Related identification method for transient electromagnetic weak polarization response

Abstract

The invention belongs to the technical field of transient electromagnetic exploration, and particularly relates to a transient electromagnetic weak polarization response correlation identification method, which comprises the following steps of S1, setting a sampling rate according to a working requirement, selecting a transmitted waveform according to an autocorrelation function, and determining a transmitting parameter; s2, starting transmitting work, and transmitting for one pseudo-random sequence period to serve as a pre-disturbance signal; s3, continuing to transmit the pseudo-random sequence of the next period, and performing full-time sampling on the transmitted waveform and the ground response; s4, stopping transmitting and sampling, and superposing the transmitted waveform and the earth response to obtain a mean value to form transmitted waveform data and earth response data with a periodic pseudo-random sequence length; and S5, respectively calculating a cross-correlation function of the transmitted waveform and the earth response data, carrying out correlation identification calculation, and solving a transient electromagnetic weak polarization response of a periodic pseudo-random sequence length. The transient electromagnetic weak polarization response observation method is used for improving transient electromagnetic weak polarization response observation accuracy and providing reliable observation data for subsequent interpretation work.

Description

technical field [0001] The invention belongs to the technical field of transient electromagnetic exploration, and in particular relates to a correlation identification method of transient electromagnetic weak polarization response. Background technique [0002] Transient electromagnetic method (TEM) is a time-domain electromagnetic prospecting method. The basic principle is to use a grounded or ungrounded emission source to establish a steady magnetic field in the detection area, and then turn off the field source instantaneously. According to Faraday's law of electromagnetic induction, in the underground medium A secondary field that changes with time will be induced, and the induced transient electromagnetic response will be observed and recorded, and the electrical distribution of the underground medium can be inferred through theoretical and numerical simulation analysis. [0003] Due to the induced polarization characteristics of the earth, under the action of ground em...

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Problems solved by technology

Different from the fast attenuation speed and large initial amplitude of the induction field, the polarization field generally has a small amplitude and slow attenuation speed, so the polarization response shown on the transient electromagnetic curve is generally weaker and more susceptible to interference, and Appeared later

In order to collect more accurate and complete transient electromagnetic weak polarization responses, it is necessary to carry out multiple long-period repeated observations, which requires high time costs and is not economical and practical.

On the other hand, due to the limitation of the repeated observation method, the level of interference suppression depends on the number of observations n, only n -1 / 2 The speed decreases, and it is difficult to obtain good measurement results even if a large amount of observation time is spent when the interference is strong

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