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基岩孔隙是页岩气藏的主要储集空间.页岩有机质孔隙和非有机孔隙具有不同的赋存方式和传输机制:有机质孔隙存在吸附气、游离气两种赋存方式,无机质内仅存在游离气,气体在有机质孔隙存在吸附解吸和吸附气的表面扩散.传统的数值模拟方法未考虑页岩基岩内不同孔隙介质储集方式和运移机制的差异性,未考虑有机质分布结构特征的影响.本文基于均匀化理论建立了考虑页岩基岩有机质分布特征和相应运移机制的尺度升级数学模型,在小尺度模型中考虑有机质和无机质赋存方式和运移机制的差异性.数值模拟结果表明,传统上具有相同宏观运移参数的基岩,若其有机质分布不同,采用尺度升级后的宏观模型计算的压力变化和产量均不同,必须进行尺度升级才能实现复杂结构分布的页岩基岩模拟的准确性.
The bedrock porosity is the main reservoir space of shale gas reservoirs.Shale organic pores and non-organic pores have different modes of occurrence and transport mechanism: there are adsorption gas and free gas in organic matter pores, There exists free gas, the gas is adsorbed and desorbed on the pores of organic matter, and the surface of adsorbed gas diffuses.The traditional numerical simulation method does not consider the difference of reservoir and transport mechanism of different pore media in shale bedrock without considering the distribution characteristics of organic matter Based on the theory of homogenization, a scale-up mathematical model considering the distribution characteristics of organic matters and the corresponding migration mechanism of shale bedrock is established in this paper, and the difference of organic matter and inorganic matrix and transport mechanism is considered in the small-scale model. The simulation results show that the bedrock which traditionally has the same macroscopic transport parameters, if the distribution of organic matter is different, the pressure change and yield calculated by the macroscopic model after scale upgrade are different, and the scale structure must be upgraded to realize the shale with complicated structure distribution Accuracy of bedrock simulation.