【摘要】 在现代沉积学和地震沉积学理论指导下,综合应用11口岩心资料和大量地球物理资料,将松辽盆地齐家地区青山口组划分为3个长期旋回和6个中期旋回,确立青山口组主要发育湖盆浅水三角洲沉积体系。青山口组浅水三角洲由成熟度较高的中细砂岩组成,发育反映较强水流作用形成的沉积构造以及间断正韵律,分支河道砂体发育,累计砂体厚度达数十米,分布范围广,向湖盆中央方向延伸数十公里。三角洲前缘可细分为內前缘和外前缘。三角洲內前缘水下分支河道连续性好、延伸远;三角洲外前缘水下分支河道连续性差,被改造后形成前缘席状砂。基于浅水三角洲发育主控因素分析,建立了干旱和湿润气候条件下形成的浅水三角洲沉积模式。利用地震沉积学的地层切片刻画了浅水三角洲沉积砂体的枝状形态和大面积分布特征,指出近油源和临近断层的三角洲前缘砂体为有利勘探开发目标。更多还原

【Abstract】 Under the guide of modern sedimentology and seismic sedimentology,combined with the comprehensive analysis of core data from more than ten wells and geophysical data,Qingshankou Formation is divided into 3 long-term cycles and 6 medium-term cycles in Qijia area,Songliao Basin. The 3 long-term cycles,SQ1,SQ2 and SQ3 correspond to the members,Qing Ⅰ,Qing Ⅱ and Qing Ⅲ,and the time scale of medium-term cycle is about 0. 5 ~1. 5 Ma,with thickness ranging from 45 m to 116 m. Shallow-water delta which consists of high-maturity fine-grained sandstone is mainly developed in Qingshankou Formation,and erosion surface reflecting stronge flow action,parallel beddings and long-scale cross beddings are well developed. Distributary channel sandstone is well developed in the shallow-water delta sedimentary system,with single channel thickness about several meters. The accumulative thickness of distributary channels can reach to tens of meters with a large distributing area,extending to the center of lacustrine basin over tens of kilometers. The development of subaqueous distributary channel of shallow-water delta is closely related to the base level( lake level) change. In the early stage of rising semi-cycle and the late stage of falling semi-cycle,the fluviation is significant and the channel sandstone which can extend towards the center of lacustrine basin more than 50 kilometers is well developed,with large accumulative thickness of compound sandbody( 17~ 28 m) and high sandstone to strata ration( 78% ~ 88%). In the late stage of rising semi-cycle and the early stage of falling semi-cycle,the lake level rises and the fluviation becomes weak,resulting in the extending distance of distributary channel less than 30 kilometers with small accumulative thickness of compound sandbody( 5 ~ 12 m) and low sandstone to strata ration( 22% ~ 45%). Delta front can be divided into inner front and outer front. The subaqueous distributary channel in inner front has good continuity and extends further,whereas the subaqueous distributary channel in outer front has poor continuity and sheet sand is well developed. Two typical sedimetanry models of shallow-water delta,delat plain well developed in humid climate and detla front well developed in arid climate,are established in Qijia area,Songliao Basin. Stratal slices from seismic sedimentology are applied to display the branchlike sandstone dispersal pattern of shallow-water delta and the characteristics of widely distribution. This study also points out that the detla front channel sandstone which is near to oil source and faults would be the favorable exploration targets.更多还原