Research on an Improved Evaluation Method and Improvement Strategy for the Transportation Capacity of Submarine Cable in a Directional Drilling Section

The submarine cable installed in the directional drilling pipeline may face constrained ampacity due to the narrow air gap and complex thermal environment. The current studies have overlooked the axial heat transfer caused by variable burial depth and the influence of deep ground temperature, resulting in inaccurate assessment of the hot spot temperature and hot spot location of submarine cable in the directional drilling pipeline. To address this issue, the distributed parameter electrical circuit model for long-distance submarine cable and the three-dimensional thermal simulation model for the submarine cable landing section were developed to analyze the heat generation and dissipation characteristics of submarine cable in the directional drilling pipeline. Then, the hot spot location of submarine cable in the directional drilling pipeline was identified. Subsequently, an improved thermal rating method based on the quasi-three-dimensional thermal model was proposed to rapidly assess the hot spot temperature for the submarine cable in the directional drilling pipeline. The accuracy of the improved thermal rating method was verified by comparison with the simulation method. Finally, implementation of water circulation was conducted to resolve the overheating issue in the directional drilling pipeline. The investigations in this paper can provide support for the efficient utilization of submarine cable. The improved evaluation method for submarine cable in a directional drilling section proposed in this paper can be regarded as the supplement to the traditional IEC method.