复杂多孔介质多重介质模型的表征单元体

裂缝性岩体及缝洞型碳酸盐岩储层属于复杂多孔介质,岩体内部空隙为从纳米或微米级的微孔隙到数十厘米以上的大裂缝和溶蚀孔洞,空隙尺度跨越的范围很大。对于很多实际问题,由于单重介质模型计算不准确,且又不可能对复杂空隙空间结构在微观水平上进行精确描述,因此只能应用多重连续介质方法研究复杂多孔介质中的输运问题。该文给出了多重介质模型表征单元体的定义。在所研究问题的尺度范围内,这一多重介质模型表征单元体存在,复杂多孔介质的多重连续介质理论才能够成立。还以孔隙度和渗透率作为相关状态变量进行分析,研究了单重介质模型表征单元体和多重介质模型表征单元体间的联系,给出了复杂多孔介质多重介质模型的建立方法。

REPRESENTATIVE ELEMENTARY VOLUME OF THE MULTIPLE-CONTINUUM MODEL FOR COMPLEX POROUS MEDIA

Fractured rocks and naturally fractured vuggy Carbonate reservoirs are classified as complex porous media, characterized by complex pore systems, the size of which can range from nanometers or micrometers of micropores to tens of centimeters for large fractures and solution vugs. Due to the poor approximation in single-continuum model and the inability to describe the complex geometry of the surface bounding the void spaces at the microscopic level, multiple-continuum approach has to be adopted for transport phenomena analysis for most practical problems. The concept of representative elementary volume for multiple-continuum model is quantified. Multiple-continuum approach can be adopted for the complex porous media only if a representative elementary volume of multiple-continuum model can be defined in the field-scale domain. Porosity and permeability are selected as relevant state variables for the demonstration. The relationship between the representative elementary volume of multiple-continuum model and that of single-continuum model is investigated. A method to estibilish multiple-continuum model for the complex porous media is also presented.