四川盆地川东地区三叠系嘉陵江组第二段滩微相的发育分布及对气藏形成的控制

The Development and Distribtuion of the Triassic Bank-Microfacies in the 2-Section of Jialingjiang Group and Its Gas-Poal Control Nature in the Eastern Part of Sichuan Basin

四川盆地川东地区三叠系嘉陵江组第二段滩微相的发育，受海平面相对升降的控制。提出了浅海滩和变浅暴露滩的新分类，分析了滩微相的古地理和层位分布规律，建立了滩的组成模型，总结了滩发育的三种相序模式。变浅暴露滩有有利的生、储和盖组合，发育的孔隙层段，早期形成的沉积－成岩圈闭，控制了各种圈闭中裂缝－孔隙型气藏的形成。上述思想提供了与滩有关的气藏勘探的新思路。

The 2-section of Jialingjang Group of Triassic in the eastern part of Sichuan Basin is an important gas bearing position. The Development of bank-micro factes have played an important pole in controlling the gas pool of fracture-pore type in traps.The banks are POint-bank on the platform in upper yangtze epicontinental sea. The new classificantion of shallow-sea bank and shallow exposed banks has been suggested on the basis of the evolution model of depositional environments which were controlled by relative sea-level changes. The similarities and difference of two types of banks have been compared. There were four bank development periods in the multicycle sedements of 2-section of Jialingjiang Group.The distribution of banks in two bank-development periods, for example, the 2-subsection of 2-section, have been mapped. The composition and devolopment model of point-bank at the Tishan anticline has been analysed. It clearly points out that the lithic factes in the core of bank have big thickness and good continuity in the multi-bank development periods. There are three types of factes sequences models:(1) the banks developed with sea-level up and disappeared with sea-level down; (2) the banks developed with sea-level down and disappeared to expose ; and (3) the banks developed with sea-level up and disappeared with sea-level up.Finally, the authors state how the shallow exposed bank control the formation of gas-pool. It has been recognind: ①the bank-microfacies complexs are beneficial for complexs of oil-producing, reservoir and seal formations, ②the shallow exposed bank is the microfacies zone of the pore-layers devolopment, ③ the sediment-diagenetic trap formed in bank-microfacies zone is beneficial for early accumulation of oil and gas pools @the development of pore-layers and accumulation of oil and gas in early sediment-diagenetic traps are the base of present gas -pool of fracture-pore type in various traps.