Research On Cathodic Protection Potential Detection Technology Of In-service Submarine Pipelines

Submarine pipelines are an indispensable part of the development of offshore oil and gas resources.Accidents caused by the failure of submarine pipelines usually cause huge economic losses and serious ecological damage.According to statistics,corrosion damage is one of the main reasons for submarine pipeline failure.The corrosion protection of submarine pipelines generally uses a combination of external anticorrosion coating and sacrificial anode cathodic protection.However,with the increase of service life of the pipeline,the pipeline anticorrosive coating degrades continuously and the sacrificial anode is also exhausted,which causes its corrosion protection system to face the risk of failure.Therefore,the detection of the corrosion protection status of submarine pipelines has become one of the important research topics for the oil and gas companies.It is of great significance to conduct efficient and accurate detection of the corrosion protection status of submarine pipelines.The main purpose of this article is to verify the feasibility and accuracy of the cathodic protection potential detection method of in-service submarine pipelines based on the measurement of the remote reference electrode potential difference.The method has been verified through laboratory scale model tests and numerical simulation calculations.In order to further verify the effectiveness and accuracy of the submarine pipeline potential detection method based on the measurement of the remote reference electrode potential difference in the actual scale,the actual sea test of the submarine pipeline potential detection was designed and carried out.This article firstly explains the principle of the cathodic protection potential detection method for submarine pipelines based on the measurement of the remote reference electrode potential difference.Also,the theoretical basis of the scaling model method and the numerical simulation method are introduced in this paper.Then,the verification tests of laboratory scale model were designed and carried out.In these tests,scaled the submarine pipeline to an operable size in the laboratory pool,and carried out a comparison test of potential detection.The potential measured by the traditional grounding method was used as a reference,which preliminarily proved the effectiveness and accuracy of the potential detection method studied in this paper;The test pipeline model is modeled and analyzed by numerical simulation technology,and the results of the numerical simulation and the test results are mutually confirmed,which enhances the reliability of the scaled model test results,and analyzes the distribution characteristics of the environmental electric field around the pipeline.In order to further verify the effectiveness and accuracy of submarine pipeline cathodic protection potential detection technology based on remote reference electrode potential difference measurement,an actual-scale submarine pipeline test model with a total length of more than 100 meters was established in a real sea environment.The actual sea test conditions and test process were designed in detail.And then,based on the principle of potential detection,two sets of mobile potential detection devices were developed,which could realize the positioning of submarine pipelines.After the actual sea test,the potential detection device carried by the ROV was selected.The results of the actual sea test proved that the potential detection method based on the measurement of the potential difference of the remote reference electrode is effective and has high detection's accuracy.