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页岩中存在有机质孔隙和无机质孔隙,目前页岩气表观渗透率模型忽略了孔隙类型、孔隙半径分布对气体流动能力的影响.本文基于页岩二维剖光扫描电镜图像数值重建页岩三维数字岩心,并提取孔隙相中轴拓扑结构.根据地质上对有机质孔隙空间分布、有机质孔隙和无机质孔隙半径分布的认识,在对应孔隙喉道位置,充填满足对应孔隙半径分布以及空间分布关系的有机质孔隙和无机质孔隙,建立3种不同有机质孔隙分布模式的页岩孔隙网络模型:有机质孔隙条带状分布、有机质孔隙连片分布、有机质孔隙分散在无机质孔隙中.有机质孔隙中气体流动考虑吸附解吸、表面扩散、黏性流、努森扩散,无机质孔隙中气体流动考虑黏性流、努森扩散,气体性质计算考虑真实气体效应以及在微纳米孔道中相态变化.结果表明,当有机质孔隙半径分布小于无机质孔隙半径分布,有机质孔隙成条带状分布模型气体流动能力最强,有机质孔隙连片分布模型气体流动能力最弱.当有机质孔隙半径分布大于无机质孔隙半径分布,有机质孔隙成条带状分布模型气体流动能力最强,有机质孔隙分散在无机质孔隙模型气体流动能力最弱.本文的研究对认识页岩气流动能力具有显著意义.
In the shale, there are organic pores and inorganic pores. At present, the apparent permeability model of shale gas ignores the influence of pore type and pore radius distribution on the gas flow capacity. Based on the shale 2D shale scanning electron microscopy image reconstruction shale 3D digital cores and extract the central axis phase structure of pore facies.According to the geological understanding of pore space distribution of organic matter, the distribution of organic matter pores and inorganic pore radii, the corresponding pore radius distribution and spatial distribution Organic matter pores and inorganic pores, and established three different shale pore network models: pore distribution of organic matter, contiguous pore distribution of organic matter, and dispersion of organic matter in inorganic pores.The gas flow in the pores of organic matter Considering the adsorption and desorption, surface diffusion, viscous flow, Knudsen diffusion, gas flow in inorganic pores, viscous flow, Knudsen diffusion, the gas property calculation takes into account the real gas effect and the phase change in the micro / When the organic matter pore radius distribution is less than the inorganic pore radius distribution, there is The pore-stroma distribution model with the strongest pore structure exhibited the strongest gas flow and the weaker pore structure distribution in the organic matter.When the pore size distribution of organic matter was larger than that of inorganic pore, the gas flow capacity of the pore- Strong and organic pores have the weakest gas dispersion in the pores of inorganic pores.The research in this paper is of great significance for understanding the shale gas flow ability.