页岩有机质存在大量的微纳米孔隙,分布在该尺度孔隙中的页岩气在开采条件下的流动表现为特殊复杂的流动形态,达西渗流定律已不适用于页岩储层微纳米尺度孔隙中气体流动的模拟计算与表征.采用格子Boltzmann方法,基于页岩气微观尺度气体流动特征,结合真实气体状态方程,建立了页岩微尺度气体流动的物理模型和数学模型,得到不同参数下微观气体边界滑移速度分布和压力分布规律.计算结果表明:孔隙尺寸和压力是页岩气在微纳米孔隙中的流动能力的决定性参数,孔隙尺寸和压力的增加将导致气体压缩效应增强,滑脱效应减弱;温度升高和压力降低均能促进吸附气体发生解吸,且页岩气的解吸吸附效应对于温度的变化相对于压力更敏感.该研究对认识页岩气微观流动规律具有重要的理论价值,对制订合理的开采制度,实现页岩气长效生产具有重要指导意义.%There are a great number of micro/nano pores in the organic matters of shale.When the shale gas in micro/nano pores is produced, its flowing patterns are special and complicated, so Darcy flow law is not suitable for the simulative calculation and characterization of gas flowing in micro/nano pores of shale reservoirs.In this paper, the characteristics of microscopic gas flowing in shale were analyzed.Then, its physical model and mathematical model were accordingly developed by using the lattice Boltzmann method (LBM) combined with the real gas state equation.And finally, the distribution laws of boundary sliding velocity and pressure of microscopic gas corresponding to different parameters were figured out.It is shown that pore size and pressure dominate the flowing capacity of shale gas in micro/nano pores.With the increasing of pore size and pressure, the compressibility effect of gas gets stronger and the slippage effect gets weaker.The increasing of temperature and the decreasing of pressure can both promote the desorption of adsorbed gas, and the desorption effect of shale gas is more sensitive to temperature change than to pressure change.The research results are theoretically valuable for understanding the microscopic flowing laws of shale gas.And they can play a guiding role in preparing rational development systems and realizing long-term efficient production of shale gas.
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