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尽管经典渗流力学提出了达西定律存在适用的速度下限,但是没有明确低速状态下非达西渗流规律。选取了四川盆地须家河组7组致密砂岩气样品进行渗流物理模拟实验,每个样品测定10~15个渗流数据点,最高注气压力为10MPa,并始终保持环压高于注入压力2~3MPa,以确保气体是沿致密砂岩孔隙流动而不会沿着岩心与加持器内壁发生串流。实验模拟了气体在致密砂岩中的完整运移过程,有效探索了致密气渗流机制,提出致密砂岩气渗流具备极低速非线性渗流、低速非线性渗流和低速线性渗流3个阶段,以及具备复合型、下凹型、上凸型和直线型4种渗流曲线模式的新认识。
Although classical percolation mechanics proposed that Darcy’s law has a lower applicable speed limit, there is no definite non-Darcy flow law at low speed. Tight sandstone gas samples of 7 sets of Xujiahe Formation in Sichuan Basin were selected to conduct physical simulation experiments of percolation. 10 ~ 15 percolation data points were measured for each sample, the maximum gas injection pressure was 10MPa and the ring pressure was maintained at a pressure higher than 2 ~ 3MPa, to ensure that the gas flows along the pores of tight sandstone without flowing through the core and the inner wall of the holder. The gas migration process in tight sandstone has been experimentally simulated, and the mechanism of tight gas seepage has been explored effectively. Three stages of tight sandstone gas seepage with extremely low velocity non-linear seepage, low velocity non-linear seepage and low velocity linear seepage have been proposed, , Concave, convex and linear four kinds of seepage curve patterns of new understanding.