云阳—涪陵地区长兴组—飞仙关组沉积相研究

Favorable Facies Belts of Changxing-Feixianguan Formations in Yunyang-Fuling Area

运用层序地层学的理论和方法,将云阳—涪陵地区长兴组—飞仙关组划分为4个三级层序,包括8个体系域,进一步建立相关层序地层格架。通过对层序地层格架内沉积相展布的研究,发现该地区长兴组—飞仙关组发育台缘礁滩和潮坪及台内礁滩有利储集相带,并受开江—梁平海槽的控制,沿海槽两侧呈条带状分布。此外,还受气候背景和台缘类型、台地部位及其类型以及海底高地貌的控制。在有利储集相带分布预测成果的基础上,结合多种地质信息进行综合分析,将研究区划分为5类有利勘探区带,即台缘礁区、台缘滩区、台缘潮坪区、台内礁区及台内滩区,其中台缘礁滩及潮坪区是最为有利的勘探区带和当前勘探的重点;台内礁滩区是台缘礁滩区的补充,可望取得突破。

Changxing-Feixianguan formations in Yunyang-Fuling area can be classified into four third-order sequences including eight system tracts according to sequence stratigraphy. Some corresponding sequence stratigraphic framework is further established. It is found from sedimentary-facies distribution that: (1) some favorable reservoir facies belts, including reef beach in the platform margin, tidal flat and reef beach within the platform, are developed in Changxing-Feixianguan formations; (2) these belts are controlled by the Kaijiang-Liangping Trough and are distributed in banding shape along both sides; (3) they are affected by climate, marginal type, platform location and type, and seafloor high landform. In addition, based on the prediction of faceis belt distribution and the comprehensive analysis of geological information, the study area can be divided into five favorable exploration blocks, including reef in the platform margin, beach in the platform margin, tidal flat in the platform margin, reef within the platform and beach within the platform. Both beach reef in the platform margin and tidal flat are not only the most favorable exploration blocks but also important exploration targets. And beach reef within platform can be as a supplement for making breakthrough.