多辐射场源地空瞬变电磁一维反演方法研究

A study of 1D inversion of multi-source ground-airborne transient electromagnetic method

地空瞬变电磁法融合了地面与航空瞬变电磁的方法原理与观测模式,将发射源置于地表,并利用航空器在空中接收响应信号。因此,地空瞬变电磁法同时具有地面装置大测深、高信噪的优势以及航空装置中采集高效的优势。先有研究偏重于单一辐射源,忽略了多辐射场源在勘探深度与信噪比上的优势。因此需要研究适用于多辐射场源地空装置的数据解释方法。在解决多辐射场源地空瞬变电磁正演问题之后,以Occam反演理论为基础,对多辐射场源地空瞬变电磁一维反演进行研究。首先要构建目标函数,本文通过引入拉格朗日乘子,将数据拟合差及模型粗糙度组合起来进而构建目标函数;其次解决灵敏度矩阵的构建问题。模型计算结果表明本文多辐射场源地空瞬变电磁法一维反演算法的有效性,可为三维反演与精细解释提供良好的基础。通过对典型模型的反演计算,从其理论模型及反演结果的对比可以看出,Occam反演方法可以应用到多辐射场源地空瞬变电磁系统中,为多辐射场源地空瞬变电磁解释增加了新途径。

The ground-airborne transient electromagnetic method combines the principle and observation mode of ground and air transient electromagnetic survey, places the emission source on the surface, and uses the aircraft to receive the response signal in the air. Therefore, the ground-airborne transient electromagnetic method has the advantages of large sounding depth of the ground device, high signal-to-noise ratio and high efficiency of aviation equipment acquisition. Previous studies have focused on a single source of radiation, ignoring the advantages of multi-radiation field sources in exploration depth and signal-to-noise ratio. Therefore, it is necessary to study the data interpretation method applicable to the ground device of the multi-radiation field source. After solving the problem of the ground-airborne transient electromagnetic forward modeling and on the basis of the principle of Occam inversion, the authors studied one-dimensional inversion of multi-source ground-airborne transient electromagnetic survey. First of all, the important problem is the construction of objective function, and the objective function is constituted by the misfit and model roughness by introducing the Lagrange multiplier. Secondly, the problem of the construction of the sensitivity matrix is solved. The model calculation results show 1D Inversion of Multi-source Ground-airborne Transient Electromagnetic Method is effective, which can provide a good foundation and fine interpretation for three-dimensional inversion and fine interpretation. Through the inversion calculation of the typical model, it can be seen from the comparative study of its theoretical model and inversion results that the Occam inversion method can be applied to the Multi-source Ground-airborne Transient Electromagnetic Method, and adds a new approach to the interpretation of the Multi-source Ground-airborne TEM.