Genesis and Evolutionary Process of Overpressure in the Wufeng-Longmaxi Formations, Luzhou Area, Sichuan Basin

四川盆地泸州地区作为川南页岩气勘探开发主力区块，五峰组–龙马溪组页岩气藏普遍发育强超压，且超压特征与页岩气高产密切相关。前人研究多聚焦于超压主控因素定性分析，但对该区多因素复合增压机制及定量贡献缺乏系统研究。文章通过多方法结合，揭示泸州地区超压成因机制及演化规律，为页岩气成藏与保存评价提供科学依据。通过测井曲线组合、Bowers图版识别泸州地区为复合型成因超压；对裂缝脉体开展薄片观察、阴极发光、显微测温及激光拉曼光谱测试，恢复甲烷包裹体捕获压力为82.76~108.99 MPa；结合所收集的三轴主应力数据，利用构造挤压增压模型，计算构造挤压增压贡献量为4.3~11.5 MPa；基于钻井基本数据及有机质成熟度等关键边界参数，利用盆地数值模拟方法，恢复泸州地区五峰组–龙马溪组埋藏–热演化史与压力演化历史，综合分析认为泸州地区为“早期有限聚集–中晚期持续富集–晚期构造保存型”超压演化模式。The Luzhou area in the Sichuan Basin, as a key block for shale gas exploration and development in southern Sichuan, exhibits widespread strong overpressure in the Wufeng-Longmaxi shale gas reservoirs, with overpressure characteristics closely linked to high gas production. Previous studies primarily focused on qualitative analysis of overpressure controls, but systematic research on the multi-factor composite overpressure mechanisms and their quantitative contributions remains lacking. This study integrates multiple methods to unravel the genetic mechanisms and evolutionary patterns of overpressure in the Luzhou area, providing scientific insights for shale gas accumulation and preservation assessment. By combining well-log curves and Bowers plots, the overpressure in the Luzhou area was identified as having a composite origin. Thin-section observations, cathodoluminescence, microthermometry, and laser Raman spectroscopy of fracture veins revealed methane inclusion entrapment pressures of 82.76~108.99 MPa. Combined with triaxial principal stress data, tectonic compression overpressure contributions of 4.3~11.5 MPa were calculated using a tectonic compression overpressure model. Basin numerical modeling, constrained by drilling data and key boundary parameters (e.g., organic matter maturity), reconstructed the burial-thermal evolution history and pressure evolution history of the Wufeng-Longmaxi Formation. Comprehensive analysis suggests an overpressure evolution model characterized by “limited early accumulation, sustained mid-late enrichment, and late-stage tectonic preservation” in the Luzhou area.