基于LBFGS的ZTEM三维带地形并行反演

Parallel Inversion of ZTEM 3D Terrain based on LBFGS

Z轴倾子电磁法(ZTEM)结合了航空测量效率高和天然场源勘探深度大的优点,弥补了地面MT采集数据所带来的人工成本高、耗时长以及复杂地形测量困难等缺点,通过空中航测的垂直磁场分量和地面预设基站测量的水平磁场分量建立航空倾子数据,可快速、高效获得地下电导体三维构造信息。为了进一步提高ZTEM面向复杂工程勘查的反演能力,该文在有限差分法正演和有限内存拟牛顿法(LBFGS)反演的基础上,加入MPI并行算法,对带地形的三维ZTEM异常响应进行了研究,并开发了ZTEM带地形三维反演程序。通过对带地形与平地形下低阻异常体反演算例分析,证实了LBFGS反演算法可以较好地获得地下目标体的真实地电模型。

The Z-axis tilter electromagnetic method(ZTEM)combines the advantages of high efficiency of aerial survey and large depth of natural field source exploration,and makes up for the shortcomings of high labor cost,long time-consuming and difficult survey of complex terrain caused by the ground MT acquisition data.The airborne tilter data is established through the vertical magnetic field component of aerial survey and the horizontal magnetic field component measured by the ground preset base station,and the three-dimensional structure information of underground electric conductor can be obtained quickly and efficiently.In order to further improve the inversion ability of ZTEM for complex engineering exploration,this paper adds the MPI parallel algorithm on the basis of finite difference forward modeling and finite memory quasi Newton method(LBFGS)inversion to study the three-dimensional ZTEM anomaly response with terrain,and develops the three-dimensional inversion program of ZTEM with terrain.Through the analysis of inversion examples of low resistivity anomaly under terrain and flat terrain,it proves that the LBFGS inversion algorithm can better obtain the real geoelectric model of underground target.