柴达木盆地西部红狮凹陷第三系下干柴沟组层序地层格架

SEQUENCE STRATIGRAPHIC FRAMEWORK OF THE LOWER GANCHAIGOU FORMATION IN HONGLIUQUAN-SHIZIGOU AREA, WESTERN QAIDAM BASIN

柴达木盆地西部红狮凹陷是青海油田公司的主要采油区 ,下第三系下干柴沟组是区内主要目的层段之一。以Cross的高分辨率层序地层学理论为指导 ,根据露头剖面和钻井资料 ,对区内下干柴沟组进行了详细的层序地层研究 ,共识别出 15个三级层序 ,4个超层序。在连井剖面的层序地层对比基础上 ,建立了该区的地层格架 ,并揭示出这 4个超层序中上升半旋回的水下冲积扇、低水位期湖底扇、辫状河流相以及下降半旋回扇三角洲相中的砂砾岩是红狮凹陷下第三系有利储集岩的分布区 ,最大湖泛期密集段暗色泥岩是该区主力烃源岩的分布区。

Hongliuquan-Shizigou Depression is located in western Qaidam Basin,which is a major oil-production area of Qinghai Oil-field Corporation. The Lower Ganchaigou Formation of the Lower Tertiary is one of the most important target-strata for oil exploration. Guided with the theory of high-resolution sequence stratigraphy and based on outcrop-sections and well logs, the sequence stratigraphic system of the Lower Ganchaigou Formation has been constructed, which is composed of 15 third-order sequences and 4 super-sequences, and the sequence stratigraphic framework has been discussed.The result opens out that the favorable reservoirs of the Lower Ganchaigou Formation in the study area are the sandstones and conglomerates developed in the subaqueous fan facies, the lacustrine floor fan turbidite facies of low water and the braided stream and the major hydrocarbon-producing rocks are the dark condenses of the largest lacustrine-deluge.