An Applied Research Of Grey Relational Analysis And Sub-Pixel Edge Detection Theory In The Casing Damage Of Oil Well Pipe

With the increasing difficulty of development in oil and gas fields, the casing damage of oil well pipe is more and more serious. Detection and prevention of casing damage has become one of the hot research field in the oil and gas.The down hole video system is an important way to monitor the underground environment and the prevention of casing damage. Through the camera video of the inner casing wall, the casing damage image can be captured and with the edge detection of it, the degree of casing damage can be easily detected. As an important part of the grey theory, grey relational analysis has been widely used in image engineering. In this paper, grey relational analysis and Zernike moments are combined to analysis the casing damage detection and its quantitative interpretation.This paper studies the theory of grey relational analysis. Mainly introduces the definition of grey relational analysis、data preprocessing and the calculation of grey correlation degree. According to the captured noisy image which from the down hole video system, B-mode relational degree analysis is used to denoise the casing damage image.According to the image which has been denoised, the grey relational analysis is used to locate the captured image at one pixel accuracy. It solved the problem of difference in traditional edge detection operators with their results of edge detection. Then the edge point is relocated with sub-pixel level by means of Zernike moment operator to achieve sub-pixel edge detection and improve the accuracy of quantitative interpretation. In this paper, in order to improve the accuracy of edge detection, a novel method is proposed based on grey relational analysis and Zernike moment. Experiment results show that the method has better edge detection accuracy and reduce the running time of program.Finally, the casing damage of oil well pipe detection system was developed by the object oriented language. This system can provide certain guidance for the casing damage detection and Prevention. It can be used in quantitative interpretation of the casing damage and show the related casing damage data.