基于电阻率测井的冻土区水合物储层AMT响应特征研究  

Audio magnetotelluric response characteristics of gas hydrate reservoir in the permafrost based on resistivity logging

作　　者：肖昆 邹长春[2] 卢振权 杨亚新[1] 李红星[1] 段忠义 XIAO Kun;ZOU Changchun;LU Zhenquan;YANG Yaxin;LI Hongxing;DUAN Zhongyi(State Key Laboratory of Nuclear Resources and Environment,(East China University of Technology),Nanchang,Jiangxi 330013,China;Key Laboratory of Geo-detection,Ministry of Education,China University of Geosciences(Beijing),Beijing 100083,China;Oil&Gas Survey,China Geological Survey,Beijing 100029,China)

机构地区：[1]东华理工大学核资源与环境国家重点实验室,江西南昌330013 [2]中国地质大学(北京)地下信息探测技术与仪器教育部重点实验室,北京100083 [3]中国地质调查局油气资源调查中心,北京100029

出　　处：《地质学报》2023年第12期4179-4197,共19页Acta Geologica Sinica

基　　金：江西省主要学科学术和技术带头人培养计划项目(编号20204BCJ23027);国家自然科学基金项目(编号41804116);核资源与环境国家重点实验室联合创新基金项目(编号2022NRE-LH-18);江西省自然科学基金项目(编号20232BAB203072)联合资助的成果。

摘　　要：音频大地电磁测深(AMT)是以岩石的电性差异为基础来研究地层电性结构的有效探测方法。冻土区水合物具有显著的高阻特征,与围岩存在电性差异,AMT方法可用于冻土区水合物勘探评价。基于祁连山冻土区水合物储层的实际赋存地质特征,结合电阻率测井建立水合物储层的地电模型,采用有限单元法和非线性共轭梯度法数值模拟了AMT方法探测水合物储层的适用范围和最佳采集参数设置方案。当水合物储层孔隙度小于5%、水合物饱和度大于70%、赋存规模小于50 m、埋深超过500 m时,AMT方法难以识别与圈定水合物储层;在水合物可能赋存区域,效果最佳的采集参数为3倍区域宽度的测线长度、11个测点数、4个高频段(100~1000 Hz)的频点数。研究结果可为祁连山冻土区水合物电法勘探提供理论依据和技术支撑。Audio magnetotelluric(AMT)is an effective exploration method to study the electrical structure of strata based on the electrical differences of rocks.The gas hydrate in the permafrost has the characteristic of high resistivity,which is different from the surrounding rock electrically.The AMT method can be used for the exploration and evaluation of gas hydrate in the permafrost.Based on the actual geological characteristics of gas hydrate reservoir in the Qilian Mountain permafrost,the geoelectric model of gas hydrate reservoir is established by combining with resistivity logging.The application range of AMT method for gas hydrate reservoir detection and the optimal acquisition parameter setting scheme were simulated by using finite element method and nonlinear conjugate gradient method.When porosity of gas hydrate reservoir is less than 5%,gas hydrate saturation is greater than 70%,occurrence scale is less than 50 m,or burial depth is greater than 500 m,AMT technique cannot identify and delineate the favorable gas hydrate reservoir.Survey line should be more than twice the length of probable occurrence scale,while tripling the length will make the best result.The number of stations should be no less than 6,and 11 stations are optimal.At the high frequency section(10~1000 Hz),there should be no less than 3 frequency points,4 being the best number.The research results could provide important reference for gas hydrate reservoir electrical prospecting in the Qilian Mountain permafrost.

关 键 词：祁连山冻土区 水合物 电阻率测井 音频大地电磁测深 响应特征 

分 类 号：P618.13[天文地球—矿床学] P631.81[天文地球—地质学]