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Borehole radar imaging method based on non-uniform spectrum estimation

A borehole radar and spectrum estimation technology, which is applied in the direction of radio wave reflection/re-radiation, using re-radiation, and measurement devices, can solve the problems of restricting the application of borehole radar, high computational complexity, and low imaging efficiency, and achieve Avoid the effect of large-scale calculation, high imaging accuracy, and stable imaging performance

Inactive Publication Date: 2018-06-19
UNIV OF ELECTRONICS SCI & TECH OF CHINA
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

However, for borehole radar data with non-uniform spatial sampling, the Stolt migration algorithm can only use discrete Fourier transform to obtain the frequency wavenumber spectrum of the sampled data, which has high computational complexity and reduced imaging efficiency
[0007] The existing radar imaging algorithms have poor performance in practical engineering applications of borehole radar, especially when processing non-uniform spatial sampling data, the imaging efficiency is low, which restricts the application of borehole radar in actual engineering

Method used

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  • Borehole radar imaging method based on non-uniform spectrum estimation
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Embodiment 1

[0046] Such as figure 1 As shown, the present invention comprises a kind of borehole radar imaging method based on non-uniform frequency spectrum estimation, comprises the following steps:

[0047] Step A, initializing the borehole radar sampling data and establishing a displacement data vector table;

[0048] Step B, using the spectrum estimation algorithm to quickly obtain the spectrum of the non-uniform spatial sampling data;

[0049] Step C, performing an interpolation operation on the estimated frequency spectrum of the sampling data obtained in the previous step to obtain the target spatial frequency spectrum;

[0050] Step D, obtaining the target space image.

[0051] During the working process of the borehole radar, the time-driven radar system will inevitably rub against the wellbore wall when moving along the wellbore, resulting in uneven spatial sampling of the system along the wellbore direction, thereby affecting the high efficiency of the target space. Imaging...

Embodiment 2

[0055] In this embodiment, on the basis of Embodiment 1, the specific implementation steps are described by taking two-dimensional borehole radar detection as an example, preferably as follows: obtaining the sampling data of the borehole radar in step A includes the following steps:

[0056] A1. Use the borehole radar system to sample the radar echoes of the medium around the well, and establish a non-uniform sampling data matrix u of several dimensions. The expression of u is as follows

[0057]

[0058] Use sliding filtering to remove the direct wave signal and other crosstalk signals in the non-uniform sampling data matrix, and at the same time use the positioning system to measure the position of the downhole system and record the displacement information, and establish the displacement data vector table [z x] of the corresponding dimension, including the uniform sampling dimension set z and non-uniform sampling dimension set x, where z and x are both single-dimensional ...

Embodiment 3

[0061] This embodiment is preferably as follows on the basis of the above-mentioned embodiments: in step B, the specific steps of using the spectrum estimation algorithm to quickly obtain the frequency spectrum of the non-uniform spatial sampling data are as follows:

[0062] B1. Establish the frequency wavenumber spectrum expression U of sampling data matrix u, wherein

[0063]

[0064] is the element of matrix U, Δx n is the actual sampling interval on the x dimension, Δx is the average sampling interval on the x dimension, n'=-N / 2+1,...,N / 2, l'=-L / 2+1,...,L / 2 , perform fast Fourier transform on all uniformly sampled dimension sets z of the sampled data matrix, and obtain partial spectral representations under uniformly sampled dimensions

[0065] B2. Comprehensively consider the estimation error and computational complexity of the frequency wavenumber spectrum of the sampling data matrix, and select an appropriate oversampling coefficient m and estimation index q;

...

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Abstract

The invention discloses a borehole radar imaging method based on non-uniform spectrum estimation. The method comprises the steps of (A) initializing borehole radar sampling data and establishing a displacement data vector table, (B) quickly acquiring spectrum of non-uniform space sampling data by using using a spectrum estimation algorithm, (C) performing interpolation on an estimated spectrum ofthe sampling data obtained in the previous step to obtain a target spatial spectrum, and step (D) obtaining a target spatial image. Through the above principle, the high-efficiency and accurate imaging of the non-uniform sampling data is improved under the premise of ensuring the imaging quality of a borehole radar, and the practical application value of the borehole radar is improved.

Description

technical field [0001] The invention relates to the technical field of borehole radar target imaging, in particular to a borehole radar imaging method based on non-uniform spectrum estimation. Background technique [0002] As a new type of deep geophysical detection technology, borehole radar can perceive targets thousands of meters deep underground (such as abnormal geological structures such as cracks and cavities), and obtain information such as the distance, orientation, shape and electromagnetic parameters of the target. Borehole radar has been widely used in void and fracture detection, hydrogeological research, greenhouse gas tracking, mineral exploration, salt dome survey and well logging, and many other fields, and has received extensive attention from all over the world. [0003] Borehole radar continuously receives echoes from the medium around the wellbore during its movement along the wellbore, and obtains the distribution information of the medium around the we...

Claims

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Application Information

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IPC IPC(8): G01S13/89G01S7/41
CPCG01S7/41G01S13/89
Inventor 杨海宁李娜李廷军黄昌瑞江海峰樊勇
Owner UNIV OF ELECTRONICS SCI & TECH OF CHINA
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