海相碳酸盐岩层系不整合量化研究及其意义——以四川盆地北部二叠系为例

本文以四川盆地北部二叠系为例,将层序地层分析和沉积盆地波动过程分析相结合,提出了运用沉积波动过程分析研究沉积记录不完整性的量化方法,该方法可以相对准确地定量描述盆地形成演化过程中的升降运动,恢复无地层"记录"中的沉积-剥蚀过程,进而定量分析盆地的沉积-剥蚀过程、计算沉积间断(不整合)内的地层剥蚀量、认识其时空分布规律.同时,通过实际钻井及"人工井"的波动过程分析,结合地震剖面解释成果,可以作出主要不整合的空间分布图、各层位的剥蚀厚度图和原始厚度图、各期构造的剥蚀量分布图等重要基础图件,为盆地进一步系统分析及盆地模拟打好基础,结合沉积相研究及构造样式分析还可分析盆地沉积中心、生油层、盖层、储层等在时空中的变化规律.由于沉积盆地的升降波动过程直接影响着盆地的埋藏史、热史和生、排烃史,因此通过沉积波动过程的系统分析不仅能正确建立盆地演化的地质模型,还可以正确认识油气形成与分布规律,有效指导油气勘探.

Studying on the Differences of Sinian Natural Gas Pools between Weiyuan Gas Field and Ziyang Gas-Brone Area, Sichuan Basin

In this paper,taking the Permian stratum of the north Sichuan Basin as an example,combining the analysis method of sequence stratigraphy with the analysis method of wave processes,the quantized method that studies the imperfection of sedimentary record by using the analysis method of wave processes has been put forward.This method can describe quantificationally heave motion accurately during the course of basin evolution and can renew the course of sediment-denude without record in stratum and then analyse quantificationally the course of sediment-denude,calculate the erosion amount of discontinuity,and understand their distribution law of space-time.At the same time,a set of basal and important figures have been worked out,for example,the space distribution diagram of main unconformity,the contour diagram showing denuded amount,the contour diagram showing original ply,the denuded amount distribution diagram of structures of in different epoch.All of these figures are based on many actual drilled wells and the analysis of wave processes of manmade wells and the interpretation of seismic sections.The above analysis gives the basis of further study of basin systemic analysis and basin simulation,and also can specify the variety law of reservoir bed,centre of sedimentation,capping bed,source bed in space-time combined with the study of sedimentary facies and the analysis of tectonic style.The heave wave process of sedimentary basin directly influences buried history,heat history,create and blowout hydrocarbon history of basin.So,the analysis of wave processes can not only correctly set up the geological model of basin evolution,but also correctly recognize the law of the form and distribution of hydrocarbon,then instruct the exploration of oil gas effectively.