The relation between permeability and grain size distribution

Abstract

Interstitial fluid flow in reservoir rocks for oil, gas, and unconventional resources has a great influence to the production efficiency. In the present study, we simulate fluid flow in reservoir rocks and analyze the relationship between the permeability and the grain size distribution. We used a smoothed particle hydrodynamics (SPH) method, which is one of the particles methods, to simulate fluid flow in reservoir rocks. It is known that the grain size distribution of reservoir rocks obeys the Weibull distribution in many cases. The probability density function of the Weibull distribution is determined by the shape parameter and the mean value. We modeled plural three-dimensional digital specimens of poroelastic medium composed of matrix and pore space. The grain size distribution of the specimens has the Weibull distribution with different shape parameters. We estimated the permeability of each digital specimen using fluid flow simulations. The numerical results showed that the permeability of reservoir rocks is affected by the shape parameter and the mean value, i.e., two major parameter of the Weibull distribution. From this result, it is suggested that the permeability of reservoir rocks can be estimated from the shape parameter and the mean grain diameter of the grain size distribution, and the accuracy of the simulation of flow in reservoir rocks could be enhanced in the future.