| The basic principle of magnetotelluric sounding method determines that the method is susceptible to the interference of various noises.In magnetotelluric sounding field collection work,if there are any obvious interference sources,such as high voltage power lines,large industrial equipment,although you can choose to avoid a certain distance to reduce noise effects,but with the rapid development of economy in our country,traffic is becoming more and more convenient,especially in large and medium-sized cities around,high-speed rail network is very dense,making it around the city for magnetotelluric sounding work very difficult.How to obtain high-quality magnetotelluric sounding data is an urgent problem to be solved without avoiding the influence of high-speed railway.Therefore,it is of great significance to carry out research on magnetotelluric sounding data processing technology under the influence of modern high-speed railway interference signals.In this paper,the Beijing-Zhuozhou section of Beijing-Guangzhou high-speed railway is taken as the source of interference.In order to study the effect of high-speed railway on mt sounding,based on the project of"Investigation and evaluation of deep carbonate heat storage in Hebei central depression"undertaken by the institute of geophysical and geochemical exploration of Chinese academy of geological sciences,this paper carried out mt anti-jamming test for the interference source of HSR.In the experiment,the characteristics of interference signals generated by high-speed railway are studied by means of the measured magnetotelluric data from test points at different distances from high-speed railway lines.By analyzing the apparent resistivity and phase curves of each point obtained from conventional processing,the interference characteristics of high-speed railway on the magnetotelluric sounding data,such as interference frequency band and interference distance,are obtained,and the influence law of high-speed railway is summarized.On the basis of conventional remote reference processing technology,according to the remote reference principle,carry out remote reference test:take multiple remote reference points in different directions and at different distances.Data collection was conducted at the same time as the experimental points.The test site data were processed respectively,and the processing results were compared and analyzed.The effective remote reference points were selected and the selection principles were summarized.However,the comparison results showed that single remote reference was difficult to improve the data quality of the whole frequency band.In view of the problems of the remote reference method,the paper proposes the multi-point remote reference processing technology,selects the appropriate multiple remote reference points to process the noisy data,and obtains the apparent resistivity curve and phase curve with good data quality in the whole frequency band.Compared with the conventional single point remote reference method,the multi-point remote reference method has better processing effect and can get more reliable dataIn order to verify the effectiveness and reliability of the multi-point remote reference method,on the basis of actual test data,combining theory with practice,Chose a more severe influence of the high speed rail profile,respectively with conventional method,multipoint remote reference method for processing,and the inversion results compared with seismic profile,found far more reference magnetotelluric geological interpretation results are basically consistent with seismic geological interpretation,proves that the method is feasible,and the geological interpretation of magnetotelluric sounding profiles. |
