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Method for detecting local corrosion of horizontal well sleeve pipe based on retractor drive current analysis

A technology of local corrosion and driving current, which is applied in the direction of material analysis, analysis materials, instruments, etc. through electromagnetic means, can solve the problems of large-scale promotion in difficult oil fields, high cost, and long test cycle, so as to improve the program operation speed and cost The effect of low and short measurement cycles

Inactive Publication Date: 2012-09-05
HARBIN INST OF TECH
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  • Abstract
  • Description
  • Claims
  • Application Information

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Problems solved by technology

[0004] The purpose of the present invention is to solve the problem that the current local corrosion detection method of horizontal well casing is not easy to be widely used in oil fields due to high cost, long test cycle and professional operation, and provides a method based on tractor drive current analysis. Detection method for localized corrosion of horizontal well casing

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  • Method for detecting local corrosion of horizontal well sleeve pipe based on retractor drive current analysis
  • Method for detecting local corrosion of horizontal well sleeve pipe based on retractor drive current analysis
  • Method for detecting local corrosion of horizontal well sleeve pipe based on retractor drive current analysis

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specific Embodiment approach 1

[0022] Specific embodiment one: a kind of detection method of the horizontal well casing localized corrosion based on tractor drive current analysis of this specific embodiment, its specific process is:

[0023] 1. Collect the driving current of the tractor, and convert the current into a 12-bit digital signal, and the tractor is located in the casing of the horizontal well for operation;

[0024] 2. Carry out fast Fourier transform to the obtained 12-bit digital signal, and select the sampling frequency and decomposition scale of wavelet decomposition according to the results of fast Fourier transform;

[0025] 3. Perform wavelet decomposition on the 12-bit digital signal, so that the different frequency components of the 12-bit digital signal are correspondingly distributed in different wavelet scales, and then carry out characteristic information on the wavelet coefficients obtained by wavelet decomposition or the single wavelet reconstruction signal Evaluation, the specifi...

specific Embodiment approach 2

[0029] Specific embodiment 2: This specific embodiment is a further description of the detection method for localized corrosion of horizontal well casing based on tractor driving current analysis described in specific embodiment 1. The specific process of Tsallis wavelet energy entropy calculation is as follows:

[0030] The discrete wavelet coefficients of multiresolution analysis or single-branch wavelet reconstruction signal matrix is ​​D={d(k), k=1, 2,..., N}, wherein, d(k) is the kth discrete wavelet coefficient or single branch Branch wavelet reconstruction signal, k is discrete wavelet coefficient or element position variable in single branch wavelet reconstruction signal matrix, N is data length; define a sliding data window on wavelet coefficient or single branch wavelet reconstruction signal, window width is w∈N, the sliding factor is δ∈N, and the data window is expressed as

[0031] W(m, w, δ) = {d(k), k=1+mδ, ..., w+mδ};

[0032] In the above formula, m=1, 2,...,...

specific Embodiment approach 3

[0039] Specific embodiment three: This specific embodiment is a further description of the detection method for localized corrosion of horizontal well casing based on tractor drive current analysis described in specific embodiment one or two, and step three and two in step three The specific process of outputting the local corrosion information of the casing according to the input Tsallis wavelet energy entropy calculation result by using the neuron network is as follows:

[0040] Judging the relative size of the local corrosion of the casing according to the relative size of the step up jump amplitude value in the result of the Tsallis wavelet energy entropy calculation, and judging the location of the casing local corrosion according to the moment when the step up jump appears and the crawling speed of the tractor , and then output the result of the above judgment.

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Abstract

The invention provides a method for detecting local corrosion of a horizontal well sleeve pipe based on retractor drive current analysis, which relates to a method for detecting local corrosion of a horizontal well sleeve pipe. The method solves the problem that because the prior method for detecting the local corrosion of a horizontal well sleeve pipe has high cost and long test period and needsto be operated by professional staff, the prior method is not easy to popularize in oil fields in a large scale. The method comprises the following steps: firstly, converting retractor drive current into 12-bit digital signals, carrying out quick Fourier conversion on the 12-bit digital signals, and determining sampling frequency and decomposition dimensions of small-wave decomposition according to conversion results; then, carrying out the small-wave decomposition on the 12-bit digital signals, extracting a mold maximum value, testing strangeness, and operating Tsallis small wave time entropy sequentially for decomposed small-wave coefficients or signal small-wave reconstruction signals; and finally, outputting local corrosion information of a sleeve pipe by using a nerve cell network. The invention has the advantages of low cost, short test period and high efficiency and is suitable for being popularized in an oil field in a large scale.

Description

technical field [0001] The invention relates to a detection method for local corrosion of horizontal well casing. Background technique [0002] Casing status detection in horizontal wells is an important part of production logging. In the detection of casing status in horizontal wells, the detection of local corrosion of casing is of great significance. This is because the local corrosion of casing will weaken the mechanical properties of the casing body. Strength and stress distribution in the inner cavity of the damaged casing. When the underground rock formation is dislocated or unpredictable factors generate a large external force on the casing, the casing with localized corrosion is prone to distortion, perforation, and in severe cases, it will break and directly lead to oil leakage. Even oil wells are scrapped. Accurately grasping the local corrosion of casing is of great significance for improving the accuracy of logging data, discovering potential safety hazards in ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): G01N27/00G06F17/14
Inventor 李浩昱陈继开白相林
Owner HARBIN INST OF TECH
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