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在层序地层学基础理论指导下 ,综合运用大量的地质、测井、地震及室内分析化验资料 ,对内蒙古钱家店凹陷侏罗系进行层序地层学研究。依据地震反射终止关系、古土壤的位置及分布、古生物化石断代位置、地震反射剖面上滨岸上超位置及迁移规律、沉积相、地层叠置型式等一系列特征识别层序边界、最大湖泛面和首次湖泛面。将上侏罗统划分为 4个层序 ,确定层序周期为 5～ 8Ma ,指出层序地层构型主要受盆地断裂活动和物源供给多少的影响。根据盆地西断东超的箕状特征 ,以“地形变化带”为界 ,确定首次湖泛面 ,以最远滨岸上超点确定最大湖泛面 ,进而将断陷湖盆沉积层序划分成低位体系域、湖侵体系域和高位体系域。详细描述了低位、湖侵和高位体系域中发育的近岸水下扇、辫状河三角洲、深水浊积扇及湖泊沉积特征和分布规律 ,结合石油地质综合评价和油气勘探实践 ,指出层序B(九佛堂组 )湖侵体系域盆地缓坡辫状河三角洲前缘砂体和盆地中央深水浊积扇砂体是寻找地层岩性圈闭的有利部位。
Under the guidance of the basic theory of sequence stratigraphy, a series of sequence stratigraphy of the Jurassic in the Qianjiadian Depression of Inner Mongolia has been carried out using a great deal of data of geology, logging, seismic and laboratory analysis. Based on the relationship between the termination of seismic reflection, the location and distribution of paleosol, the dating of paleontology fossils, the superposition and translocation along the shore of seismic reflection profile, sedimentary facies and stratigraphic superimposition patterns, And first lake flood surface. The Upper Jurassic is divided into 4 sequences, and the sequence sequence is determined to be 5 ~ 8Ma. It is pointed out that the sequence stratigraphic configuration is mainly affected by fault activity and source supply in the basin. According to the characteristics of the half-graben in the East Dachang ultra-basin, taking the “topographic change zone” as the boundary, the first flood surface is determined and the maximal lake flood surface is determined by the super-point on the farthest bank, then the sedimentary sequence of the fault basin is divided into Lowstand system tract, lacustrine system tract and highstand system tract. The paper describes in detail the characteristics and distribution of nearshore subaqueous fan, braided river delta, turbidite fan and lacustrine sediments developed in the lowstand, lakeshore and highstand system tract. Combined with the comprehensive evaluation of petroleum geology and oil and gas exploration practice, The gentle braided delta front sand body and the deep-water turbidite fan sand body in the B (Jiufotang Formation) lacustrine system basin are favorable sites for lithologic traps.