【摘要】 准噶尔盆地中部4区块(以下简称"准中4")中侏罗统头屯河组砂体储层主要沉积于缓坡背景下湖泊-浅水三角洲-曲流河体系,是重要的石油勘探开发层系。本文以高分辨率层序地层学和沉积学为理论指导,利用岩心、测井和地震资料对中4区块头屯河组进行层序地层研究,根据识别出的多级旋回界面将中4区块头屯河组划分为1个长期旋回、3个中期旋回、10个短期旋回,并建立层序格架。结合测录井响应、岩心分析、粒度分析、地震切片划分出18种沉积微相并优选物性较好的微相类型;结合测录井响应、地震切片及平均砂岩累积厚度、平均砂岩密度、平均分层系数对砂体发育规模及连通性进行研究。结果表明:准中4区块头屯河组垂向从头1段到头3段沉积充填呈现滨浅湖-三角洲前缘向三角洲平原-泛滥平原过渡,由"大前缘、小平原、网状分流河道"向"大平原、小前缘、枝状分流河道"演化的特点;识别出的成因砂体类型中以边滩砂体(曲流河边滩砂在头屯河组少量发育)、分支河道砂体、水下分流河道砂体物性最好,有利于储层发育;自头1段到头3段,垂向砂体连通性逐渐变好,横向砂体连通性逐渐变差;缓坡背景下研究区沉积演化受湖平面变化控制,在以上研究基础上通过均方根振幅属性提取及最大波峰振幅属性切片共预测出16个有利砂体约108 km~2。更多还原

【Abstract】 The Middle Jurassic Toutunhe Formation sandstone reservoir, which was deposited in a lake-shallow delta-meandering river sedimentary system with gentle slope background, is an important petroleum exploration and development horizon in Block 4 of Middle Junggar Basin. Based on the theory of high-resolution sequence stratigraphy and sedimentology, the authors investigated the sequence stratigraphy, sedimentary evolution and development characteristics of sandstone by comprehensive analysis of core photograph, logging and seismic data. According to the identified multi-stage cyclic interfaces, the Toutunhe Formation in Block 4 comprises one long-term stratigraphic base-level cycle(LSC), which can be divided into three middle base-level cycles(MSC1, MSC2, MSC3) and ten short cycles(SSC1-SSC10). In combination with logging response, core analysis, grain size analysis and seismic slice, 18 kinds of sedimentary microfacies were recognized and better microfacies types were selected; based on logging response, seismic slice and average cumulative thickness of sandstone, average density of sandstone and average stratification coefficient, the authors studied the development scale and connectivity of sandstone body. It is found that the sediment filling of Toutunhe Formation in Block 4 of Middle Junggar Basin is characterized by the transition from shore-shallow lake-delta front to delta plain-flood plain and the evolution from "big front-small plain delta(BFBPD) with network distributary channel" to "big plain-small front delta(BPBFD) with branch distributary channel". Point bar, branch channel and underwater distributary channel sand bodies, which have the best physical properties, are favorable for development of high-quality reservoir. The vertical connectivity of sand bodies gradually increases but the lateral connectivity decreases from MSC1 up to MSC3. Besides, the evolution of sedimentation in the study area is controlled by lake level changes under gentle slope background. Based on the above research, the authors delineated 16 favorable sand bodies covering an area of about 108 km~2 by extracting the root mean square amplitude attribute and slicing the maximum peak amplitude attribute.更多还原