing randomly
distributed and unconnected fractures. Once such a model is available, the
effect of isolated fractures on the pressure-transient behavior of producing
wells may be investigated. In the current literature, only a few analytical
studies focus on the effect of stochastically distributed natural fractures on
well performance. To the best of our knowledge, the literature lacks a model to
simulate the transient flow toward a system of vertical open holes and
hydraulically fractured wells producing from a porous medium dissected by
randomly distributed but disjointed natural fractures. This study offers such a
model.
© 2009. Society of Petroleum Engineers
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History
- Original manuscript received:
14 February 2007
- Meeting paper published:
16 April 2007
- Revised manuscript received:
5 May 2008
- Manuscript approved:
8 May 2008
- Published online:
1 June 2009
- Version of record:
1 June 2009
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