Research On The Signal Preprocessing And Inversion Technology Of Borehole Radar

As an efficient non-destructive detection method,borehole radar can work in deep formations such as oil fields and gas wells.Be constrained by the complexity of the environment and the limitation of the detection conditions,it is more difficult to guarantee the data quality than the conventional ground penetrating radar in practical engineering application.Therefore,how to extract the effective information from the borehole radar data and reflect the formation information is the focus of international research.There is no unified international standard for borehole radar system.Due to the complex data transmission,limited data transmission speed and data easily polluted by complex environment,how to extract effective data from the original data and carry out real-time control and monitoring of borehole instruments is the primary problem for borehole radar system data processing Questions.This paper mainly focuses on the signal processing of borehole radar,and the main contents are as follows.Firstly,the model of borehole radar signal and the common calculation method of borehole radar are described.Starting from the borehole radar signal,the signal model of borehole radar signal and the data type of borehole radar are deduced,the signal analysis content of borehole radar is described,the basis of borehole radar data processing is established through mathematical model,and the conventional data processing flow is realized by programming.Based on Maxwell equations,the forward calculation borehole radar simulation calculation is described completely through the derivation of calculation process and one-dimensional finite-difference time-domain calculation.Then the calculation method is extended to high-dimensional,so that the simulation calculation closer to the real model can be carried out.On this basis,in the methods of signal preprocessing,the method based on EMD decomposition has excellent performance of borehole radar signal processing adaptability.Starting from the EMD decomposition algorithm,the time-frequency domain decomposition algorithm of borehole radar signal preprocessing is analyzed.Expanding to high dimension,the two-dimensional signal of borehole radar is processed,which can effectively ensure the signal quality.Through the decomposition of time-frequency domain,the signal processing work has a better time-frequency analysis.This paper also introduces the 3D slice imaging of borehole radar energy,which can visually analyze the energy echo and greatly improve the ability of the borehole radar data to analyze geological data.Finally,this paper studies the inversion of borehole radar time-domain waveform,deduces and optimizes the inversion equations,and carries out simulation programming verification.The simulation results show that the inversion calculation scheme of borehole radar based on least square can achieve good convergence results,and can reproduce the electromagnetic parameters of cylindrical targets.Through the combination of migration imaging and grid generation method,a response scheme for the well radar target is proposed.The inversion calculation of cylindrical target shows that this method can effectively reduce the workload and complexity of inversion calculation,and the inversion of the model is good.