川东北宣汉-达县地区构造演化及其对油气藏的改造作用

Tectonic Evolvement Function to Oil and Gas Pool's Reformation in Xuanhan-Daxian Area,Northeastern Sichuan Basin

川东北宣汉—达县地区是当前我国南方海相油气勘探的重要探区和突破区,在对该区约500 km2三维地震精细解释结果和区域构造背景综合分析的基础上,结合构造演化剖面和普光、毛坝场两个典型油气藏的综合特征,分析了不同时期、不同应力场下宣汉—达县地区构造样式及构造圈闭的形成与后期叠加改造。研究结果显示晚印支期普光、毛坝场等构造已具雏形,燕山晚期构造定型,在中构造层形成大量的北东向构造,喜山期被北西向构造叠加改造。进而从构造角度剖析了喜山运动特别是断裂、褶皱及局部构造的演化对早期油气藏的调整改造作用,研究表明喜山运动对宣汉—达县地区普光、毛坝场等构造圈闭油气藏的空间几何形态、构造演化特征、断裂疏导体系及储盖条件等均具有重要影响作用。

Xuanhan-Daxian area in northeastern Sichuan basin is one of the most important areas for the petroleum exploration in south China,it has been investigated for many years,and in 2003 it has been proved to be a new area which has plentiful petroleum resource by the well Puguang 1.Based on detailed interpretation of about 500 km^2 of three-demension seismic data and tectonic characteristics in northeastern Sichuan basin,according to the structure evolution profile and the similar features of two typical reservoirs of Puguang and Maobachang,the formation and stack of the structure styles in different stages and different stress fields have been studied, Puguang and Maobachang structural traps have their early prototype in later Indosinian Movement epoch,forming in later Yanshanian Movement epoch,being reconstructed in Himalayan Movement epoch.The reconstruction of Himalayan Movement to early carbonate rock reservoirs has been analyzed,especially the reforming function of the evolution of fault and fold system.The research shows that the Himalayan Movement has played a great important role in the structural geometry,tectonic evolution characteristics,fault system and reservoir-cap rock conditions of the carbonate rock reservoirs such as Puguang and Maobachang in Xuanhan-Daxian area.