鄂尔多斯盆地中元古界长城系地质特征与勘探前景  

Geological characteristics and exploration prospects of the Mesoproterozoic Changcheng System in Ordos Basin

作　　者：刘刚[1,2] 杨文敬 井向辉[1,2] 白海峰[1,2] 时保宏[4] 孙亚平[5] 任军峰 潘星[1,2] 张建伍[1,2] 魏嘉怡 Liu Gang;Yang Wenjing;Jing Xianghui;Bai Haifeng;Shi Baohong;Sun Yaping;Ren Junfeng;Pan Xing;Zhang Jianwu;Wei Jiayi(Research Institute of Exploration&Development,PetroChina Changqing Oilfield Company;National Engineering Laboratory for Exploration and Development of Low Permeability Oil&Gas Fields;Exploration Department,PetroChina Changqing Oilfield Company;Xi’an Shiyou University;Changqing Supervision Company,CNPC Chuanqing Drilling Engineering Co.,Ltd.)

机构地区：[1]中国石油长庆油田公司勘探开发研究院,710018 [2]低渗透油气田勘探开发国家工程实验室 [3]中国石油长庆油田公司勘探事业部 [4]西安石油大学 [5]川庆钻探有限公司长庆监督公司

出　　处：《中国石油勘探》2024年第5期44-60,共17页China Petroleum Exploration

基　　金：中国石油长庆油田公司科研项目“鄂尔多斯盆地中元古界长城系沉积特征与勘探潜力研究”(2023DJ0104);“鄂尔多斯盆地风险勘探领域和目标研究、工程技术攻关及现场试验”(2023YQX10105)。

摘　　要：中元古代长城系是鄂尔多斯盆地第一套沉积盖层,分布范围广,研究与勘探程度较低。利用野外露头、风险探井PT1井等钻井成果及三维地震等资料,开展了长城系地层对比与展布、沉积和烃源岩特征等系统分析。鄂尔多斯盆地长城系自下而上主要发育熊耳群、白草坪组、北大尖组、崔庄组和洛峪口组5段层组;在不同裂陷槽具有不同的展布特征,在晋陕裂陷槽,长城系发育熊耳群、白草坪组、北大尖组、崔庄组和洛峪口组;定边裂陷槽发育熊耳群、白草坪组和北大尖组;贺兰裂陷槽仅发育北大尖组。长城系以半深海—浅海—滨岸—三角洲沉积体系为主,期间发育潮坪沉积。熊耳裂谷及盆地次级裂陷槽的多口探井均在崔庄组发现有效的烃源岩,有机碳含量最高为1.52%,R_(o)平均为2.32%,具有规模生烃的成藏潜力;盆地热演化模拟表明,崔庄组烃源岩于二叠世中期R_(o)达到0.5%时进入成熟阶段,早白垩世晚期R_(o)达到2.0%时进入生干气阶段。综合研究认为,鄂尔多斯盆地长城系烃源岩与储层源储配置良好,可以形成自生自储的天然气藏,优选定边裂陷槽、晋陕裂陷槽两个勘探目标,为盆地深层天然气“向源”勘探提供了方向。The Mesoproterozoic Changcheng System was the first set of sedimentary cap rocks in Ordos Basin,with a wide distribution area but a relatively low level of research and exploration.By using field outcrops,drilling results of risk exploration well PT1,and 3D seismic data,a systematic study is conducted on stratigraphic correlation and distribution,sedimentary facies,and source rock characteristics in the Changcheng System.In Ordos Basin,five sets of formations were developed in Changcheng System from bottom to top,including Xiong’er Group,Baicaoping Formation,Beidajian Formation,Cuizhuang Formation,and Luoyukou Formation.The stratigraphic distribution characteristics vary in various rift troughs.In Jinshan rift trough,the five sets of formations were developed completely.In Dingbian rift trough,three sets of formations were developed,including Xiong’er Group,Baicaoping Formation and Beidajian Formation.While only Beidajian Formation was developed in Helan rift trough.The bathyal-shallow marine-coastal-delta sedimentary system was dominant in Changcheng System,intercalated with tidal flat deposits.Effective source rock in Cuizhuang Formation was encountered in Xiong’er rift and several exploration wells in the secondary rift troughs,with the highest organic carbon content of 1.52% and average R_(o) of 2.32%,showing potential of large-scale hydrocarbon generation.The basin thermal evolution simulation shows that Cuizhuang Formation source rock entered the mature stage in the Middle Permian with R_(o) value of 0.5%,and entered dry gas generation stage in the late stage of the Early Cretaceous with R_(o) of 2.0%.The comprehensive study shows that the configuration between source rock and reservoir in Changcheng System was good in Ordos Basin,forming self-generation and self-storage type natural gas reservoirs.Furthermore,two exploration targets are optimally selected in Dingbian rift trough and Jinshan rift trough,providing direction for gas exploration“towards source rock”in deep formations in the basin.

关 键 词：鄂尔多斯盆地 中元古界 长城系 崔庄组 沉积相 烃源岩 勘探前景 

分 类 号：TE122.11[石油与天然气工程—油气勘探]