A pore space model for rock permeability and bulk modulus
作者:
Donald A. Seeburger,
Amos Nur,
期刊:
Journal of Geophysical Research: Solid Earth
(WILEY Available online 1984)
卷期:
Volume 89,
issue B1
页码: 527-536
ISSN:0148-0227
年代: 1984
DOI:10.1029/JB089iB01p00527
数据来源: WILEY
摘要:
A simple network model of pore space in rocks has been developed with which permeability and bulk modulus as a function of confining pressure can be calculated. Pores are modeled as straight conduits with circular, elliptic, or tapered cross sections. The interconnection of these conduits is modeled by emplacing them in regular two‐dimensional hexagonal, square, or triangular networks. Flow through each conduit is modeled using Poiseuille's law. Flow through the network is calculated based upon the analogy of fluid flow in Darcy's law to current flow in Ohm's law. An estimate of the effective bulk modulus is obtained by summing the contributions of the individual pores. The effect of confining pressure on permeability and bulk modulus is determined by the solid properties and the shape of the pores. For appropriate aspect ratio distributions, the permeability and bulk modulus characteristics of the network model are similar to those found for laboratory rock samples. For rocks of moderate porosity, like sandstone, the model predicts that the bulk modulus is most affected by small, low aspect ratio pores. In contrast, for rocks like granite and tight sandstones (permeability less than 0.5 mdarcy) in which there are relatively few round pores, the bulk modulus and the permeability are both controlled by easily deformed pores. These types of responses are observed in experimental data. The success of the model in predicting these general bulk modulus and permeability responses indicates that while the models presented are too simple to represent a rock completely, the network theory approach is a promising method for modeling porous medi
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