Lightning overvoltage protection for oil and gas pipelines adjacent to power lines with consideration for current dispersion in soil

Abstract

[Objective] In light of a growing number of oil and gas pipelines crossing or running near power lines,the issue of lightning overvoltage at these locations has garnered increasing attention within these two industries. [Methods] In this study,a calculation model was developed using COMSOL Multiphysics software to depict the generation mechanism of potential difference between pipelines and their anticorrosive coatings at locations where these pipelines cross or run near power lines.Simulation calculations were performed to analyze the impact of soil resistivity and soil layering on pipeline overvoltage amplitude.As a result,a pipeline overvoltage protection method was proposed,considering the dispersion of current over the grounding grids at nearby towers/poles. [Results] The simulation results confirmed the effectiveness of the proposed optimization solution in limiting the voltage,establishing its practical application value.Although the potential on the pipelines and the withstand voltage of their anticorrosive coatings were generally balanced,the difference between them was notably influenced by the direction of current dispersion from the grounding electrodes.Under typical soil resistivity conditions,the withstand voltage difference between the pipelines and their anticorrosive coatings remained within limits.Additionally,it was observed that individual lightning discharges alone were insufficient to cause breakdown in the three-layer polyethylene (3PE) anticorrosive coatings.However,the withstand potential difference did contribute to the enlargement of local damage points that already existed within the coatings.To mitigate the withstand potential difference,an effective approach is proposed involving adjustments to the included angle and relative distance between the pipelines and grounding electrodes at nearby towers/poles. [Conclusion] It is proposed to effectively reduce the potential difference between pipelines and their anticorrosive coatings by modifying the configuration and current dispersion dimensions of the grounding grids at nearby towers/poles.With proven technical feasibility and economical efficiency,the findings of this study serve as a valuable reference for the design,construction,safe operation,and maintenance of oil and gas pipelines.

Keywords

• oil and gas pipelines
• crossing or running in proximity
• lightning overvoltage
• current dispersion in soil