摘要
针对鄂尔多斯盆地三叠系延长组地层对比中出现的井-震矛盾,以层序地层学理论为指导,通过深入分析过往地层划分方案、最新三维地震区井-震资料及油藏剖面等,系统搭建延长组前积型层序地层格架,揭示出新的坳陷湖盆沉积机制,并成功应用于庆城油田勘探开发实践。研究表明:(1)延长组地震前积层、凝灰岩标志层和洪泛面凝缩层3层一致且具有等时意义,以洪泛面标志层为基准,重构了盆地延长组中上部前积型层序地层结构,划分为CF1—CF7等7套斜坡地层单元;(2)前积现象主要分布在半深湖和深湖区,沉积中心并非总是地层最厚,湖盆经历了“震荡湖退-进积充填-多期叠加”的演化过程;(3)庆城油田实例分析表明,主力油层为“同相异期”的重力流砂岩复合体,以前积型层序地层结构为指导,实现了水平井油层钻遇率保持在82%以上。前积型层序地层格架及地质认识更契合大型陆相坳陷湖盆的沉积充填规律和实际钻探结果,为延长组后期精细勘探开发提供了理论技术依据,并有望为类似陆相湖盆研究和生产实践提供参考借鉴。
To address the discrepancies between well and seismic data in stratigraphic correlation of the Triassic Yanchang Formation in the Ordos Basin,NW China,traditional stratigraphic classification schemes,the latest 3D seismic and drilling data,and reservoir sections are thoroughly investigated.Guided by the theory of sequence stratigraphy,the progradational sequence stratigraphic framework of the Yanchang Formation is systematically constructed to elucidate new depositional mechanisms in the depressed lacustrine basin,and it has been successfully applied to the exploration and development practices in the Qingcheng Oilfield.Key findings are obtained in three aspects.First,the seismic progradational reflections,marker tuff beds,and condensed sections of flooding surfaces in the Yanchang Formation are consistent and isochronous.Using flooding surface markers as a reference,a progradational sequence stratigraphic architecture is reconstructed for the middle-upper part of Yanchang Formation,and divided into seven clinoform units(CF1–CF7).Second,progradation predominantly occurs in semi-deep to deep lake environments,with the depositional center not always coinciding with the thickest strata.The lacustrine basin underwent an evolution of“oscillatory regression–progradational infilling-multi-phase superimposition”.Third,the case study of Qingcheng Oilfield reveals that the major pay zones consist of“isochronous but heterochronous”gravity-flow sandstone complexes.Guided by the progradational sequence stratigraphic architecture,horizontal well oil-layer penetration rates remain above 82%.The progradational sequence stratigraphic architecture and associated geological insights are more consistent with the sedimentary infilling mechanisms of large-scale continental depressed lacustrine basins and actual drilling results.The research results provide crucial theoretical and technical support for subsequent refined exploration and development of the Yanchang Formation,and are expected to offer a reference for research and production practice in similar continental lacustrine basins.
作者
惠潇
侯云超
屈童
张杰
杨智
HUI Xiao;HOU Yunchao;QU Tong;ZHANG Jie;YANG Zhi(Research Institute of Exploration and Development,PetroChina Changqing Oilfield Company,Xi’an 710018,China;National Engineering Laboratory for Exploration and Development of Low Permeability Oil&Gas Fields,Xi’an 710018,China;PetroChina Research Institute of Petroleum Exploration&Development,Beijing 100083,China)
出处
《石油勘探与开发》
北大核心
2025年第5期1028-1040,共13页
Petroleum Exploration and Development
基金
国家科技重大专项“大型岩性油气藏形成主控因素与有利区带评价”(2017ZX05001)
中国石油天然气集团有限公司科技项目“长庆油田探区“十四五”油气资源评价”(2023YQX20111)。
关键词
前积型地层结构
斜坡沉积
洪泛面
陆相坳陷湖盆
鄂尔多斯盆地
三叠系
延长组
progradational sequence stratigraphic architecture
clinoform
flooding surface
continental depression lacustrine basin
Ordos Basin
Triassic
Yanchang Formation
