四川盆地中部天府气区侏罗系沙溪庙组致密砂岩气储层岩石相类型与演化特征

Petrofacies types and evolution characteristics of tight sandstone gas reservoirs of Jurassic Shaximiao Formation, Tianfu gas area, central Sichuan Basin

关旭 庞小婷 冉崎 杨长城 王小娟 朱德宇 潘珂 李飞 肖柏夷 曹斌风

GUAN Xu PANG Xiaoting RAN Qi YANG Changcheng WANG Xiaojuan ZHU Deyu PAN Ke LI Fei XIAO Boyi CAO Binfeng

中国石油 西南油气田公司 勘探开发研究院, 成都 610041 中国石油 西南油气田公司, 成都 610051 西北大学 地质学系, 西安 710069

Exploration and Development Research Institute, PetroChina Southwest Oil & Gasfield Company, Chengdu, Sichuan 610041, China PetroChina Southwest Oil & Gasfield Company, Chengdu, Sichuan 610051, China Department of Geology, Northwest University, Xi'an, Shaanxi 710069, China

岩石类型划分对表征致密砂岩储层非均质性和揭示其差异演化过程具有重要意义。以四川盆地中部天府气区中侏罗统沙溪庙组为研究对象，利用岩石薄片、扫描电子显微镜、稳定碳氧同位素等分析测试手段，研究储层岩石相类型及成岩演化过程。天府气区沙溪庙组含气储层在物性、孔隙类型和分布上表现出强非均质性。基于岩石学组分和结构、成岩方式和过程及孔隙结构特征的差异，划分了4种类型的岩石相，包括贫塑性颗粒砂岩、富塑性颗粒砂岩、方解石致密胶结砂岩和浊沸石致密胶结砂岩。在储层演化过程中，贫塑性颗粒砂岩经历了中等压实作用，流体—岩石反应活跃，溶蚀作用强烈，普遍经历了多期溶蚀和胶结作用，是有效的储集岩石相；富塑性颗粒砂岩机械压实强烈，在成岩早期已变得致密，晚期流体活动弱，溶解微弱；方解石致密胶结砂岩和浊沸石致密胶结砂岩中方解石和浊沸石连晶式胶结，早期胶结致密化，晚期流体改造也较弱。沉积物原始组分和结构控制了储层中成岩作用方式和程度的差异。利用岩石相的概念可系统识别影响储层孔隙度和渗透率的关键岩石学参数，将其与测井信息相结合，可有效指导储层属性建模。

The classification of rock types is important for characterizing the heterogeneity of tight sandstone reservoirs and revealing their differential evolution process. The Middle Jurassic Shaximiao Formation in the Tianfu gas area of the central Sichuan Basin was selected as the study object, and petrofacies types and diagenetic evolution process were investigated using thin-section observation, scanning electron microscopy (SEM), and stable carbon and oxygen isotope analysis. The gas-bearing reservoirs of the Shaximiao Formation in the Tianfu gas area exhibit strong heterogeneity in physical properties, pore types and distribution. Based on the differences in petrographic composition and texture, diagenetic patterns and processes, and pore structure characteristics, four types of petrofacies were classified: ductile-lean sandstone, ductile-rich sandstone, tightly calcite-cemented sandstone, and tightly laumontite-cemented sandstone. During the reservoir evolution process, ductile-lean sandstone experienced moderate compaction, active fluid-rock interactions, and strong dissolution, and generally underwent multiple stages of dissolution and cementation, resulting in effective reservoir petrofacies. Ductile-rich sandstone underwent strong mechanical compaction, became dense in the early diagenetic stage, and exhibited weak fluid activity and slight dissolution in the late stage. In tightly calcite- and laumontite-cemented sandstone, calcite and laumontite were interlocked, resulting in early-stage densification and late-stage weak fluid modification. The original composition and texture of sediments controlled the differences in the influencing patterns and degrees of diagenesis within reservoirs. The concept of petrofacies provides a systematic framework for identifying key petrographic parameters that influence reservoir porosity and permeability. In combination with well logging data, this approach can effectively guide reservoir property modeling.

中国石油西南油气田公司重大科技专项“四川盆地中西部地区致密气勘探开发理论及关键技术研究” 2022ZD01

https://doi.org/10.11781/sysydz2025040767