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塔里木盆地雅克拉断凸下侏罗统形成于断凸沉降期,不同时期的区域构造活动对沉积的控制作用有所差异,从而表现出不同的沉积特征。根据测井解释结果结合岩性资料,将研究区下侏罗统划分为4个砂组,分别从碎屑组分、单井相、物源及平面沉积相、纵向地层对比等方面进行典型沉积特征及差异分析。下侏罗统自下而上发育辫状河三角洲前缘、辫状河三角洲平原和浅湖3种亚相,共有3类不同母岩性质的物源体系,且不同沉积时期物源供给方式和供给量差异显著:3和4砂组沉积时期为三角洲前缘河道砂沉积,且3类物源供给丰富,平面沉积相展布呈现以沙参2和沙4井区为代表的哑铃形,与有效储层厚度分布形态相符;2砂组沉积时期过渡为三角洲平原沼泽环境,物源供给来源减少,其规模明显减小;1砂组沉积时期经历了由沼泽相到浅湖相的过渡,物源供给几乎中断。研究区各微相沉积特征显著,广泛发育物性较好的水下分流河道微相,其发育区是有利储集区。
The Lower Cretaceous subfacies of the Yakela fault in the Tarim Basin formed during the overturning and subsidence. The regional tectonic activities in different periods had different control over the sediments, showing different sedimentary characteristics. According to the logging interpretation results and lithology data, the Lower Jurassic in the study area is divided into four sand groups, which are typical sediments from the aspects of detrital components, single well facies, provenance and planar sedimentary facies, and longitudinal stratigraphic correlation Features and differences analysis. The lower Jurassic develops bottom-up braided river delta front, braided river delta plain and shallow lake, and has three types of source systems with different lithofacies, and different sedimentary source supply modes and The sediment supply in the 3 and 4 sandstones is sediment of the delta front channel, and the three types of provenances are abundant in supply. The distribution of the plane sedimentary facies presents the dumbbell shape represented by the Shashen 2 and Sha 4 well areas, The distribution of reservoir thickness is consistent with each other. During the depositional period of No.2 sandstone group, the delta plain swamp environment transforms into a delta plains marsh environment, and the source of the source rocks decreases. The scale of the sandstone sediments decreases obviously. During the sedimentary period of Group 1 sandstone experienced the transition from marsh facies to shallow lake facies, Supply is almost interrupted. The microfacies of the study area are characterized by significant sedimentary facies, extensively developed submarine distributary channel microfacies with good physical properties, and its development zone is a favorable reservoir area.