辽中凹陷古近系东三段湖底扇沉积特征及控制因素

辽中凹陷古近系东三段发育湖底扇沉积，为明确研究区湖底扇的沉积特征、发育控制因素及沉积展布特征，结合区域构造发育特征及古地貌分析，综合分析岩心、岩石学、测井响应、地震响应等特征。结果表明：研究区东三段主要发育湖底扇沉积体系，湖底扇可划分为内扇、中扇和外扇等3个沉积亚相及主水道、辫状水道等若干微相。湖底扇沉积特征受控于物源供给、古地貌及坡折带的分布，其中远源的三角洲是湖底扇的发育先决条件；古地貌提供了可容纳空间，控制了湖底扇的发育位置及规模；坡折带控制沉积物的沉积速率及湖底扇的调节与再分配。东三段沉积早期仅在B,C构造区发育3期湖底扇沉积；中期辫状河三角洲体系发育，大规模发育湖底扇沉积；晚期仅在中部和B构造区发育湖底扇沉积。综上可知，B构造区湖底扇展布面积大，砂体厚度大，储层物性好，垂向叠合性好，紧邻生烃中心，油气运聚条件优越，是有利的勘探目标。

Sedimentary characteristics and controlling factors of sublacustrine fans of the third member of Paleogene Dongying Formation in Liaozhong Sag

Sublacustrine fans are developed in the third member of Dongying Formation of Paleogene(Ed₃)in Liaozhong Sag.In order to clarify the sedimentary characteristics,controlling factors and sedimentary distribution characteristics of the sublacustrine fans in the study area,the characteristics of cores,petrology,logging response and seismic response were comprehensively analyzed in combination with regional structural development characteristics and paleogeomorphic analysis.The results show that sublacustrine fans are mainly developed in the Ed₃ of the study area.The sublacustrine fans can be divided into three subfacies such as inner fans,middle fans and outer fans,and several microfacies including main channels and braided channels.The sedimentary characteristics of sublacustrine fans are controlled by provenance supply,paleogeomorphology and the distribution of slope break zone.The distal delta is the prerequisite for the development of sublacustrine fans.The paleogeomorphology provides accommodation space and controls the location and scale of sublacustrine fans.The slope break zone controls the deposition rate of sediments,and the regulation and redistribution of sublacustrine fans.In the early stage of Ed₃,three stages of sublacustrine fans were only developed in structural areas B and C.In the middle stage,braided river delta system developed,and large-scale sublacustrine fans were developed.In the late stage,sublacustrine fans were only developed in the central and structural area B.The structural area B is a favorable exploration target with large sublacustrine fan distribution,large sand body thickness,good reservoir physical properties and good vertical superposition,and it is close to hydrocarbon generation center and favorable for hydrocarbon migration and accumulation.