Influencing Factors of Reservoir Quality and Movable Fluid Characteristics: A Case Study for Tight Sandstones of Shanxi Formation to He8 Member in Southwestern Ordos Basin, China

Typical tight sandstone reservoirs are present in the Shanxi Formation to He8 Member (P 2 s‐P 2 h 8 ), in the southwestern Ordos Basin. However, reservoir characterisation in this area remains insufficient. The effects of provenance, deposition and diagenesis on reservoir quality and movable fluid saturation have received limited attention and the diagenetic evolution characteristics of different reservoir types remain poorly understood. This study improves the characterisation of tight sandstone reservoir quality through the integrated application of petrographic observations, petrophysical measurements, pore‐structure analyses and movable fluid saturation. Compared with conventional approaches, quality characteristics of reservoir are more accurately characterised, especially the contribution of fractures to reservoir flow capacity. The tight sandstones are predominantly litharenite and sublitharenite. Dissolution‐generated secondary pores and fractures significantly enhance reservoir quality. Compaction and cementation are the primary causes of pore destruction, and the effect of compaction on pore destruction is stronger than that of cementation. Movable porosity shows a stronger correlation with permeability ( R 2 = 0.7502) than total porosity ( R 2 = 0.6151). The quality of P 2 s‐P 2 h 8 tight sandstone reservoirs is significantly influenced by provenance and depositional processes. Provenance‐controlled parameters include quartz content, lithic fragment content and volcanic lithic fragment content. Grain size and sorting are controlled by deposition. These parameters influence the pathways and intensity of diagenetic processes. Distributary channel sandstones are characterised by coarser grain size, relatively better sorting, and lower lithic fragment contents. These attributes enhance their resistance to compaction, allowing a greater proportion of primary pores to be preserved. In addition, secondary dissolution is more extensively developed during diagenesis, resulting in superior reservoir quality. In contrast, mouth‐bar and beach‐bar sandstones exhibit poorer textural characteristics, weaker resistance to compaction, and substantial loss of primary porosity. The relatively limited intensity of dissolution further restricts pore development, ultimately leading to poorer reservoir quality. The western provenance exhibits slightly better reservoir quality than the northern provenance, whereas the southwestern provenance shows the poorest reservoir quality. These findings provide a novel framework for evaluating and predicting the quality of tight sandstone reservoirs in complex geological settings.