Experimental Study on Mud Intrusion in Tarim Tightly Fractured Reservoirs

In recent years, the problem of tight sandstone reservoir damage and protection has attracted the attention of scholars. Due to the existence of natural fracture channel communication, the fluids can easily enter the reservoir along the fractures during the development of fractured tight reservoirs and cause serious damage to the reservoir. In order to investigate the degree and mechanism of mud damage to fractured reservoirs, this paper conducts mud intrusion damage experiments with fractured tight sandstone reservoirs in Tarim Kucha Piedmont block as the research object. The experimental results show that the mud intrusion process can be divided into four stages according to the formation process of mud cake, namely, no mud cake stage, mud cake rapid generation stage, mud cake dynamic equilibrium stage and formation of sealing stage; the mud intrusion rate is affected by the reservoir permeability, mud cake permeability, fluid properties and specific gravity, and when the reservoir permeability is higher than the critical permeability, the intrusion rate is mainly determined by the filter cake permeability; by Scanning electron microscope results show that the blockage state of mud solid phase particles in core pore throat is divided into three kinds: blockage, adhesion and filling, and different blockage states have different degrees of damage to reservoir permeability. The mud dynamic damage analysis and solid-phase particle intrusion study obtained in this paper can help improve the complex reservoir simulator, which has certain guiding significance for the field construction operation and mud optimization.