Research On The Model And Law Of The Cathodic Protection Potential Distribution Of Cross Pipelines

With the rapid increase in the construction of oil and gas pipelines,the cross-cutting problem of oil and gas pipelines is inevitable.When the pipelines cross,interference problems between the cathodic protection systems occur,resulting in DC stray current corrosion in a certain pipe section.Different from the cathodic protection potential distribution of the conventional single pipe,the pipe crossover not only changes the cathodic protection potential distribution of the two pipes,but also changes the cathodic protection potential.Therefore,it is necessary to study the cathodic protection potential distribution when the pipeline crosses,and determine the potential location of the DC stray current corrosion of the pipeline by the magnitude of the cathodic protection potential.At present,although ANSYS,COMSOL and other software can be used to simulate the potential distribution when the pipeline crosses,the model study of the cross-channel cathodic protection has not been found.Therefore,based on the modeling idea of the cathodic protection potential distribution model of the conventional single pipe,the cathodic protection potential distribution model of the cross pipe is established,and the boundary element method is used to solve the cathodic protection potential distribution model of the cross pipe.Boundary element method is used to solve the mathematical model of cathodic protection potential distribution in cross-channel.It is based on Gaussian divergence theorem and Green’s formula.The weighted residual method is used to calculate the Laplace equation by using the basic solution of Laplace equation as the weight function.The boundary conditions are transformed into integral equations on the boundary,and the boundary of the field is discretized by the tube element to obtain an algebraic equations containing unknown potentials and current values.The key to solving algebraic equations is to require the coefficients of algebraic equations.In this paper,the crossover physical model of the pipeline is represented in the oblique coordinate system,and the coefficient solving formula is derived by analytical method combined with the Simpson formula in numerical analysis.Finally,the cathodic protection potential distribution when the pipelines intersect is obtained by programming.In this paper,the boundary element method is used to solve the mathematical model of cathodic protection of cross-pipeline.The simulation has more simplifications.The influence parameters are considered less.Although the cross-channel cathodic protection potential can be calculated,the calculation result has a large error.Therefore,software simulation is used to calculate the distribution of cathodic protection potential in the cross-channel.In recent years,COMSOL software is often used in the calculation of cathodic protection potential distribution,and the calculation results are in good agreement with the actual engineering data.Therefore,COMSOL software is used to simulate the distribution of cathodic protection potential when the pipeline is not crossed and crossed,and the distribution law of cathodic protection potential of the cross-channel under various influencing factors.According to the results of software simulation calculation,it provides reference for the design and operation maintenance of cross-channel cathodic protection.