吉木萨尔凹陷二叠系梧桐沟组沉积演化规律

SEDIMENTARY EVOLUTION OF THE PERMIAN WUTONGGOU FORMATION IN JIMUSAER SAG,JUNGGAR BASIN

二叠系梧桐沟组是准噶尔盆地吉木萨尔凹陷重要的含油气层系之一,具良好的勘探前景。前人进行过不同层次的研究,在吉木萨尔凹陷东斜坡地区勘探程度相对较高,对于吉木萨尔凹陷梧桐沟组主要发育的沉积相类型一直存在争议。为满足梧桐沟组深化勘探的需要,在前人研究的基础上,此次采用地质和地球物理研究相结合的方式,将岩心观察描述、录井资料分析、测井响应特征和地震相、地震属性研究等综合应用,系统地开展了吉木萨尔凹陷梧桐沟组沉积相分析。研究结果表明:吉木萨尔凹陷二叠系梧桐沟组主要发育辫状河三角洲-湖泊沉积体系,东斜坡地区及北部地区发育多期辫状河三角洲;砂体呈退积式叠置,而砂体间的泥岩夹层及梧二段广泛发育的泥岩则作为局部及区域性盖层,这种高效的砂-泥储盖组合是岩性圈闭形成的良好基础。

The Wutonggou formation of Permian is one of the important hydrocarbon sequences in Jimusaer sagof Junggar basin, and it has good explorative prospects. Predecessors have had different levels of study about thisarea, but only in east slope of jimusar sag exploration degree is relatively high. Moreover, the main types of thesedimentary facies of Wutonggou formation in Jimusaer sag have been controversial. For the purpose of the re-quirements of deepening petroleum exploration, on the basis of previous researches, this paper adopted the com-bination of geological and geophysical research, with comprehensive application of core observation, logging dataanalysis, well logging response characteristics, seismic facies, seismic attributes and so on, and sedimentary fa-cies analysis of the Wutonggou formation in Jimusaer sag was systematically carried out. The results showed thatthe main sedimentary facies were braided delta-lake sedimentary system in the Permian Wutonggou formationand there were several braided river deltas developed in east slope and north area. The sand body showed retro-gradation type superimposed, and mudstone interlayer between the sand body and mudstone extensively develop-ing in the Wu-2 member could be served as local and regional cap rock. The efficient sand-mud assemblageshas been provided with good bases for the formation of lithologic traps.