准噶尔盆地阜东斜坡带头屯河组基准面旋回和砂体分布规律

Characteristics of base-level cycles and sand body distribution of Toutunhe Formation in Fudong slope zone,Junggar Basin,China

中侏罗统头屯河组系准噶尔盆地东部阜东斜坡带最重要的勘探层系。以精细的单井沉积相和高分辨率层序分析为基础,从头屯河组中划分出1个长期、3个中期、10个短期基准面旋回层序。以长期旋回层序底界面、顶界面和最大湖泛面为等时对比标志,中期和短期旋回层序为等时地层对比单元建立地层格架,对地层格架中的小层砂体进行劈分和追踪对比,结果表明小层砂体的分布规律和储集性主要受中期基准面旋回控制。结合区域地质背景资料和多属性地震相分析成果编制的层序-岩相古地理图,进一步显示砂体集中分布在研究区中西部和东南部2个辫状河三角洲沉积体系的前缘亚相带,以厚度大和延伸稳定的水下分流河道砂体为有利勘探目标。

The Middle Jurassic Toutunhe Formation is the main exploration layer in the Fudong slope zone in the east of Junggar Basin.Based on the high-resolution sequence stratigraphy and precise sedimentary facies division of single wells,one long-term base level circle,four mid-term base level circles and ten short-term base level circles are divided from Toutunhe Formation.This paper takes the mid-term and short-term base level circles as strata correlation units to build the strata framework with many isochronic comparison marks such as bottom and top interfaces of the long-term base level circle and the maximum flooding surface,and made division and tracing comparison of the substrata sand bodies in this framework.The result shows that the distribution and reservoir quality of the substrata sand bodies are main controlled by the mid-term base level circle.The sequence-based lithofacies-paleogeography map made by analysing the regional geology background data and multiattributes seismic facies further points out that the front subfacies sand bodies of the delta sedimentary system are mainly distributed over the center-west and east-south of study area,and the sand bodies of the stably extensive underwater distributary channels with great thickness are the favorable exploration targets.