Method for prediction of oil well annular tube damage and detecting instrument for implementing the method

Abstract

The invention relates to a method of forecasting casing pipe damage by exploring casing pipe inner stress and the metal magnetic memory testing instrument designed specially for the method, which mainly solves the problem that prior casing damage testing technology only estimates the existed casing damage and can not forecast the possible casing damage. It is characterized in that the metal magnetic memory testing instrument is set to the objective measuring well segment; it moving along the underground casing pipe takes the normal component of leakage magnetic field Hy; The ground treatment system makes sampling data sequence x(n) is filtered in data by hanning filter; index wavelet denoising is carried out by Db4 wavelet function and four decomposed layers; denoising signal f(ti) is used to draw the magnetic memory data and grads curve; according to the curve the peak value of magnetic memory signal is taken out; the value is controlled with the four-grade semi-quantity evaluation underground casing stress distribution state table to forecast the criticality of casing damage. It has the early forecasting casing damage and can avoid huge economical loss of casing damage in oil field.

Description

Technical field: [0001] The present invention relates to a method used in oilfield logging and a logging tool specially designed for implementing this method, in particular to a method for predicting casing damage by detecting the internal stress of the casing and for implementing the method The specially designed metal magnetic memory detector. Background technique: [0002] Commonly used methods for non-destructive measurement of residual stress of materials include component drilling method, X-ray diffraction method, ultrasonic velocimeter method, laser interferometry, infrared thermal image method, and magnetic measurement method. As the component drilling method is a destructive post-test method, it is rarely used now. X-ray diffraction method and ultrasonic method are suitable for laboratory measurement, but not suitable for on-site engineering measurement applications. Like X-ray diffraction, laser interferometry can only measure the stress on the surface of the material, ...

AI Technical Summary

Problems solved by technology

[0003] In order to solve the problem that the casing damage detection technology at the present stage is only limited to judging the casing damage that has occurred but cannot predict the possible casing damage, the present invention provides a method for predicting oil well casing damage and for The metal magnetic memory detector specially designed to implement this method, after the implementation of this method, will be able to accurately and reliably detect dangerous parts characterized by stress concentration on the measured object by using the magnetic memory characteristics of ferromagnetic components, and can semi-quantitatively Evaluate the stress distribution of the casing and give the risk level, so as to achieve the purpose of early prediction of casing damage and avoid huge casing damage economic losses for the oil field

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