System and method to detect the crack width between the cement outside drivepipe and the drivepipe

Abstract

The invention discloses a system and method to detect the crack width between the cement outside a drivepipe and the drivepipe. The method comprises the following steps: inputting the already known parameters of a to-be-measured model into a data processing terminal and setting the emission frequency of the ultrasonic waves and the emission cycle; then placing the to-be-measured model into a model container; filling the drivepipe with liquid until it is full; covering the top cover onto the model container; setting the detection position and the detection azimuth angle through the adjustment of the rotation of the axial rotation stepping motor and the hoisting stepping motor through the data processing terminal; controlling the emission of the ultrasonic probe and the reception of the echo by the data processing terminal through the data acquisition control module; carrying out fast Fourier transform on the waveform data of the echo by the data processing terminal to seek the frequency data of the echo signal; and then using the spectral information of the reflected wave in the drivepipe resonance transmission window to establish an inversion objective function; and through the improved differential evolution algorithm, obtaining the minimum value of the objective function so as to obtain the crack width between the cement outside the drivepipe and the drivepipe. Tested by experiment, the maximum relative average error between the actual value and the measured value is less than 0.178 mm.

Description

technical field [0001] The invention relates to the technical field of drilling and cementing in oil and gas production, in particular to a system and method for detecting and measuring the thickness of the gap between the cement outside the casing and the casing at a specified azimuth by using ultrasonic waves in the casing. Background technique [0002] The cementing cement strength evaluation experiment is to evaluate the cementing effect of various cements, and it is of great significance to guide the cementing construction on site. The detection of the thickness of the fluid layer outside the casing is one of the key steps in this experiment. At present, among the main methods for detecting the parameters of the medium outside the casing, the ultrasonic reflection method has been extensively studied because of its high circumferential resolution. However, when this method quantitatively inverts the parameters of the medium outside the casing, it mainly faces the follow...

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Problems solved by technology

In the process of searching for the extremum of the objective function, in order to solve the problem of difficulty in searching the extremum of t

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