Research On Underwater Pipeline Damage Detection Based On Bilateral Acoustic Wave

Underwater pipeline is the key channel for offshore oil transportation.The damage detection of underwater pipeline can not only effectively prevent pipeline leakage accidents such as oil and natural gas,but also has important significance in the sustainable development strategy of marine resources.At present,the number of underwater pipelines in China's offshore oilfields is increasing,and the service time is getting longer and longer.It is also urgent to detect underwater pipeline damage.Traditionally detection methods are difficult to operate,has high price of testing equipment,low detection efficiency and high technical expertise.At the same time,the manual inspection of divers also revealed the disadvantages of high labor intensity,poor economic and safety,and greater impact on sea conditions and operating water depth.In this paper,the underwater pipeline with outer anti-corrosion layer was taken as the research object.According to it's echo characteristics of sound waves in no damage and detachment damage.The characteristics of underwater pipelines and damage characteristics in underwater acoustic images were taken as the detection targets.We used bilateral acoustic imaging technology to realize intuitive,fast,reliable and effective damage detection.This is of great research significance and application significance.It is supported by 2017 Major Science and Technology Special Project of Guangdong Province(2017B010118002)and 2018 Major Industrial Science and Technology Projects in Guangzhou(201802020031).The main works of this paper are illustrated as follow:(1)The acoustic scattering mechanism and echo characteristics of the underwater regular cylinder were introduced.The geometrical acoustic scattering and elastic acoustic scattering components of the echo were discussed.The finite length underwater pipeline with outer elastic medium-inner rigid medium damage acoustic scattering was constructed.This article analyzes how to select the bilateral acoustic wave technical indicators and the acoustic characteristics of the bilateral acoustic waves in the underwater environment to ensure better underwater ultrasonic imaging detection.A method for ultrasonic imaging detection of underwater pipeline damage based on bilateral acoustic waves was proposed.The mechanism of ultrasonic imaging detection of underwater pipeline damage was expounded.Based on the characteristics and detection mechanism of the bilateral acoustic waves,the overall planning of the underwater pipeline damage detection platform was carried out.(2)The characteristics of the bilateral acoustic image were analyzed.The underwater acoustic image regularization process was studied to adjust the overall gray dynamic range of the underwater acoustic image.By the advantages of bilateral filtering and multi-scale RETINEX algorithm for underwater acoustic image,a better underwater acoustic image enhancement processing effect was obtained.The underwater acoustic image pipeline damage detection technology was studied.The underwater pipeline detection and identification was carried out through used HOG+SVM algorithm.The characteristic matrix of the underwater pipeline was extracted from the underwater acoustic image,and the damage detection method of the underwater gray mean pipeline was proposed.The specific process of the underwater pipeline damage detection algorithm was determined.(3)The demand analysis of underwater pipeline damage detection imaging software was carried out.The bilateral acoustic data was analyzed and the bilateral acoustic imaging visualization design was performed.It mainly included data structure analysis and reading,data conversion and display design.The underwater pipeline damage imaging detection software module and software platform various functional modules were designed.And the specific implementation process of each functional module was described.(4)An experimental platform for underwater pipeline damage detection of intelligent unmanned ships was build.The echo simulation analysis experiment of underwater pipeline damage acoustic scattering characteristics was carried out,which provided an effective theoretical basis for the detection of bilateral acoustic imaging of the anti-corrosion layer of the underwater pipeline.The underwater pipeline suspension state detection was used as an auxiliary means for underwater pipeline damage detection.The experimental design and process planning for the underwater pipeline suspended state were carried out.Compared with multiple sets of experiments,the relative error of the underwater pipeline suspension state detection was less than 10%.The larger the suspended height was,the larger the scope of the sound shadow zone was,and the more obvious the characteristics of the sound shadow zone were.Bilateral acoustic imaging detection experiments for underwater pipeline damage were mainly aimed at the shedding damage of the outer anti-corrosion layer of the underwater pipeline.A comparative experiment was carried out on the detachment damage of the outer anticorrosion layer of three sets of different shedding sizes.The HOG+SVM algorithm was used to extract the underwater pipeline interest region,and then the gray-scale mean damage identification method was used to detect the damage.Under the experimental conditions,three groups of pipelines with different widths could be effectively detected.Compared with the traditional DC potential gradient detection method for underwater pipeline damage,the results of damage detection rate can reach more than 90%,positioned accuracy of the underwater pipeline was about plus or minus 0.1m,and detection efficiency was increased by more than 60%.As the width of the outer anti-corrosion layer increased(the size of the shedding increased),the bilateral acoustic imaging was better.