苏北盆地溱潼凹陷戴一段沉积-层序特征及其对岩性勘探的指示意义

为厘清溱潼凹陷戴一段岩性勘探有利层段及区带这一关键地质问题，应用高分辨率层序地层学、沉积学等基础理论、技术方法，综合地震、钻井岩心及测井资料，对溱潼凹陷戴一段进行了沉积-层序研究，识别出层序界面及洪泛面两类转换面，并进一步划分为1个长期、5个中期旋回层序，深凹带5个中期旋回层序发育齐全，中-外坡逐渐减少至2个，明确了泰州凸起是戴一段的主物源方向，戴一段发育扇三角洲沉积体系，沉积相带展布受物源、基准面升降共同控制。沉积-层序综合研究表明纵向上戴一段MSC1、MSC2、MSC3时期泥岩隔层发育、储盖组合有利，是岩性勘探最有利层段；平面上相带的展布决定了岩性勘探的有利区带，西斜坡的蔡家堡-陈家舍、帅西、帅垛及帅北地区处于多期扇体前缘砂岩尖灭区，是岩性/构造-岩性圈闭勘探的重点区域。

Depositional characterristics of the first member of Dainan formation in Qingtong sag,Subei basin and their significance to lithological exploration

By using high resolution sequence stratigraphy and sedimentology as tools upon the basis of seismic, coreing and well logging data, we carefully studied the first member of Dainan formation in the Qingtong sag in order to find out the favorable layers for lithology exploration. Two kinds of transitional surface, i.e. the sequence boundary and flooding boundary are recognized. The exploration target layer may be divided into one long-term cycle and five intermediate cycles which may be reduced from five to two from the deep sag to the slop surrounded.The Taizhou uplift was the main source of sediments then and theDainanFormation is a kind of fan deltaic deposits.The distribution of sedimentary facies belts are controlled by both the sediment source and base level changes. In the vertical direction, however, mudstone interlayers were deposited in the stages of MSC1, MSC2, MSC3 as favorable cap rocks.All the data indicates that the 1st member of the Dainan formation is the most favorable exploration interval.Spatially, facies belt distribution is the key controlling factoron hydrocarbon accumulation. Caijiabao-Chenjiashe, Shuaixi, Shuaiduo and Shuaibei blocks on the west slope where fan front sandbodies frequently pinchout are the most favorable region for lithological and/or structural-lithological traps.