基于均匀化理论的页岩基质流固耦合尺度升级

页岩基质通常由微尺度的有机质和无机质组成,由于这两种介质的力学性质差异较大,且气体在两者中的赋存方式和流动机制均不相同,要准确刻画气体在页岩基质中的流固耦合过程,需针对两种介质建立不同的微尺度模型,但由于计算效率问题,微尺度模型无法直接用于宏观模拟.基于均匀化理论建立一种页岩基质流固耦合尺度升级方法,将微尺度上有机质和...

Upscaling of hydro-mechanical coupling in shale matrix based on homogenization theory

In shale gas reservoirs,gas is mainly stored in shale matrix.Therefore,to establish a hydro-mechanical coupling(HM)model in shale is important for the macroscopic HM simulation of shale gas production.At microscopic scale,shale matrix is usually composed of organic and inorganic matters.The mechanical properties of these two media are quite different,and so that both gas storage type and transport mechanisms are different in the two media.Thus it is necessary to develop different microscale models to accurately describe the HM process of gas in shale matrix.However,the microscale models cannot be straightly applied to macroscale simulation due to huge calculation time and data storage requirement.In this study,an efficient upscaling method based on the homogenization theory was proposed for the HM process in shale matrix,which can accurately represent the microscale characteristics of the organic and inorganic matters in macroscale simulations.Firstly,the shale matrix is assumed as a heterogeneous porous elastic medium composed of organic and inorganic matters,and the microscale HM models were developed according to different storage type and transport mechanism of real gas in these two media.Then,the microscale HM models were homogenized to obtain the equivalent macroscopic HM models for the shale matrix,along with the definition and calculation method of equivalent parameters in the micro and macro models.Lastly,the accuracy and application of the proposed method were verified via several case studies,and the influence of the mechanical properties,the content and distribution of organic matters on the macro HM simulation in shale gas production were also analyzed.The results indicate that the cumulative gas production increases with the decrease of the elastic modulus of the organic matter,and it correlates positively with the connectivity of the inorganic matter.Besides,at early period,gas production decreases with the increase of the total organic content,but it will increase at late period of the process.