Abstract: The prospecting degree is low,and the subtle reservoirs are very common in the central part of Junggar Basin.The principles and methods of high-resolution sequence stratigraphy were used to predict the distribution rules of the Jurassic reservoir.Based on drilling data and seismic calibration results,the Jurassic System was divided into four long-term base-level cycles bounded by unconformity and sedimentary transform surfaces.There are mainly three types of short-term base-level cycles,which control the formation of coastal-shallow lagoon sheet sand,mouch bar and subaqueous distributary channel sediments of braided stream delta front.According to stacking patterns of short-term cycles and calibration of logs restrained by key interfaces,a log interpretation model for the Jurassic medium-term base-level cycles was established,and 14 medium-term cycles were distinguished.Under the control of dynamic variation of the accommodation-sediment ratio,the favorable reservoirs were usually developed during the rising stage of the medium-term base levels.The sandstones deposited during descending stage are laterally interconnected,while the lithologic reservoirs can not be formed easily in this stage.The drilling data confirm that the mid-lower part of SQ3 sequence is the main interval for development of lithologic reservoirs.

Key words: Junggar Basin, Jurassic System, sequence stratigraphy, base-level cycle, sedimentary facies, lithologic reservoir

摘要： 针对准噶尔盆地腹部地区勘探程度低、砂体与油气分布具有较强隐蔽性的特点,将高分辨率层序地层学的原理和方法用于预测该区侏罗系储集砂体分布规律.根据钻井和地震标定结果,以不整合面和沉积作用转换面为界,将侏罗系划分为4个长期基准面旋回.短期基准面旋回主要有3种构成样式,形成了辫状河三角洲前缘水下分支河道、河口坝和滨浅湖席状砂3种沉积微相类型.根据短期旋回的叠加样式及关键界面对测井曲线的标定结果,建立了侏罗系中期基准面旋回的测井解释模型,将其划分为14个中期基准面旋回.受基准面和可容纳空间与沉积物供给量比值动态变化的控制,有利储集相带主要分布于中期基准面上升期,基准面下降期的砂体横向连通性好,不易形成岩性油藏.钻井证实SQ3层序的中下部是岩性油藏的主要发育段.

关键词: 准噶尔盆地, 侏罗系, 层序地层学, 基准面旋回, 沉积相, 岩性油藏