坳陷湖盆古地貌对沉积体系的控制作用——以准噶尔盆地中部侏罗系三工河组二段一砂组为例

为了明确坳陷湖盆古地貌对沉积体系的控制作用，认识沉积体系展布规律，优选下一步勘探领域，以准噶尔盆地中部侏罗系三工河组二段为例，采用地层厚度法恢复了古地貌，细化了古地貌单元，并通过岩芯观察，识别了沉积微相，在此基础上，通过古地貌单元与沉积微相叠合分析，提出了坳陷湖盆沉积期古地貌对沉积体系、沉积微相和岩性圈闭的形成具有重要的控制作用。研究结果表明：准噶尔盆地中部三工河期为隆凹相间的古地貌格局，具有水下古低凸、水下古沟槽、古坡折和水下古平台等4类古地貌单元，发育湖泊-三角洲沉积体系，可进一步识别出水下分流河道、分流间湾、席状砂和砂质碎屑流微相。水下古沟槽充填水下分流河道微相砂体，水下古低凸主体部位发育分流间湾相泥岩，古坡折之下的水下古平台发育砂质碎屑流砂体。水下古低凸翼部发育的水下分流河道砂体向低凸方向超覆尖灭，水下古平台发育的砂质碎屑流砂体呈“泥包砂”结构，储层性质较优，岩性圈闭条件好，成藏条件优越，为下一步最有利勘探领域。

Analysis on controlling effect of palaeogeomorphology on sedimentary system: a case study of Jurassic Sangonghe Formation in the hinterland of Junggar basin

In order to clarify the control of paleogeomorphology on sedimentary system in the depression basin, implement the distribution of through the superposition analysis of paleogeomorphic units and sedimentary microfacies, it is proposed that the underwater distributary channel sand body developed in the underwater ancient trench is conducive to the formation of updip pinch-out lithologic trap; The sandy clastic flow sandbody developed in the underwater paleo-platform are favorable for the formation of lenticular lithologic traps. The results show that: the hinterland of Juggar basin during Sangonghe period is a paleogeomorphic pattern of uplift and depression alternation, which has four types of paleogeomorphic units: underwater paleo low uplift, underwater paleo groove, paleo slope break and underwater paleo platform. The delta sedimentary system is developed, which has the characteristics of relatively fine grain size, relatively deep water body and far delta extension. Sandy clastic flow sandbody are developed in Modong platform, Shawan platform and Fukang platform, and underwater distributary channel sandbody are developed in the wings of Shinan low convex, Xiayan low convex, Sangequan low convex, Shidong low convex, Dinan low convex, zhengshacun low convex and Mosuowan low convex, with good reservoir and lithologic trap conditions and favorable reservoir forming conditions, which are the most favorable exploration areas in the next step.sedimentary system, and optimize exploration field in the next step, taking the second member of Jurassic Sangonghe Formation in the hinterland of Junggar Basin as an example, the paleogeomorphology is restored by using the stratum thickness method, the paleogeomorphic units are refined, and the sedimentary micro-facies are identified by core observation. On this basis, through the superposition analysis of paleogeomorphic units and sedimentary microfacies, it is proposed that the underwater distributary channel sand body developed in the underwater ancient trench is conducive to the formation of updip pinch-out lithologic trap; The sandy clastic flow sandbody developed in the underwater paleo-platform are favorable for the formation of lenticular lithologic traps. The results show that: the hinterland of Juggar basin during Sangonghe period is a paleogeomorphic pattern of uplift and depression alternation, which has four types of paleogeomorphic units: underwater paleo low uplift, underwater paleo groove, paleo slope break and underwater paleo platform. The delta sedimentary system is developed, which has the characteristics of relatively fine grain size, relatively deep water body and far delta extension. Sandy clastic flow sandbody are developed in Modong platform, Shawan platform and Fukang platform, and underwater distributary channel sandbody are developed in the wings of Shinan low convex, Xiayan low convex, Sangequan low convex, Shidong low convex, Dinan low convex, zhengshacun low convex and Mosuowan low convex, with good reservoir and lithologic trap conditions and favorable reservoir forming conditions, which are the most favorable exploration areas in the next step.