Research On High-precision Gravity And Magnetic Data Processing Method With Multi-source Equivalent Layer

The conversion of gravity and magnetic data is to better reflect the characteristics of field sources and provide accurate basic data for inversion,so the accuracy of conversion results restricts the accuracy of inversion.Equivalent source is a common and high precision conversion method in gravity and magnetic data processing.It establishes the equivalent model underground and calculates the physical property distribution of the model,so as to realize the data conversion.Traditionally,a single layer model is established underground to realize the calculation,but it is difficult to retain the abnormal variation characteristics of the source body at different depths.In order to effectively improve the data conversion accuracy,a multi-source equivalent layer conversion method based on the spectral characteristics of gravity and magnetic data is proposed.The equivalent layer of multi-layer prism is established by the approximate linear correspondence between the slope of radial mean logarithmic power spectrum of potential field data and the buried depth of geological body.Equivalent thickness by the separation of the layers to determine the abnormal amplitude ratio,through the corresponding equivalent layer separation of exceptions to obtain the property distribution,without depth weighting coefficient under the condition of the transition of magnetic data,can effectively preserve the abnormal change characteristics of different depth of field source,thus get higher accuracy of the conversion results.The model experiment shows that the multi-source equivalent layer method based on the spectral characteristics of the data can achieve more accurate data conversion,especially the upward continuation of a large height can still get accurate results,and can better reduce the interference of noise.In view of potential field data in different measurement ranges,spectral multisource equivalent layer is selected for data analysis and equivalent model establishment,so as to improve the utilization rate of data in different periods and different sampling methods,so as to carry out high-precision fusion and transformation,and provide more accurate data for inversion.Under the condition of the same observation range and partial coincidence observation range,the fusion method of the space position field model data is compared with the transformation method of multiple original anomalies and their gradients at multiple observation heights,and the multi-source equivalent layer of spectrum has a good fusion transformation effect.It is applied to the ground magnetic survey and aeromagnetic survey results in a certain area of Inner Mongolia to carry out the data fusion of aviation at a certain height and calculate the derivative transformation results at three observation positions.The fusion transformation results have a good correspondence with the geological structure.In order to give full play to the data conversion effect of the multi-source equivalent layer method based on spectrum analysis,the multi-source equivalent layer method was applied to the magnetic data conversion in Huangpu District,Shanghai.The anomaly calculation in the upper half space was realized by this method,and the location information of underground field sources was obtained by using the ratio DEXP method.Using singular value decomposition of a number of different heights and magnetic data correlation analysis,put forward the three dimensional joint gradient Euler deconvolution method,through the model test of the method have good stability and resistance to noise.The proposed method is applied to the fusion and transformation data obtained by spectral multi-source equivalent layer method in a certain area of Inner Mongolia,and the approximate range of geological body and the source location of geological body information can be given quickly and accurately,which has good practical application effect.