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鄂西渝东地区下三叠统飞仙关组主要为一套海相碳酸盐岩沉积,其储层主要分布在台地边缘鲕滩相带沉积中。以岩石学观察为基础,结合碳、氧同位素及微量地球化学特征分析对鲕滩储层成岩作用进行了详细的分析,研究表明该区鲕滩储层形成发育主要受胶结作用、白云岩化和溶蚀作用控制,其中胶结作用发生在成岩期后各个阶段,对储层形成主要起破坏性作用;白云岩化作用可分为混合水和浅埋藏白云岩化作用两期,对储层的形成起一定的改善作用;溶蚀作用分早期淡水和埋藏溶蚀作用两期,埋藏溶蚀作用对储层的形成起关键控制作用。在此基础上对该区储层形成的成岩环境、成岩序列及孔隙演化特征进行了分析总结,指出了有利储层形成的关键因素。
The Lower Triassic Feixianguan Formation in western Hubei and eastern Chongqing is mainly composed of marine carbonate deposits. The reservoirs are mainly distributed in the oolitic facies sediments on the margin of the platform. Based on the petrologic observations, the diagenesis of oolitic beach reservoirs is analyzed in detail based on the analysis of carbon and oxygen isotopes and trace geochemical characteristics. The results show that the formation and development of oolitic beach reservoirs in this area are mainly affected by cementation, dolomitization and Dissolution and cementation. The cementation takes place in all stages after diagenesis and plays a major destructive role in reservoir formation. Dolomitization can be divided into two phases: mixed water and shallow burial dolomitization, The improvement of dissolution is divided into two stages: early fresh water and burial dissolution, and burial dissolution plays a key role in the formation of the reservoir. On this basis, the diagenetic environment, diagenetic sequences and pore evolution characteristics of reservoirs formed in this area are analyzed and summarized, and the key factors for the formation of favorable reservoirs are pointed out.