Abstract
The water blocking damage to the reservoir caused by the invasion of external fluid is one of the main factors that affect the efficient development of tight sandstone gas reservoirs. In this paper, microfluidic chip technology is used to explore the causes of water blocking damage in porous media and find suitable recovery solutions. The research results show that reducing the gas-liquid capillary pressure can effectively reduce the rate and quantity of spontaneous speed of cores. After chemical treatment, the liquid phase fluidity of the non-fractured matrix core is increased by 1.72 times, and that of the fractured core is increased by 2.13 times. In water wetting porous media, there are mainly four types of liquid hold-up: (1) Liquid hold-up in the dead volume of a non-connected pore; (2) The water phase in the pore throat with a small inner diameter cannot be driven away due to its larger capillary pressure; (3) Adsorption viscous force, the wetting phase is adsorbed on the surface of the solid phase; (4) Reservoir heterogeneity. The water blocking damage can be removed to a certain extent by changing the gas injection pressure, the gas injection method, or adding a wetting modifier.