准噶尔盆地莫索湾地区白垩系清水河组沉积演化与有利砂体展布

以三维地震、钻测井、岩心、测试化验等资料为基础,对准噶尔盆地莫索湾地区白垩系清水河组特别是“底砂岩段”重点油气储集层进行层序地层划分、沉积特征和砂体展布研究。认为:(1)清水河组发育高位体系域、湖侵体系域和低位体系域;其中,低位体系域主要发育浅水辫状河三角洲相,湖侵体系域发育滨浅湖-半深湖相,而高位体系域则发育浅水曲流河三角洲相。(2)“底砂岩段”中发育水下分流河道、河口坝、席状砂和分流间湾4种沉积微相类型;“底砂岩段”位于受北部物源控制的浅水辫状河三角洲前缘,可分为内前缘和外前缘;(3)结合区域沉积背景建立了清水河组浅水三角洲沉积微相模式,整体上,清水河组沉积演化过程为一套完整的湖平面升降演化沉积旋回。

Sedimentary evolution and favorable sandbody distribution of the Cretaceous Qingshuihe Formation in Mosuowan area,Junggar Basin

Based on 3D seismic data,well data,core observation and laboratory data,the study of sequence stratigraphic division,the sedimentary characteristics and sandbody distribution of the Cretaceous Qingshuihe Formation in Mosuowan area of Junggar Basin especially the bottom sandstone member which is the main hydrocarbon reservoir are carried out. It is concluded that: (1)The Qingshuihe Formation was divided into the highstand system tract,the transgressive system tract and the lowstand system tract. Shallow water braided river delta facies was developed in the lowstand system tract,shallow to semi deep lake facies was developed in the transgressive system tract,and shallow water meandering river delta facies was developed in the highstand system tract. (2)The “bottom sandbody member”consists of 4microfacies types,namely,underwater distributary channel,mouth bar,sheet sand and interdistributary bay,and is located in the shallow water braided river delta front that can be divided into inner part and outer part controlled by the north provenance. (3)The sedimentary microfacies model of shallow water braided river delta in the Qingshuihe Formation was constructed based on the regional sedimentary background,and we concluded that the sedimentary evolution process of the Qingshuihe Formation is a complete sedimentary cycle of lake-level fluctuation.