【摘要】 目前常用的数字岩心数值重构方法都是基于常压下得到的扫描电镜(SEM)图片或CT扫描结果,导致数字岩心孔隙结构与实际地层有偏差,不利于分析页岩的孔隙特点及模拟页岩气在数字岩心中的流动。本文基于二维数字岩心和岩石弹性力学方程建立了应力条件下页岩数字岩心矿物骨架和有机质的位移计算模型,对数字岩心孔隙结构进行了修正,得到了应力条件下的页岩数字岩心。利用模型模拟了不同应力条件下岩心的孔隙结构变化规律,结果表明:有机质中的纳米孔隙对应力更加敏感,随应力变化的程度更大。对于比较细长的孔隙,受到应力作用后沿短轴方向的位移要比沿长轴方向的要大,会导致一些细长孔隙闭合或形成几个孤立的孔隙。孔隙压力对有机质纳米孔影响最大,会影响页岩气在有机质纳米孔中的流动。数字岩心的修正为进一步利用格子Boltzmann方法研究页岩气的微观渗流规律提供了更准确的流动通道模型。更多还原

【Abstract】 At present, the commonly used numerical reconstruction methods for digital cores are based on the scanning electron microscopy(SEM) images or CT scanning results obtained at atmospheric pressure, which is unrepresentative of the condition of the formation. It is not conducive to analyzing the pore structure of shale and simulating the flow of shale gas in digital rocks. In this paper, a displacement calculation model of shale matrix mineral and organic components has been established based on two dimensional digital rock and rock elastic mechanic equations. The pore structure of the digital rock model was modified under confining stress and pore stress. The effect of stress on pore structure of shale has been studied using the displacement calculation model. The simulation results indicate that the nano pores in organic components are more sensitive to stress. For the slinpores, the displacement along the minor axis is bigger than that along the major axis under stress, which induces the long pores to close or to form some isolated pores. The pore pressure has more significant effect on nano pores, which will affect the shale gas flow in nano pores. The modification of digital core provides an accurate flow path for the future study on shale gas micro seepage flow using the lattice Boltzmann method.更多还原