岩石物理的理论模拟和数值实验新方法

A new method for theoretical modeling and numerical experiments on petrophysical studies

当代物理实验科学和计算机科学技术的巨大进步为岩石物理的理论和实验研究开辟了新的领域.在细胞自动机基础上发展起来的格子气自动机和格子玻尔滋曼方法就是这种技术进步的产物.本文讨论了格子气自动机的发展及其应用于研究多孔岩石微观孔隙结构对宏观导电特性影响的新方法. 我们开发的模拟多孔岩石导电特性的数值实验新方法,提供了一种可深入到从微观孔隙结构这个尺度上来考察具有复杂孔隙结构的,孔隙度小于10%的低孔、低渗岩石的宏观导电特性及其影响因素.研究表明:Archie 系数m,n并不是传统上的意义,研究各种不同条件下F-、I-Sw 关系,结果显示非阿尔奇现象与孔隙介质中孔隙、骨架和流体的混合导电网络有关,得出新的饱和度计算公式.同时还研究了泥质含量和分布、电阻率各向异性对宏观导电特性的影响,提出适用于电阻率各向异性地层的F-、I-Sw 的关系.本文最后探讨了应用格子气自动机和格子玻尔滋曼方法进行岩心渗流和核磁共振数值实验的新方法及其发展前景.

The rapid development of modern physical sciences and computer technology opened new prospects for petrophysical studies Now, the Lattice Gas Automation (LGA) and Lattice Boltzmann (LB) are such powerful tools to study the micro dynamics of fluid flow and electrical current in a complex media. It can provide insight into the mechanisms of the micro phenomenon. In this study, we studied electrical transport properties of porous media with 2D LGA. Contrary to the traditional viewpoints,our simulating results clearly disclosed the physical meaning of the Archie parameters a, b, m, n. The simulation results also demonstrate that the so called non-Archie behavior of the porous rocks is the inherent nature of the complex current paths of the rock matrix and pore fluids mixture. It is proved by our results that Archie equations are merely the linearized approximations of F- and I-S w relations of porous media in the moderate ranges of porosity and fluid saturation. We thus developed a set of new equations to calculate fluid saturation with electrical measurements. The new equations can be applied to much broader ranges of porosity and fluid saturation with higher accuracy. Investigations on electrically anisotropic porous media are also carried out to simulate the F- and I-S w relations along different directions. We found it would result in erroneous for electrically anisotropic rocks if we apply the F- and I-S w relations obtained by the measurements along one direction. A new formula was developed to combine the measurements in all directions to calculate fluid saturation in anisotropic media. We finally discussed in this paper the prospects of applying LGA and LB to simulate acoustic and nuclear magnetic resonance fields to determine the production parameters of complex reservoirs.