塔里木盆地阿克库勒凸起东南斜坡走滑断裂构造特征及油气地质意义

Tectonic characteristics of strike-slip faults in southeastern slope of Akkule uplift in Tarim basin,and its petroleum geological significance

塔里木盆地阿克库勒凸起东南斜坡发育大量走滑断裂。走滑断裂的几何学、运动学特征对油气的运移和富集起到了重要控制作用。本文以东南斜坡S118-AT22-YUKE2断裂、S113-AT13-YUKE3断裂、AT20断裂、AT18-YUKE5断裂为研究对象,依据中小尺度走滑断裂精细解析技术,对走滑断裂在不同层系的变形特征、平面分段性、断裂体系活动强度、后期活动性、通源性、演化模式和成因机制开展精细解析,结合生产动态资料研究其油气地质意义。阿克库勒凸起东南斜坡走滑断裂在垂向上呈深层线性断裂与浅层雁列式断裂组合的变形结构。中—下奥陶统发育的走滑断裂在平面上具有明显分段特征。阿克库勒凸起东南斜坡走滑断裂相对活动强度西强东弱,由北向南呈强—弱—次强的特征;晚海西期—燕山期断裂活动性近SN—NE向断裂体系强于NNE—NNW向断裂体系;断裂通源性受控于早期裂谷,主干断裂通源性优于次级断裂,NNE—NNW向断裂体系的主干断裂通源性优于近SN—NE向断裂体系,但次级断裂通源性较差。NNE—NNW向和近SN—NE向断裂体系都形成于中加里东期,NEE向断裂形成于晚加里东期—早海西期,东南斜坡走滑断裂经历了中加里东期、晚加里东期—早海西期、中晚海西期、印支期—燕山期多期构造活动垂向叠加,NNE向和近SN向主干断裂滑移方向相反是由于破裂方式的不同。阿克库勒凸起东南斜坡烃源岩排烃期为晚海西期—喜马拉雅期,断裂活动期与排烃期的耦合有利于油气充注;断裂活动强度控制了通源性和储集体规模,进而控制了油气富集程度。后期活动明显、断裂活动强、通源性好的走滑断裂是下一步勘探的有利目标。

A large number of strike-slip faults are distributed in the southeastern slope of the Akkule uplift in Tarim basin.The geometric and kinematic characteristics of strike-slip faults play an important role in controlling hydrocarbon migration and enrichment.S118-AT22-YUKE2,S113-AT13-YUKE3,AT20,AT18-YUKE5 faults are taken as the research object.Based on the theory of fine analysis technique of small and medium-sized strike-slip faults,detailed analysis is carried out on the layered deformation,plane segmentation,fault system activity intensity,late activity,source conditions,evolution mode and genetic mechanism of strike-slip faults.Then the petroleum geological significance is discussed based on production dynamic data.The strike-slip fault in the southeastern slope of Akkule uplift has a vertical deformation structure of deep linear fault combined with en echelon fault,and the middle-lower Ordovician strike-slip fault has obvious plane segment characteristics.The relative fault activity intensity of the southeastern slope is strong in the west and weak in the east,showing strong-weak-sub strong characteristics from north to south.The late activity of near SN-NE trending fault system is stronger than the NNE-NNW fault system in the Late Hercynian-Yanshanian period.The source condition of faults was controlled by the early rift.The source condition of main fault is better than the secondary fault.The source condition of main fault of NNE-NNW trending fault system is better than the SN-NE trending fault system,but the secondary fault is worse.The NNE-NNW trending fault system and SN-NE trending fault system were formed in the middle Caledonian,and the NEE fault was formed in the late Caledonian-early Hercynian.The strike-slip fault of the southeastern slope experienced the vertical superposition of the middle Caledonian,Late Caledonian-early Hercynian,middle-late Hercynian,and Indosinian-Yanshanian multi-stage tectonic activities.The opposite slip directions of NNE and SN main faults are due to the different fracture modes.The hydrocarbon expulsion period of source rock in the southeastern slope of Akkule uplift is in late hercynian-Himalayan age.The coupling of fault-active period and hydrocarbon expulsion period is favorable for oil-gas charging.The intensity of fault activity controls the faults source condition and reservoir size,and then controls the degree of oil and gas enrichment.The strike-slip faults with obvious late activity,intensity of fault activity and good source condition are favorable targets for further exploration.