Simulation Study on Ultrasonic Testing of Defects in Cement Sheath
Various defects in cement sheath may lead to accidents such as interlayer cross flow and wellhead under pressure.Nondestructive testing(NDT)is a technology that can detect the defects in the cement sheath.Based on the propagation pattern of ultrasonic waves in continuous media,the COMSOL simulation software was used to simulate the piezoelectric effect and the propagation state and reflection law of ultrasonic waves in cement sheath,and identify the relevant characteristics of reflected signals of defects in the cement sheath.The results show that when a 1.0 MHz 5-period Hanning window modulated ultrasonic sine wave is selected as the excitation signal,the ultrasonic probe can receive the reflected signal of cement sheath defects within 50 μs.Among different types of defects,the rectangular defects have the best detection effect.When the principal direction of the defect is perpendicular to the direction of ultrasonic incidence,the detection effect is the optimal.The ultrasonic NDT tech-nology can quickly and accurately determine the type and location of defects in the cement sheath.Meanwhile,ad-justing the angle of ultrasonic incidence can help improve the detection effect.The study results provide certain guidance for the application of ultrasonic wave in the detection of defects in cement sheath.
cement sheath defectnondestructive testingultrasonic wavedefect typeultrasonic incidence direction