基于格子玻尔兹曼方法的碳酸盐岩数字岩心渗流特征分析

Percolation properties analysis of carbonate digital core based on lattice Boltzmann method

基于不同分辨率的碳酸盐岩二维扫描电镜(SEM)图片,利用模拟退火法分别建立相应的大孔隙和微孔隙数字岩心,提出一种新的叠加耦合方法,构建能反映不同尺度孔隙特征的碳酸盐岩数字岩心,利用格子玻尔兹曼方法对数字岩心的渗流特征进行分析。结果表明:模拟退火法构建的数字岩心能够较好地表征真实孔隙之间的连通特性;叠加后的数字岩心能同时描述大孔隙和微孔隙特征,其渗透率(1.64×10-3μm2)均大于大孔隙数字岩心(1.12×10-3μm2)和微孔隙数字岩心(0.036×10-3μm2),微孔隙虽然本身渗透率很低,但对提高整个碳酸盐岩数字岩心的连通性有重要作用。

With two different resolution SEM images, 3D macro-pore and micro-pore digital cores were constructed respectively by the simulated annealing method. Then a superposition method was proposed to construct the carbonate digital core which could de-scribe different pore characteristics. Finally, lattice Bohzmann method was used to analyze the percolation properties. The results show that the simulated annealing method could reconstruct the 3D digital core with good connectivity. The superposition digital core could capture both the pore properties of macro-pore and micro-pore digital core, and the permeability of superposition digital core （1.64×10^-3μm^2） is even higher than the permeability sum of macro digital core （1.12×10^-3μm^2） and micro digital core （0.036×10^-3μm^2） , which show that the micro-pore has an important influence on connectivity in carbonate rocks.