Microscopic Distribution Characteristics of Movable Fluid and Formation Mechanism in Fuyu Tight Reservoir in S Basin

Tight sandstone reservoir has the characteristics of strong heterogeneity, complex and diverse pore structure and obvious differentiation of seepage capacity. In order to clarify the seepage characteristics of tight reservoir, identify the distribution of movable fluid in tight reservoir, and explore the cause mechanism of the seepage capacity of tight reservoir. Therefore, this study takes the F reservoir of S Basin as the object, takes different oil content as the basis, and uses the centrifuge nuclear magnetic combined experiment to characterize the distribution of movable fluid, and analyzes the influencing factors of the distribution of movable fluid. The results show that: The pore structure characteristics of oil-immersed samples are good, the pore size is large, and the connectivity is strong. The movable fluid is mainly distributed in the middle pore and the large pore; The pore structure of fluorescence samples is complex, the pore development is poor, the pore size is mainly small hole and nano hole, the connectivity is poor, and the movable fluid is less. The oil spot samples were in between, with poor pore size distribution, poor connectivity and low mobile fluid saturation. By analyzing the distribution difference of movable fluid with different oil content, it is determined that the seepage capacity of tight reservoir is caused by the blocking of pore throat by clay minerals and the destruction of connected pores by carbonate cements. The results have important guiding significance for understanding the seepage characteristics and law of tight reservoir.