Pore Structure Evolution in Long-Term Water-Flooding Unconsolidated Sandstone Reservoirs

作者：Tao Yang, Hongming Tang, Yawei Hou, Yifan He, Bowei Liu, Peng Wang, Xiaoxu Peng, Min Zhang, Zhao Wang, Meng Wang · 发表于：Energy & Fuels · 年份：2025 · DOI：10.1021/acs.energyfuels.5c01372 · 被引用次数：8 · 研究领域：Hydrocarbon exploration and reservoir analysis、Hydraulic Fracturing and Reservoir Analysis、Enhanced Oil Recovery Techniques

Unconsolidated sandstones are characterized by low degrees of cementation, and the pore structure changes significantly during water injection development, which leads to a rapid increase in water content and an uneven distribution of the remaining oil. It is crucial to quantify the pore structure changes for water control and oil stabilization in unconsolidated reservoirs. Taking the PL A Oilfield as an example, this study clarifies the change patterns and mechanisms of pore structure in different types of reservoirs as affected by water flooding. The analysis combines core test data before and after flooding, quantitative analysis of full-scale casting thin sections, and nuclear magnetic resonance water-flooding experiments on sand-filled samples. The results indicate that significant changes occur in the pore structures of various reservoirs after long-term waterflooding. Specifically, the intergranular particle content and pore structure heterogeneity decrease, while the maximum and average pore throat radius increase. The proportion of large pores increases, while that of small pores decreases. Overall, these changes lead to an improved reservoir pore structure. The range of change decreases progressively from Class I to Class III, indicating that water flooding affects different types of reservoirs with varying intensity. Particle dispersion and migration during water flooding are the primary causes of changes in the pore structure. The main components of the particles ...