川西地区大邑构造煤系地层致密砂岩储层裂缝成因及意义

Genesis and significance of tight sandstone reservoir fractures in the coal bearing strata of the Dayi structure in western Sichuan region

裂缝是改善致密砂岩渗流能力并形成优质储层的关键因素。为明确川西地区大邑构造煤系地层中须家河组二段优质裂缝型储层分布规律,基于岩心观察、测井和地震等资料,开展了须二段深层致密砂岩储层裂缝发育特征研究。研究结果表明,大邑构造须二段储层主要发育断层伴生缝、褶皱伴生缝。其中断层伴生缝发育于断层附近,特别是断层末端、多条断层的交界部位为应力释放区,裂缝最为发育,延伸方向众多,在空间上构成裂缝网络系统,有利于储层的改造,是对油气运移、聚集最有效的裂缝,是大邑构造储层裂缝预测的主要目标。

Fractures are a key factor in improving the permeability of tight sandstone and forming high-quality reservoirs.In order to clarify the distribution pattern of high-quality fractured reservoirs in the second member of the Xujiahe Formation in the coal bearing strata of the Dayi structure in the western Sichuan region,based on core observation,logging,and seismic data,a study was conducted on the fracture development characteristics of the deep dense sandstone reservoirs in the second member of the Xujiahe Formation.The research results indicate that the reservoirs in the second section of the Xujiahe Formation in Dayi structure mainly develop fault associated fractures and fold associated fractures.Among them,the fractures associated with faults are developed near the fault,especially at the end of the fault and the junction of multiple faults as the stress release zone.The fractures are the most developed,with numerous extension directions,forming a fracture network system in space,which is conducive to reservoir transformation.They are the most effective fractures for oil and gas migration and accumulation,and are the main target for predicting reservoir fractures in the Dayi structure.