Study on the adaptability and optimized development model of water injection and huff-and-puff in tight oil reservoirs based on wettability characteristics: A case study of the Machong reservoir in the Santanghu Basin

After horizontal well development in the Machong tight oil reservoir of the Santanghu Basin, problems such as rapid reservoir pressure decline, significant productivity reduction, and low primary recovery efficiency have become prominent, highlighting the urgent need to establish an enhanced oil recovery technology system adapted to reservoir characteristics for efficient and sustainable development. Focusing on the wettability characteristics of the reservoir, this study systematically investigates the adaptability and optimization model of water injection and huff-and-puff technology. Comprehensive core experiments and wettability tests reveal that the reservoir rock surface exhibits predominantly weakly to strongly hydrophilic properties. Combined with evaluations of reservoir physical properties and oil-bearing characteristics, the study provides a theoretical basis for the application of water injection and huff-and-puff technology. Field pilot tests were conducted in multiple horizontal wells, and dynamic production data and pressure responses were analyzed comprehensively. The results show that the technology effectively mitigates production decline, significantly enhances daily oil output and cumulative recovery, and demonstrates high feasibility and efficiency in weakly hydrophilic tight reservoirs. Further analysis identifies injection intensity, injection pressure exceeding formation fracture pressure, and horizontal well trajectory position as key factors controlling huff-and-puff performance. Accordingly, an optimized injection–production parameter system matching the reservoir’s wettability characteristics was established. The findings indicate that a high-pressure injection–centered optimization model can substantially improve the development performance of tight oil reservoirs, providing a technical pathway and engineering reference for efficient injection–production in reservoirs with similar geological conditions.