川东地区飞仙关组沉积模式对储层展布特征的影响

INFLUENCES OVER RESERVOIR SPREADING CHARACTERISTICS BY SEDIMENTATION MODELS OF FEIXIANGUAN FORMATION IN EAST SICHUAN REGION

在三叠世早期 ,四川盆地继承了晚二叠世的海盆特征。在川东地区飞仙关组和长兴组之间没有明显的沉积间断 ,但二者岩性存在差异。川东地区飞仙关组的实钻表明 ,在以开江———梁平地区为中心 ,形成了一个不对称的凹陷区域。以这一凹陷区为界 ,其两侧沉积环境和地层特征有明显的不同。以现阶段的勘探认识和拥有的资料及目前的研究结果 ,整个川东地区飞仙关组的沉积环境及演变是在碳酸盐岩台地上的变化 ,其沉积模式为“浅海碳酸盐岩台地”模式。这种古地理格局控制了飞仙关组的沉积特征 ,以至于以中央凹陷区为界 ,在两侧形成了不同的储层类型和展布特征 ,不同类型的鲕滩储层分布受沉积相的控制明显并有一定的层位性。

During the early stage of Triassic epoch, Sichuan Basin inherited the characteristics of late-Permian marine basin. There was no obvious depositional hiatus between Feixianguan and Changxing formations in east Sichuan region, but the lithological differences between them both still existed. The actual drilling in Feixianguan formation in east Sichuan region showed that an asymmetric depression area had been formed with Kaijiang-Liangping region as its centre. The depositional environment and stratigraphical characteristics in these both sides were obviously different, if taking this depression as boundary. With present exploratory recognition, the possessed data, and current research results, the depositional environment and evolution of Feixianguan formation in the whole east Sichuan region is its change on carbonate rock platform, its sedimentation model is that of 'neritic carbonate rock platform.' This paleogeographical pattern has controlled the depositional characteristics of Feixianguan formation, to such an extent as to have formed different reservoir types and spreading characteristics on both sides with the central depression area as its boundary. The distribution of oolitic bank reservoir of different types is obviously controlled by sedimentary facies and has a definite horizoning nature.