渤海湾盆地歧北凹陷古近系沙二段复合三角洲内部结构及空间演化  

Inner Structure and Spatial Evolution of Complex Delta of the Second Member of Shahejie Formation of Paleogene in Qibei Sag,Bohai Bay Basin

作　　者：鲁超[1] 焦养泉[1,2] 吴立群[1] 吕琳[1] 

机构地区：[1]中国地质大学资源学院,湖北武汉430074 [2]中国地质大学构造与油气资源教育部重点实验室,湖北武汉430074

出　　处：《现代地质》2010年第2期311-320,共10页Geoscience

基　　金：中国石油大港油田和中国地质大学(武汉)合作项目"歧口富油气凹陷结构构造;层序地层及沉积体系研究"

摘　　要：对歧北凹陷三角洲进行分尺度研究。首先,通过各种地震属性的应用、地震相的追踪和砂分散体系的分析,发现复合三角洲分为西部三角洲和迁移的东部三角洲。然后,利用地震相的追踪能识别出歧北凹陷沙二段三角洲具有类似"s"型前积的反射特征,这是三角洲朵体侧向迁移的地震反射特征。在发现的侧向迁移现象基础上,对地震剖面上侧向迁移的每一个同相轴进行平面上追踪,控制每一个期次的迁移的朵体的平面展布范围,最终获得多个期次朵体的平面展布及演化,发现东部三角洲在沙二段低位体系域时,共向东迁移6次;在沙二段湖扩-高位体系域时,共向东迁移4次。西部三角洲持续垂向加积。侧向迁移现象的存在使得东部三角洲存在不同于其他三角洲的非均质性特征,砂体呈正韵律和反韵律的交互。东部三角洲的孔隙度整体相对较低,平均值14%,低于西部三角洲的平均值24.4%;该沉积类型的总平均渗透率较低,为0.017 2×10-3μm2,低于西部三角洲的0.037 5×10-3μm2;碳酸盐岩含量较高,平均值为13.5%,高于西部三角洲的平均值9.6%。Research on deltas in Qibei sag can be done on different scales.After the works of the application of seismic attributes,the tracing of seismic facies and the analysis of the sand distributed system,we find that the composite delta is divided into western part and migratory eastern part.The seismic facies present that there is a similar ＂s＂-type foreset reflectance characteristics of the delta of the second member of Shahejie Fomation in Qibei sag,which is seismic reflection characteristics of lateral migration of delta.Based on the discovery of the phenomenon of lateral migration,we track the axes in seismic profiles in plane to determine the scope of the the migratory delta in plane of each period of time,finally acquire the area and evolution of the delta with all the periods of time,and find that in the lowstand systems tract of the second member of Shahejie Fomation the East Delta migrate eastwardly six times while in the highstand systems tract the East Delta migrate eastwardly four times.The West Delta continually deposits vertically.The existence of the phenomenon of lateral migration makes the East Delta has different heterogeneity characteristics from others,sandstone possess interaction of positive rhythm and counter-rhythm.Porosity which as a whole is relatively low with an average 14% in East Pelta,is lower than the average of 24.4% in the West Delta;the average sediment permeability of this type,which is 0.0172×10-3μm2,is lower than that of the West Delta which is 0.037 5 × 10-3 μm2;content of carbonatite with an average of 13.5% in East Delta,is higher than that with the average of 9.6% in the West delta.

关 键 词：复合三角洲 内部结构 沙二段 歧北凹陷 

分 类 号：TE121.3[石油与天然气工程—油气勘探]