磁偶极子构造法球形磁性矿体磁异常正演

球形磁性地质体是地质勘探中广泛遇到的基本地质体之一,选择合适的磁异常分析方法对其磁场进行准确正演计算具有重要的意义.为了准确快速地求解球形磁性地质体磁场特征,本文提出了一种基于磁偶极子构造原理求解球形磁性地质体磁场的数值计算方法,对球形磁性地质体按半径由小增大进行多层单元分割,再对每层单元进行块单元分割,将每个块单元视为"磁偶极子",利用基本磁偶极子公式计算了所有块单元在探测平面(线)的磁场大小,同时分析了球体磁场的剖面特征,并将数值解与解析解结果进行了对比和误差分析,最后建立双球组合模型结合Comsol多物理场仿真工具对其仿真对比,验证了磁偶极子构造法求解球体磁场的准确性.研究结果表明:数值解法结果与解析解结果磁异常波动趋势完全一致;不同测点处绝对误差有所差别,但磁异常值均在1 nT以下.本文提出的数值解法无需复杂的数学推导,计算结果稳定可靠.

Magnetic dipole reconstruction method for forward modeling of magnetic anomaly of spherical magnetic body

The spherical magnetic geological body is one of the basic geological bodies widely encountered in geological exploration.When the underground magnetic ore body is close to the earth's surface,the magnetic target is directly regarded as a magnetic dipole to calculate the magnetic field strength by the formula for calculating the pole magnetic field will cause a large error.Therefore,according to the actual needs of the exploration environment,it is especially important to choose the magnetic field forward mode.With the development of society,computers have been widely used in all walks of life.Due to their powerful data calculation and processing functions have made it very useful for researchers to use the“numerous”micro-element superposition to find the physical field of complex geometry.This paper is also based on the research ideas,proposed a MATLAB-based spherical magnetic body magnetic field calculation method.So in order to solve the ball accurately and rapidly magnetic magnetic field geological characteristics,this paper proposes a solution on the basis of the principle of magnetic dipole structure of spherical magnetic geologic body magnetic field numerical calculation method,the spherical magnetic geologic body multilayer unit division,according to radius increases by a small block units on each floor unit division,each block unit as a magnetic dipole,the basic formula of magnetic dipole is used to calculate the unit all block in the detection plane(line)the size of the magnetic field,at the same time analyzed the sphere profile characteristics of magnetic field,and compares the result with numerical solution and analytic solution and error analysis,Finally,the two-sphere model combined with Comsol multi-physical field simulation tool is used to verify the accuracy of the magnetic dipole construction method to solve the magnetic field of the sphere.The results show that the numerical results are consistent with the analytical results.The absolute errors at different measuring points are different,but the magnetic outliers are all below 1 nT.The numerical method proposed in this paper does not need complex mathematical derivation and the results are stable and reliable.