四川盆地川中隆起安岳气田震旦系灯影组储层差异性成岩演化

Differential diagenetic evolution of Sinian Dengying Formation reservoirs in Anyue gas field, Central Sichuan Uplift, Sichuan Basin

杨程宇 于博 张剑锋 王铁冠 李美俊 倪智勇

YANG Chengyu YU Bo ZHANG Jianfeng WANG Tieguan LI Meijun NI Zhiyong

中国石油大学(北京) 克拉玛依校区 石油学院, 新疆 克拉玛依 834000 中国石油大学(北京) 油气资源与工程全国重点实验室, 北京 102249 国家管网集团 储能技术有限公司，上海 200011

Faculty of Petroleum, China University of Petroleum (Beijing) at Karamay, Karamay, Xinjiang 834000, China State Key Laboratory of Petroleum Resources and Engineering, China University of Petroleum (Beijing), Beijing 102249, China PipeChina Energy Storage Technology Co., Ltd., Shanghai 200011, China

四川盆地川中隆起震旦系灯影组白云岩中发育大型原位裂解气藏，研究其沉积和成岩作用对储层的影响可为古老的深层碳酸盐岩储层评价与预测提供重要依据。通过岩心样品的手标本观察、薄片鉴定、阴极发光以及扫描电镜分析，系统研究了灯影组四段白云岩储层的岩性差异、成岩作用类型、成岩序列以及不同岩性对成岩作用过程的约束作用。川中隆起灯影组储层主要岩性为具骨架—填充结构的藻叠层云岩、颗粒云岩和以细粒白云石堆积为主的泥—粉晶云岩；主要的成岩作用类型依次为压实作用、同生—准同生期以及表生期的溶蚀和胶结作用、埋藏期的亮晶胶结作用以及晚期热液作用，油气的充注时间晚于亮晶胶结作用，而油气的裂解与热液作用时期相近。灯影组四段白云岩储层为典型的T型碳酸盐工厂形成的台地藻丘体建造沉积，其中藻叠层云岩和颗粒云岩受到的压实作用较弱，但同生—准同生期以及表生期胶结与溶蚀作用较强。亮晶胶结作用造成孔隙大幅减少，残余粒间孔得以保存至油气充注期，随着晚期热液的侵入，热液矿物和裂解形成的焦沥青又进一步充填了孔隙。泥—粉晶云岩遭受了较强的压实作用，同生—准同生期以及表生期胶结作用较弱，亮晶胶结进一步减少了孔隙，残余孔隙同样保留至液态烃充注，泥—粉晶白云岩中未见明显的热液侵入痕迹，但热液传递的高温仍促使液态烃裂解进而形成了焦沥青。

Large in-situ pyrolysis gas reservoirs have developed in the dolomites of the Sinian Dengying Formation in the Central Sichuan Uplift, Sichuan Basin. Investigating the effects of sedimentation and diagenesis on these reservoirs provides important insights for evaluating and predicting ancient deep carbonate reservoirs. Through hand specimen observation, thin-section identification, cathodoluminescence, and scanning electron microscopy (SEM) of core samples, the study systematically analyzed the lithological variations, diagenetic types, diagenetic sequences, and the constraints imposed by different lithologies on diagenetic processes in the dolomite reservoirs of the fourth member of the Dengying Formation. The results showed that the main lithologies of the Dengying Formation reservoirs in the Central Sichuan Uplift were algal stromatolite dolomite with a skeleton-filling structure, granular dolomite, and mud-fine crystalline dolomite mainly composed of fine-grained dolomite accumulations. The main types of diagenesis followed the sequence of compaction, dissolution, and cementation during the syngenetic-penecontemporaneous and supergene stages, sparry cementation at the burial stage, and late-stage hydrothermal activity. Hydrocarbon charging occurred after sparry cementation, while hydrocarbon pyrolysis coincided with hydrothermal activity. The dolomite reservoirs in the fourth member of the Dengying Formation were algal mound platform deposits formed by typical T-type carbonate factories. The algal stromatolite dolomite and granular dolomite experienced weak compaction but stronger cementation and dissolution during the syngenetic-penecontemporaneous and supergene stages. Sparry cementation significantly reduced porosity, and residual intergranular pores were preserved until the hydrocarbon charging period. With the intrusion of late-stage hydrothermal fluids, these pores were further filled with hydrothermal minerals and pyrobitumen formed through pyrolysis. In contrast, the mud-fine crystalline dolomite underwent strong compaction and weaker cementation during the syngenetic-penecontemporaneous and supergene stages. Sparry cementation further reduced porosity, and residual pores were also preserved until liquid hydrocarbon charging. No obvious signs of hydrothermal intrusion were observed in mud-fine crystalline dolomite, but the high temperature of hydrothermal fluids still promoted liquid hydrocarbon pyrolysis, leading to pyrobitumen formation.

中央高校基本科研业务费专项资金“储层焦沥青的形成机理及地质意义研究” 2462023YJRC011;国家自然科学基金青年基金项目“储层焦沥青的过成熟有机质热演化标尺及构造—热事件表征” 41903059

https://doi.org/10.11781/sysydz2025040754