Research On The Physical Scale Modeling Spatial Data Acquisition And Analysis Of Borehole-surface Electromagnetic Method In Frequency Domain

Borehole-surface electromagnetic method (BSEM) is an electromagnetic exploration method. For the traditional ground electromagnetic exploration method,BSEM can be closer to the deep target body, which is beneficial to the effective response signal. The working principle is to put the vertical bipolar source into the well, in the vicinity of the target body to send different frequency of positive and negative interactive square wave signal, and at the same time in the ground to receive electromagnetic response signal, according to the received electromagnetic response component to reverse the underground power Sexual structure.With the rapid development of computing technology, using the finite difference equation, integral equation, finite element method and boundary element and other numerical methods to solve some of the three-dimensional complex ground conditions under the conditions of the electromagnetic response to the reality, but the geological rock mineral changes, Shape and production complex, numerical simulation still exists many difficult to solve the problem, its approximation degree and correctness also need further verification. And the physical scale modeling can be repeated, and can be used to understand a variety of geological model of electromagnetic response and abnormal target body response law, can also be used to verify the correctness and approximation of numerical simulation. In geophysical exploration of geophysics, the geodetic model is often reconstructed by appropriate proportions (usually between 1:100 and 1: 1000000) according to similar criteria, and the scale model response is converted into equivalent idealized feet model response, to verify the correct working methods and geoelectric response characteristics or exploration effects.At present, the physical scale modeling of borehole-surface DC electrical method is relatively mature, and the physical scale modeling of BSEM response to the well is still relatively small. Therefore, in order to study the electromagnetic anomaly response characteristics of the oil and gas reservoir model, In this paper, the physical scale modeling of BSEM in the frequency domain is studied, and the spatial distribution characteristics of the electromagnetic field in the frequency domain are further studied, which can be helpful to verify the correctness and approximation of the new numerical simulation. This paper based on the national natural science fund projects well in frequency domain electromagnetic method of numerical simulation and physical scale modeling study (41574065), the physical scale modeling as the main means, collected well electromagnetic flume simulation experiment system of spatial data, mainly study the BSEM field space distribution characteristics, the three dimensional goal body borehole-surface response characteristics. On the basis of this,the spatial response characteristics of the three-dimensional target are obtained by making the thin plate and the mound model of the different resistivity, and the electromagnetic field simulation of the frequency domain of the anomalous body is carried out, and the approximate solution of the new numerical simulation is obtained Sex and approximate degree to provide experimental support. In this paper, the spatial data acquisition and analysis of electromagnetic physics in the frequency domain are studied. The main results are as follows:1) Setting the size, materials and the resistivity of the physical scale modeling according to the principle of similitude and the size of the tank.2) We obtained the frequency band of the excitation and the time interval of the sampling according to the principle of similitude.3) After four different physical model with different electrical resistivity and shape were made, and an arc-spark stand was designed (which is used for underwater data acquisition), we measured the data of 285 response points for each model to collect the spatial distribution signal response by Borehole-surface electromagnetic method.4) After obtaining the spatial response of four different models, we processed the measured data. The result shows that: The total field and background field of different model spatial data appear high peak on both sides of y = 0, and the harmonic curve of anomaly field is also high peak on both sides of y = 0 plane, and the anomalous field Indicating the existence of abnormal bodies; By comparing the Ey component of the total field curve, we come to a conclusion: When away from the source line, the value of the total field Ey component decreases with the depth of the acquisition increases;For the points near the source, the value of the total field Ey component increases with the depth of the acquisition increases. This spatial distribution feature provides experimental support for verifying the approximation of numerical simulation.