湖南保靖地区下志留统重力流沉积特征及沉积模式  

Sedimentary characteristics and models of early Silurian gravity flow deposits in Baojing area of Hunan Province

作　　者：李斌 胡博文 罗群[2] 晋长昊 

机构地区：[1]神华地质勘查有限责任公司,北京100022 [2]中国石油大学(北京),北京102249

出　　处：《油气地质与采收率》2017年第6期7-16,共10页Petroleum Geology and Recovery Efficiency

基　　金：国家自然科学基金项目"云质岩致密油储层微米-纳米孔喉网络体系及其流体耦合流动机理与流动下限"(41372145)

摘　　要：为揭示页岩气储层的形成机制,明确时空展布规律,指导页岩气的勘探部署,通过岩心观察和重力流理论分析,对湖南保靖地区下志留统重力流沉积特征及沉积模式进行研究。结果表明,湖南保靖地区下志留统主要发育浊流、碎屑流和液化流3种重力流沉积类型。其中,浊流发育不完整的鲍马序列浊积岩,下部以多期次单段式或两段式浊积岩叠加的进积型地层组合为主,上部以多期次三段式浊积岩叠加的加积型地层组合为主;碎屑流以块状细砂岩为主;液化流以厚层的泥质粉砂岩或粉砂质泥岩为主,发育变形层理。从下志留统龙马溪组沉积时期到马脚冲组沉积时期,湖南保靖地区断续发育海底扇、远岸水下扇和滑移-滑塌扇3种沉积模式。浊流主要发育海底扇扇端亚相浊积砂、扇端泥微相,扇中亚相网状水道、水道侧缘、前缘席状砂微相以及远岸水下扇扇中亚相水道侧缘、前缘席状砂微相,碎屑流发育远岸水下扇扇中亚相辫状水道微相,液化流发育滑移-滑塌扇扇中亚相滑移-滑塌水道、水道间湾微相。Based on cores data and gravity flow theory,the sedimentary characteristics and models of early Silurian gravity flow deposits were systematically analyzed in Baojing area of Hunan Province,which intends to reveal formation mechanism of shale gas reservoir and determine its temporal and spatial distribution and thus guide the shale gas exploration. The results show that there are three types of gravity flow developed during the early Silurian in Baojing area of Hunan Province,including turbidity currents,debris flow and liquid flow. Among them,the turbidite current results in incomplete Bouma sequence,which is composed mainly of progradational strata formed by superposition of multiple single-section or twosection turbidite at the bottom and aggradational strata formed by superposition of multiple three-section turbidite at the top.Massive fine sandstone is the dominant lithology developed from debris flow. Thick layer of argillaceous siltstone and silty mudstone are the dominant lithology developed from liquid flow,in which deformation bedding develops. From the deposition of Longmaxi Formation to the deposition of Majiaochong Formation in the early Silurian,submarine fan,off-shore underwater fan and slump-slip fan developed intermittently in Baojing area of Hunan Province. Turbidity current mainly results in fan-end turbidite sand and fan-end mud of submarine fan,braided channel,channel edge and front sheet sand at mid submarine fan and channel edge and front sheet sand at off-shore subaqueous fan. The debris flow results in braided channel at off-shore underwater fan. The liquid flow results in slump-slip channel at mid fan and bay at inter channels.

关 键 词：重力流 浊流 液化流 碎屑流 下志留统 湖南保靖地区 

分 类 号：TE112.2[石油与天然气工程—油气勘探]