鄂尔多斯盆地七里村油田长6和长7重力流沉积的发现及其意义

Discovery and significance of gravity flow deposits of Chang 6 and Chang 7 in Qilicun Oilfield,Ordos Basin

基于岩心观察、粒度分析和测井相分析等,在鄂尔多斯盆地东南部七里村油田三叠系延长组长6段和长7段发现了重力流沉积。该区重力流沉积类型主要有滑塌沉积、砂质碎屑流沉积和浊流沉积。研究区重力流的形成过程可分为5个阶段:三角洲前缘沉积阶段、滑动阶段、滑塌阶段、砂质碎屑流沉积阶段和浊流沉积阶段。受湖盆底形、触发机制、古水深等因素共同影响,重力流发育湖底扇模式,砂质碎屑流主要是舌状体;浊流主要是朵叶体。基于物源、坡度和触发条件等的分析,建立研究区重力流沉积演化模式和重力流沉积模式图。

Based on core observation,grain size analysis,and logging facies analysis,gravity flow deposits were discovered in the 6th and the 7th member of the Triassic Yanchang Formation of the Qilicun Oilfield in the southeastern Ordos Basin.This area's main types of gravity flow deposits are slump deposits,sandy clastic flow deposits,and turbidity flow deposits.The formation process of gravity flow in the study area can be divided into five stages:delta front sedimentation stage,sliding stage,slump stage,sandy clastic flow deposition stage,and turbidity current deposition stage.Under the joint influence of the bottom shape of the lake basin,triggering mechanism,and palaeodepth,the gravity flow develops into a lake bottom fan model,and the sandy debris flow is mainly a tongue.Based on the analysis of provenance,slope,and trigger conditions,the gravity flow depositional evolution model and gravity flow sedimentary model map are established in the study area.