鄂西渝东地区下三叠统飞仙关组鲕滩储层成岩作用及孔隙演化

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。

Diagenesis and Porosity Evolution Characteristics of Lower Triassic Feixianguan Formation in the Eastern Sichuan and Western Hubei

The lower Triassic Feixianguan Formation in the eastern Sichuan and western Hubei was composed of a set of carboncate rocks, and the reservoir was mainly developed in the oolite-shoal facies on the edge of carbonate platform. Based on the observation of petrology, combined with the chemical characteristics analysis of isotopes and microelement, we made a detailed research in the diagenesis of oolite-shoal. The mainly factors which control the production and development of the oolite-shoal include cementation, dolomitization and solution. Cementation can be found in every period of diagenesis progress, which primarily destroys the production of reservoir. Dolomitization can be orderly divided into blend water dolomitization and shallow burial dolomitization, to some extent it can be used to improve the formation of reservoir. Solution is composed of early freshwater solution and later deep burial solution. The deep burial solution is the key factor of production of reservoir. On the basis of these researches, we analyze and reach the results of the diagenetic environments, periods and the characteristics of porosity evolution, with which we can find the key factors of reservoir production.