蠡县斜坡中北部沙二段—沙一段层序地层研究

STUDY ON THE SEQUENCE STRATIGRAPHY OF THE MEMBER2-MEMBER1 SHAHEJIE FORMATION IN THE NORTH-CENTRAL PART OF LIXIAN SLOPE

通过对研究区岩芯、地震、测井和录井等资料的综合研究,建立了沙二段—沙一段的层序地层格架,将其归为2个三级层序,划分出低位体系域、湖扩展体系域和高位体系域3种类型的6个体系域,并在此基础上进行了详细的沉积演化研究。工区以辫状河三角洲和滨浅湖滩坝沉积为主,沙二段平原亚相广布于斜坡外带,前缘亚相呈北东向沿斜坡中带展布;沙一段为广盆浅水环境,三角洲沉积范围较沙二段明显缩小,中期发育了一套全区最重要的烃源岩,受博野水系强物源的影响,仅在大百尺一带发育辫状河三角洲前缘沉积。斜坡中带毗邻生油洼槽的前缘砂体及雁翎、西柳地区的滩坝体系是成藏的有利区带。

Based on the comprehensive study on core,seismic and logging data,the sequence stratigraphy framework is built up.The strata of the Member 2 and Member 1 of Shahejie Formation can be divided into two third-order sequences,including six system tracts with three different types:low stand system tract,extension system tract and high stand system tract.And the depositional evolution of the system tracts is analyzed.The braided fluvial delta and sand bar and beach of shallow-shore lacustrine are the main facies.The braided fluvial delta plain distributes on the outer belt of the slope,and along the middle belt of the slope the braided fluvial delta-front is widely developed during the Member 2 of Shahejie Formation.While the Member 1 of Shahejie Formation has experienced the largest transgression from the Paleogene,the delta deposit is obviously decreased.Intermediate stage of the Member 1 of Shahejie Formation,the delta-front is developed only on the belt of Dabaichi,and the rest of the area is covered by source rocks.The braided fluvial delta-front sandbodies which include the sand bar and beach in Yanling and Xiliu,are in direct contact with oil generation depression and are the favorable exploration areas.