Summary
The conductivity of an acid-etched fracture depends strongly on void spaces
and channels along the fracture resulting from uneven acid etching of the
fracture walls. In this study, we modeled the deformation of the rough fracture
surfaces acidized in heterogeneous formations based on the synthetic
permeability distributions and developed a new correlation to calculate the
acid-etched fracture conductivity.
In our previous work, we modeled the dissolution of the fracture surfaces in
formations having small-scale heterogeneities in permeability. The
characterization of the correlated permeability fields of rock includes the
average permeability, normalized correlation lengths in both horizontal and
vertical directions, and normalized standard deviation. These statistical
parameters have a significant influence on the fracture-etching profiles
obtained from the model. Beginning with this fracture-width distribution, we
have modeled the deformation of the fracture surfaces as closure stress is
applied to the fracture. The elastic properties of the rock, such as Young's
modulus and Poisson's ratio, have effects on the size of the spaces remaining
open after fracture closure. After the model yields the width profile under
closure stress, the overall conductivity of the fracture is then obtained by
numerically modeling the flow through this heterogeneous system.
In this paper, we introduce our models and investigate the effects of
permeability and mineralogy distributions and rock elastic properties on the
overall conductivity of an acid-etched fracture. A new acid-fracture
conductivity correlation is developed on the basis of many numerical
experiments.
© 2012. Society of Petroleum Engineers
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History
- Original manuscript received:
18 November 2010
- Meeting paper published:
24 January 2011
- Revised manuscript received:
26 August 2011
- Manuscript approved:
31 August 2011
- Published online:
16 February 2012
- Version of record:
1 May 2012
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