同时考虑退磁和剩磁的有限体积法正演模拟  

Forward modeling of magnetic data using the finite volume method with a simultaneous consideration of demagnetization and remanence

作　　者：欧洋[1,2] 冯杰 赵勇[3] 贾定宇 高文利 OU Yang;FENG Jie;ZHAO Yong;JIA DingYu;GAO WenLi(Institute of Geophysical and Geochemical Exploration,Chinese Academy of Geological Science,Hebei Langfang 065000,China;Laboratory of Geophysical EM Probing Technologies,Ministry of Land and Resources,Hebei Langfang 065000,China;The Third Institution of Qinghai Geological Mineral Prospecting,Xining 810000,China)

机构地区：[1]中国地质科学院地球物理地球化学勘查研究所,廊坊065000 [2]国土资源部地球物理电磁法探测技术重点实验室,廊坊065000 [3]青海省第三地质矿产勘查院,西宁810000

出　　处：《地球物理学报》2018年第11期4635-4646,共12页Chinese Journal of Geophysics

基　　金：国家高技术研究发展计划(2014AA06A608);物化探研究所基本科研业务费专项资金项目(AS2014J01;AS2016J06;AS2016J07)资助

摘　　要：为分析同时考虑退磁和剩磁对磁测数据解释的影响,探讨了利用有限体积法求静磁场数值解的方法.从静磁场中的麦克斯韦方程出发,导出了有限体积法控制方程的离散表达式,对边界条件近似处理后求解方程组得到磁异常.通过与退磁改正计算结果对比,验证了方法的正确性,并分析得到忽略剩磁的相对误差与科尼斯布格比(Q)相关;利用有限体积法计算长方体模型在无地磁场情况下的磁异常和内部磁化强度,从数值模拟上说明剩磁也需要进行退磁改正,并表明退磁作用对剩磁的影响不仅与磁化率相关,而且与剩磁的方向和磁性体的形态相关;组合模型的计算结果对比表明,退磁作用对剩磁的影响还会因为临近强磁性体的作用发生改变.在青海灶火河西工区的应用说明,开展同时考虑退磁和剩磁的解释方法对准确识别强磁性岩体具有实用价值.To analyze the impact of the simultaneous consideration of demagnetization and remanence on the interpretation of magnetic data,we discuss application of the finite volume method to the numerical solution of the magnetostatic field.The discrete expressions of governing equation is derived from Maxwell′s equations.The magnetic anomalies are calculated after the approximate treatment on the boundary conditions.Comparison with the results of the demagnetization correction has confirmed this method′s correctness,and the analysis has shown that the relative error of neglecting remanence is related to the Koenigsberger ratio(Q).This method is used to calculate magnetic anomalies and internal magnetization distributions of a cuboid when no geomagnetic field is present,demonstrating that remanence also requires demagnetization correction.And it shows that the impact of demagnetization on remanence is related to not only susceptibility but also the direction of remanence and the shape of the magnetic body.The comparison of the combined model shows that the adjacent,strong magnetic body can also change the effect of demagnetization on remanence.Finally,the application of this method to the Zaohuohexi area of Qinghai indicates that the interpretation with a simultaneous consideration of demagnetization and remanence is of great significance for accurately identifying strong magnetic rock bodies.

关 键 词：退磁 剩磁 正演模拟 退磁改正 有限体积法 灶火河西 

分 类 号：P631[天文地球—地质矿产勘探]