前陆盆地斜坡区坡折带对沉积体系的控制作用——以四川盆地川中地区须家河组四段为例  

Controlling effect of slope break zone on sedimentary systems in the slope area of foreland basin:A case study of the 4th Member of Xujiahe Formation in central Sichuan basin

作　　者：厚刚福 刘占国 王小娟[2] 陈星渝 郑超[2] 袁纯 宋兵 伍劲 王波 董雨洋 刘少治 王少依 HOU Gangfu;LIU Zhanguo;WANG Xiaojuan;CHEN Xingyu;ZHENG Chao;YUAN Chun;SONG Bing;WU Jin;WANG Bo;DONG Yuyang;LIU Shaozhi;WANG Shaoyi(Petrochina Hangzhou Research institute of Geology,Hangzhou,Zhejiang 310023,China;Research Institute of Exploration and Development,PetroChina,Southwest Oil&Gasfield Company,Chengdu,Sichuan 610041,China)

机构地区：[1]中国石油杭州地质研究院,浙江杭州310023 [2]中国石油西南油气田分公司勘探开发研究院,四川成都610041

出　　处：《地质学报》2024年第10期3106-3116,共11页Acta Geologica Sinica

基　　金：中国石油“十四五”科技重大专项“多类型储集体发育机制与储集能力定量评价技术研究”(编号2021DJ0402);“深层超深层有效储层形成主控因素与预测技术研究”(编号2021DJ0202)资助的成果。

摘　　要：为了明确前陆盆地斜坡区坡折带对沉积体系的控制作用,厘定沉积体系展布规律,以四川盆地川中地区须家河组四段为例,采用地层厚度法恢复了古地貌,刻画了坡折带,并通过岩芯观察、测井相及地震相分析,识别了前陆斜坡区沉积微相类型,在此基础上,通过沉积微相与古地貌叠合分析,提出前陆盆地斜坡区大型坡折带控制沉积体系与微相砂体分布。研究结果表明:四川盆地川中地区须家河组四段沉积期为前陆斜坡背景,发育大型坡折带,在此背景下发育远源辫状河三角洲沉积体系,以辫状河三角洲前缘亚相沉积为主,可进一步识别出内前缘带和外前缘带,以及水下分流河道、砂坝、分流间湾和席状砂等4种沉积微相。坡折带之上主要发育三角洲内前缘带水下分流河道微相,坡折带之下主要发育三角洲外前缘带水下分流河道与砂坝复合砂体。坡折带之下的砂坝微相砂体具备良好的侧向遮挡条件,顶底板条件优越,有利于形成岩性圈闭,且紧邻川西凹陷烃源灶,为下一步最有利勘探领域。To clarify the control effect of slope break zones on sedimentary systems in the foreland basin slope area and determine the distribution pattern of these systems,the fourth member of the Xujiahe Formation in the central Sichuan basin was used as a case study.Ancient landforms were reconstructed using the impression method,and slope break zones were identified.Subsequently,core observation,logging facies analysis,and seismic facies analysis were carried out todelineate sedimentary microfacies in the foreland slope area.By integrating sedimentary microfacies and reconstructed ancient landforms,this research proposes that large-scale slope break zones exert significant control over the distribution of sedimentary systems and associated sand bodymicrofacies.Results indicate that the sedimentary period of the fourth member of the Xujiahe Formation in the central Sichuan basin was characterized by a foreland slope setting,marked by the presence of large slope break zones.In this background,a far-source braided river delta sedimentary system developed,mainly composed of braided river delta front subfacies.Further differentiation reveals distinct inner and outer delta front belts,encompassing four sedimentary microfacies,including mouth bars,underwater distributary channels,interdistributary bays,and sheet sand.Above the slope break zone,underwater distributary channel microfacies are prevalent in the inner delta front zone.Conversely,below the slope break zone,composite sand bodies composed of underwater distributary channels and river mouth bars dominate the outer delta front zone.The Hekou dam,situated below the slope break zone,exhibits favorable lateral shielding conditions and superior roof and floor conditions,which are conducive to the formation of lithologic traps.Its proximity to hydrocarbon source rocks in the western Sichuan depression renders it a highly prospective target for future exploration endeavors.

关 键 词：四川盆地 须家河组 前陆盆地 坡折带 砂坝 岩性圈闭 致密气 

分 类 号：P618.13[天文地球—矿床学]