NUMERICAL ANALYSIS FOR CATHODIC PROTECTION SYSTEM OF COMPLEX DEEP WATER OIL PLATFORM JACKET

摘要

Boundary Element Method (BEM) was used to assess the layout of sacrificial anodes and to give the distributions of potential and current density. An experiment was designed and used to give special polarization curve with calcareous deposits during flowing seawater. The polarization experiment for small jacket and the monitoring experiments for actual jacket were carried out separately. A revised boundary element model of cathodic protection system of the complex deep water oil platform jacket was built. Some hypothesis conditions for cathode, anode and insulated surface of this complex jacket were defined. Traditional cubic insulated boundary of BEM was replaced by revised cuboid insulated boundary. Numerical calculation and experiment for cathodic protection system of a small experimental jacket in lab indicated that the boundary element model and these hypothesis conditions were correct and reasonable. Then the model and hypothesis conditions were used to simulate cathodic protection system of the complex deep water oil platform jacket. The distributions of potential or current density of whole jacket, bottom, skirt piles and complex joint are given. Monitoring data of potential and current density are given. Analysis for numerical calculation data and monitoring data prove that the values of numerical calculation from BEM are very close to the actual values. So the results of numerical calculation made by BEM are correct. The cathodic protection system of this complex jacket has achieved uniform distribution of potential and current density and reached the requirement of Standard.