【摘要】 为了从微观尺度上探讨低渗透气藏液相侵入微观流动机理,采用激光刻蚀技术建立了致密砂岩孔隙网络模型,开展了液相侵入微观可视化流动实验,分析了液相侵入和流体返排过程孔隙网络内水相的动态分布;建立了基于等效毛细管束的低渗透气藏液相侵入微观流动模型,采用致密砂岩水相自吸侵入实验验证了模型的可行性。实验发现,孔隙网络内水相侵入与毛细管力侵入规律类似,初期液相主要沿着较大孔隙流动,液相通过与孔隙连通的喉道逐渐推进;较小喉道中的水相难以返排,阻碍气相的流动。研究结果表明,黏滞阻力对致密砂岩水相侵入起主导作用,但在负压差条件下,液相仍能侵入岩心,且岩石越致密,水相最大侵入深度越大。建立的液相侵入模型为低渗透气藏液相侵入损害及保护机理研究提供了理论参考。更多还原

【Abstract】 The goal of this study was to avoid formation damage by finding a better way to map the flow of fluids through pore networks in tight sandstones. In order to investigate the flow mechanism of liquid phase invasion in low permeability gas reservoirs from the microscopic scale, a pore network model of tight sandstone was established by using laser etching technology. In that way, the microscopic visualization flow experiment of liquid phase invasion was carried out, and the dynamic aqueous phase distribution in the pore network during the process and fluid flow back was analyzed. The liquid phase invasion microscopic flow model for low permeability gas reservoirs was established based on equivalent capillary beam, and the model was verified by aqueous phase self-absorption invasion experiment in tight sandstone. Experimental results showed that the rule of aqueous phase invasion in the pore network is similar to that of capillary force invasion. The liquid phase mainly flows through larger pores initially, and then advances through the throats communicating with the pores gradually; It is difficult for the aqueous phase in the smaller throat to flow back,which can hinder the flow of gas phase. The research suggested that viscous drag plays a dominant role in the invasion of aqueous phase in tight sandstone; the liquid phase can still invade the core under negative pressure difference.Further, the denser the rock, the greater the maximum invasion depth of aqueous phase would be. The established liquid phase invasion model will provide a theoretical reference in studying liquid phase invasion damage and protection mechanism of low permeability gas reservoirs.更多还原