【摘要】 四川盆地东北部在早三叠世飞仙关期的大部分时间内(飞一—飞三期)属于四周被深水海槽围绕的、受南秦岭海演化拉张断裂而形成的一个碳酸盐孤立台地环境,随四级海平面的升降变化、开江—梁平海槽的逐渐关闭和城口—鄂西海槽的东移,各种孤立台地亚相发生移动和转变,最终在飞三晚期至飞四早期孤立台地转化合并为川东北大型连陆台地。根据区域地质背景和地层沉积特征(岩性、古生物、沉积构造、测井)研究,划分了潟湖(包括蒸发潟湖、局限潟湖、半局限潟湖和点滩)、台地边缘鲕滩、斜坡、海槽4个亚相;建立出孤立台地的沉积立体模式并分析了沉积相从飞一飞三期的展布及演化过程;最后着重剖析了具备后期形成良好储层条件的孤立台地边缘鲕滩相带的迁移性、储层发育不均一性、测井和地震特征,沉积相对鲕滩气藏分布的控制,最后对孤立台地边缘鲕滩相中有望成为新的天然气勘探突破区进行了地震横向分布预测。更多还原

【Abstract】 In most times of the Early Triassic Feixianguanian age (from phases 1 to 3), the northeastern Sichuan basin was in an environment of isolated carbonate platforms surrounded by a deep sea trough and formed by extensional faulting during the evolution of the South Qinling Mountain ocean. Concomitantly with the sea-level change, gradual closing of the Kaijiang-Liangping sea trough and eastward migration of the Chenkou-Exi sea trough, various isolated carbonate platform subfacies moved and were transformed, and finally the isolated carbonate platforms were transformed and amalgamated into a unifying large-scale land platform in northeastern Sichuan from the late part of the third phase to the early part of the fourth phase of the Feixianguanan age. On the basis of the regional geological setting and sedimentary characteristics (lithology character, paleontology, sedimentary structure and logging), the lagoon (including evaporative lagoon, restricted lagoon, semi-restricted lagoon and point beaches), platform-margin oolitic beach, slope and sea trough subfacies. A stereoscopic depositional model of isolated platforms was constructed and the distribution and evolutionary process of sedimentary facies from phases 1 to 3 of the Feixianguanan age were analyzed. Finally the authors analyzed the migration of the platform-margin oolitic beach facies belt that had conditions for the formation of good reservoirs in the late stage, inhomogeneity and log and seismic characteristics of the reservoirs and control of sedimentary facies on the distribution of oolitic beach gas reservoirs and made seismic lateral distribution forecast for the areas in platform-margin oolitic beach facies which are expected to become new breakthrough areas of gas exploration.更多还原