鄂尔多斯盆地南部S205—S102井区长6油层组沉积相特征

S205—S102井区是鄂尔多斯盆地南部延长组的一个新探区,长6油层组勘探时间短、研究程度低。主要从岩心、薄片、分析化验、测井、录井等资料入手,在系统分析岩石学、粒度特征、沉积构造和测井曲线等沉积相标志的基础上,结合区域沉积背景,对鄂尔多斯盆地南部S205—S102井区长6油层组沉积相类型及特征进行研究。研究结果表明:长6油层组属于水下还原环境的重力流—湖泊沉积体系,主要发育重力流相和湖泊相,包括砂质碎屑流、浊积体和半深湖—深湖3种亚相,舌状体、舌状体间、浊积水道、浊积水道间(边缘)和半深湖—深湖泥(湖泥)5种微相;浊积水道呈宽条带状,呈北东—南西向展布于研究区中部,砂质碎屑流舌状体多孤立叠置于浊积水道之上,半深湖泥以包围重力流沉积之势分布于研究区中西部和东部;长6_4亚油层组孤立状舌状体最为发育,长6_3亚油层组浊积水道最宽,长6_1亚油层组舌状体连续性最好且砂体最厚,浊积水道与舌状体叠加之处砂体最为发育。研究结果可为该区块或邻区的勘探与开发提供理论基础。

CHARACTERISTICS OF THE SEDIMENTARY FACIES FOR OIL GROUP CHANG 6 IN WELL BLOCK S205-S102 IN SOUTH ORDOS BASIN

Well Block S205-S102 is the new explored region in Yanchang Formation of South Ordos Basin,Oil Group Chang 6 is characterized by the short explored time and low researched degree.With the help of the core,thin section,analytical test,well & mud logging and so on,on the bases of the systematically-analyzed depositional symbols of the petrology,grain size characteristic,sedimentary structure and well-logging curves and so on,the regional sedimentary background was summarized and moreover the researches on the depositional phases and characteristics were conducted for Oil Group Chang 6 in Well Block S205-S102 of South Ordos Basin.The study achievements show that the group belongs to the gravity flow-lake depositional system with underwater reductive environment,the gravity flow facies and lacustrine facies are mainly developed,including three sub-facieses:sandy debris flow,turbidity body and semi-deep &deep lake,and moreover five kinds of the microfacieses:lobe,interlobe,turbidity channel,the edges among the turbidity channel and semi-deep & deep lake mud;The turbidity channel is widely stripped with NE-SW trending located in the middle study area,the sandy debris flow lobe is more isolated overlay on the turbidity channel,the semi-deep lake mud with the trending of surrounding the gravity flow is located in the central and western parts of the study area;The isolated lobe is developed best in Sub-oil Group Chang 64,the widest turbidity channel is located in Sub-oil Group Chang 63,the lobe in Sub-oil Group Chang 61 with the best connectivity is the thickest part of the sandbody,the sandbody in the turbidity channel overlaid by the lobe is best developed.The study achievements can provide theoretical basis for the exploration and development of the block or nearby regions.