Analysis Of Acoustic Waves Of Well Down-hole Tubing Leakage Based On HHT

The down-hole tubing have been in the environment of high temperature and high pressure for a long time during the productive process,so,it is very common for perforation leakage of the tubing.How to realize the detection of underground leakage in the ground has become a urgent problem to solve.The acoustic wave method presents high accuracy in detecting leakage,which is applied to detect the leakage of the tubing in this study.However,several current time-frequency analysis methods are not applicable for the collected unsteady acoustic wave signals.Therefore,a novel time-frequency analysis method which could effectively extract leakage acoustic signal characteristics should be developed as soon as possible.Accordingly,the following studies are carried out for this purpose:(1)The existing acoustic wave monitoring system working on the ground for the tune leakage was used for indoor experiment,it is to perform a simulation of a leaking state with different pore diameters and pressure differences.Simultaneously,the signal was recorded and stored by the acoustic wave acquisition devices,which provides the experimental basis for analyzing the relationship between the acoustic signal and the leakage holes;(2)Chrip signals possessing similar properties with unsteady acoustic signals are selected as simulation analog signals,which are analyzed by three time-frequency analysis methods: STFT,WT,and HHT.Based on the results,their time-frequency characteristics(i.e.,the level of resolution)are compared to each other,which could provide the reference for the determination of analysis methods;(3)HHT was used to analyze the acoustic signal of the tubing leakage collected in the indoor test,and the instantaneous amplitude map,instantaneous frequency map and Hilbert marginal spectrum were obtained.The peak value of the instantaneous amplitude of the signal was selected as the characteristic parameter.With the linear regression analysis,the relationship between the size of the leak hole and the amplitude of the acoustic signal was derived,providing a basis for solving the size of the leak hole in an unknown tubing;(4)The tubing leakage detection experiment was conducted on the offshore platform,where the Hilbert spectrum analysis was performed on the acoustic data of wells A and B respectively.Finally,the size of the downhole leak aperture was inferred using the formula,which provided data support for the subsequent tubing repair.