Modeling Direct-Current Interference on Pipelines with Zero Potential at Infinity Through Electric Field Decomposition

Abstract

Oil and gas pipelines are susceptible to direct current interference from nearby third-party cathodic protection or direct current transmission systems. This paper proposes a new method for analyzing direct current interference and its mitigation measures. The proposed method is based on the boundary element method of analyzing cathodic protection systems and direct current interference. Infinity is used as the zero-potential point instead of the pipeline itself. The soil potential near the structure is divided into the cathode electric field, the anode electric field, and the electric field generated by direct current interference. The proposed method was validated to be effective for modeling these electric fields. The results indicate that interference shifts the pipeline’s body potential positively or negatively compared with that in its normal cathode state. The interference was categorized on the basis of whether it was generated by the anode or cathode electric field, and mitigation measures were designed for each type of interference through electric field cancellation.