Modeling and Experimental Analysis of Low-Viscosity/High-Permeability Sealant Penetration Dynamics in Oil-Filled Submarine Cables

Insulating oil leakage from oil-filled submarine cables compromised operational integrity and posed environmental risks. This study proposed a novel sealant-plugging repair technique that combines low-viscosity/high-permeability sealant permeation and high-viscosity/low-permeability sealant replacement and pressurization. The permeation process of the low-viscosity sealant, from the injection port to the outlet, was visualized using the Volume of Fluid (VOF) method. Analysis focused on: (1) sealant volume fraction in the sealing cavity; (2) sealant leakage volume fraction along the radial gaps at outlet 2; and (3) relative velocity of the permeating sealant along the radial gaps at outlet 2. Application of 0.4 MPa of sealant pressure achieved the key balance, characterized by: (i) Completed displacement of air from the sealing cavity; (ii) Full permeation of sealant into the gaps between the armored copper strip gaps and the radial gaps; (iii) Avoidance of the excessive sealant leakage flow observed at 0.5 MPa, promoting efficient sealant usage; (iv) A short time to reach permeation and leakage steady state. This study demonstrated the feasibility of the low-viscosity sealant penetration into both the gaps between the armored copper strips and the radial gaps under 0.4 MPa injection pressure. It provided theoretical and experimental guidance for this process within the sealant plugging repair technique.