Study On Imaging Of Mine Rich Water Area Based On RTM

The algorithm of reverse time migration imaging is the most intuitive method in electromagnetic detection.Due to the complex underground environment and serious electromagnetic interference,the resolution of imaging is directly affected.Therefore,it is of great significance to carry out imaging denoising study and improve inverse-time migration imaging resolution for electromagnetic detection.Aiming at the problems of low-frequency noise interference in inverse time migration imaging,Laplace filtering is used to filter out low-frequency noise generated by reverse time migration imaging to improve imaging resolution.In this thesis,the finite-difference time-domain algorithm is introduced into the process of inverse time migration imaging.The determination of numerical stability conditions,selection of excitation sources and boundary conditions of the 3D FDTD algorithm are studied,and the absorption effect of the selected CPML boundary conditions is verified.Laplace filter is used to filter out the low-frequency noise generated by the reverse time migration imaging.It is necessary to transform the data body of the forward and backward push results to the wave number domain before imaging,and compensate the data body once in the wave number domain.The inverse transform of the data into the spatial domain,and then imaging in the spatial domain.After the Laplace denoising filter is performed on the obtained imaging profile,the amplitude compensation for the imaging data body shall be performed again.The reverse time migration imaging algorithm based on Laplace denoising is used to study the three-dimensional imaging of water-bearing collapse column in the water-rich area of mine.The column model,the cube model and the water-bearing collapse column model in the water-rich area of mine are constructed.The imaging effects of the algorithm reverse time migration imaging based on Laplace denoising are compared with that of the algorithm traditional reverse time migration imaging,and imaging of the water-bearing collapse column is performed by using the algorithm of reverse time migration imaging based on Laplace denoising.Voxler software is used to model the data set of water bearing collapse column inverse time migration imaging results,and generate the three-dimensional image of water bearing collapse column.Compared with the original model,the relative errors in x,y and z directions of the three-dimensional imaging images of water-bearing collapse column are 2.22%,5.17%and 9.17%respectively,and the overall average error is 5.52%.The shape,position and range of the three-dimensional imaging results of water-bearing collapse column are highly consistent with the original model.The simulation results show that the algorithm of reverse time migration imaging based on Laplace denoising can effectively filter low-frequency noise and achieve high-resolution imaging,and can be applied to advanced detection of rich water-rich area of mine.