西藏羊八井地热田SOTEM探测及热储结构分析  

SOTEM exploration and reservoir structure analysis of Yangbajain geothermal field,Xizang

作　　者：陈卫营[1,2] 薛国强 赵平[2,3] 任旺奇 何一鸣 吕鹏飞[1,2] 雷康信 赵炀 CHEN WeiYing;XUE GuoQiang;ZHAO Ping;REN WangQi;HE YiMing;LÜPengFei;LEI KangXin;ZHAO Yang(Key Laboratory of Mineral Resources,Institute of Geology and Geophysics,Chinese Academy of Sciences,Beijing 100029,China;University of Chinese Academy of Sciences,Beijing 100049,China;State Key Laboratory of Tibetan Plateau Earth System,Resources and Environment(TPESRE),Institute of Tibetan Plateau Research,Chinese Academy of Sciences,Beijing 100101,China;School of Geosciences and Info-Physics,Central South University,Changsha 410083,China)

机构地区：[1]中国科学院矿产资源研究重点实验室,中国科学院地质与地球物理研究所,北京100029 [2]中国科学院大学地球与行星科学学院,北京100049 [3]青藏高原地球系统与资源环境全国重点实验室,中国科学院青藏高原研究所,北京100101 [4]中南大学地球科学与信息物理学院,长沙410083

出　　处：《地球物理学报》2023年第11期4805-4816,共12页Chinese Journal of Geophysics

基　　金：第二次青藏高原综合科学考察研究项目(2019QZKK0804);国家自然科学基金项目(U21A2015,42274192,42010306);中国科学院地质与地球物理研究所重点部署项目(IGGCAS-201901)共同资助。

摘　　要：西藏羊八井地热田是世界上著名的高温地热田,历经四十多年的开发利用,浅部地热资源日趋萎缩,亟需开发深部高温地热资源来维持地热发电或新增装机容量.深刻了解断裂分布特征、地热流体的升流通道,对于开发深部高温地热资源具有十分重要的意义.我们在羊八井地热田实施了6条电性源短偏移距瞬变电磁法(SOTEM)探测剖面,通过反演获得了2 km深度范围内地层的电性结构.结合现有的构造地质、地球物理、地球化学、钻孔测温等资料,取得了如下新认识:(1)确认F14断裂是地热流体从地热田北区向南区运移的主通道;(2)深部地热流体的上升通道出现在北区硫磺沟,中尼公路附近下伏渗透性较差的基岩阻挡着地热流体在深处从北区向南区的侧向流动;(3)南区深处存在一个富水区,汇聚着来自唐山的大气降水和冰雪融水,与正在开采的浅层热储水力联系较弱;(4)在南区实施尾水回灌,难以实现维持热储压力、延长地热田开采寿命的目的.The Yangbajain geothermal field in Xizang is a worldwide famous high-temperature geothermal field,and has been explored and exploited for more than four decades.Unfortunately,the shallow geothermal resources are gradually exhausted,thus it's urgent to explore deep high-temperature geothermal resources for geothermal power generation or increasing installed capacity.It's well known that comprehensively understanding the distribution of faults and the upwelling channels of geothermal fluids are of great value for exploiting the deep high-temperature geothermal resources.Therefore,we have carried out the short-offset transient electromagnetic(SOTEM)explorations with six survey lines in Yangbajain geothermal field,and further obtained the electrical structures within the depth of 2 km by analyzing the inversion profiles.Combined with the currently existing cognition of the structural geology,geophysics,geochemistry and drillings,we got some brand-new understandings as follows.Firstly,fault F14 is the main channel for geothermal fluid migration from the north to the south of the geothermal field.Secondly,the upwelling channel of deep geothermal fluid appears in the sulfur ditch in the north while the underlying basement with poor permeability near the China-Nepal Highway blocks the lateral flow of the deep geothermal fluid from the north to the south.Thirdly,there is a low-resistance in the deep part of the south area,gathering atmospheric precipitation and ice snow melt water from Tang Mountain,and has weak connection with the existing shallow thermal reservoir.Finally,it's difficult to effectively take measures to maintain the thermal storage pressure and extend the exploitation period of geothermal field in the south of the geothermal field.

关 键 词：羊八井地热田 SOTEM 电性结构 运移通道 热储结构 

分 类 号：P631[天文地球—地质矿产勘探]