鄂尔多斯盆地西南庆城地区延长组前积斜坡生长及其控砂规律  

Clinoform Growth and Its Controls on the Distribution of Sandstone in the Yanchang Formation,Qingcheng Area,Southwestern Ordos Basin

作　　者：夏勇 惠潇[2] 赵俊峰[1] 侯云超 李慧琼[1,3] 白金莉 刘永涛 XIA Yong;HUI Xiao;ZHAO JunFeng;HOU YunChao;LI HuiQiong;BAI JinLi;LIU YongTao(State Key Laboratory of Continental Dynamics/Department of Geology,Northwest University,Xi'an 710069,China;Research Institute of Exploration and Development,Changqing Oilfield Company,PetroChina,Xi'an 710018,China;Research Institute of Shaanxi Yanchang Petroleum(Group)Co.,Ltd.,Xi'an 710065,China;Changqing Branch of Geophysical Research Institute,BGP,PetroChina,Xi'an 710021,China)

机构地区：[1]西北大学大陆动力学国家重点实验室/地质学系,西安710069 [2]中国石油长庆油田分公司勘探开发研究院,西安710018 [3]陕西延长石油(集团)有限责任公司研究院,西安710065 [4]中国石油东方地球物理公司研究院长庆分院,西安710021

出　　处：《沉积学报》2025年第1期273-287,共15页Acta Sedimentologica Sinica

基　　金：国家自然科学基金项目(42172123,42230815)。

摘　　要：【目的】前积斜坡在湖泊或海洋环境中均可出现,其生长方式能够反映物源、湖平面及沉积物输送和分散样式的变化。鄂尔多斯盆地西南部最新三维地震资料显示,延长组中上部存在较典型的前积斜坡生长现象。这一发现改变了以往延长组“千层饼式”沉积分层的传统认识,也为分析三角洲—深湖区砂体分布规律及储层预测提供了新思路。【方法】以斜坡生长理论为指导,基于三维地震和钻井资料,将鄂尔多斯盆地西南部庆城地区延长组长7—长1油层组依次划分为F1~F6共6期前积斜坡体。【结果与结论】定量表征了发育较完整的F1~F4斜坡体特征,识别出平坦型(0°~0.5°)和低角度上升型(0.5°~1.0°)两种坡折迁移轨迹。F1沉积期,物源供应弱,湖盆规模最大,形成加积型斜坡,砂体主要发育于顶积层。F2~F3沉积期,物源供应增强,湖盆收缩,形成进积型斜坡,具有平坦型迁移轨迹,砂体主要分布在深湖区。F4沉积期,形成加积—进积混合型斜坡,具有低角度上升型迁移轨迹,顶积层及深湖区均富砂。物源供给与湖平面变化是研究区斜坡生长及砂体分布的主控因素。[Objective]Clinoform growth is found in lacustrine or marine basins,and its growth mode reveals the changes of sediment supply,lake level,and deep-water sand delivery pattern.The typical clinoform growth styles are identified in the middle-upper Yanchang Formation based on newly obtained three-dimensional(3D)seismic data in the southwestern Ordos Basin.This discovery has changed the traditional understanding of the“flat-filling”deposi-tion of the Yanchang Formation,provided a new idea for analyzing the distribution of sandstone and reservoir predic-tion from delta to deep-water area.[Methods]Based on the 3D seismic and drilling data from the Qingcheng area in the southwestern Ordos Basin,the middle-upper Yanchang Formation can be divided into six clinothems named F1-F6 respectively,guided by the clinoform growth theory.The characteristics of clinothems F1-F4 were described quan-titatively,with relatively complete slope form.[Results]First,the results show that the four clinothems have similar morphological characteristics based on the representative seismic profiles in the study area.All four clinothems have lenticular external morphology and S-shaped internal reflection structure.Second,the sedimentary time span of one clinothem is approximately 4 to 6 million years.Third,clinothems F1-F4 can be quantitatively divided into two types,“thick-topset and thin-foreset”and“thin-topset and thick-foreset”based on the strata thickness.Clinothem F1 belongs to the former type,while the other three clinothems belong to the latter type.Fourth,two types of shoreline trajectories were identified,including flat of 0°-0.5°and slightly rising of 0.5°-1.0°.The trajectory angle of F2 is 0.366°-0.489°and the angle of F3 is 0.256°-0.275°.While the trajectory angle of F4 is 0.475°-0.673°,which has a slight increase compared with the previous period of F2 and F3.Moreover,the shoreline trajectories of F2 and F3 are flat,while the shoreline trajectories of F4 are slightly rising.[Conclusions]The lacustrine basin rea

关 键 词：前积斜坡体 滨线迁移轨迹 砂体分布样式 延长组 庆城地区 鄂尔多斯盆地 

分 类 号：P618.13[天文地球—矿床学]