Numerical Investigation of Crude Oil Diffusion Dynamics and Temperature Field Evolution in Heterogeneous Porous Media Surrounding Buried Pipelines

Investigating the diffusion characteristics of leaked crude oil in heterogeneous porous media is crucial for accurately predicting the location of oil leaks from buried pipelines, emergency response, and reducing the hazards of pipeline leakage accidents. This study establishes a leakage model for buried pipelines using computational fluid dynamics methods to simulate multiphase flow in porous media, focusing on the effects of different backfill soil porosities and leakage velocity on oil diffusion and temperature field evolution. Results reveal that the diffusion process consists of acceleration, transition, and stabilization phases. At a leakage velocity of 1 m/s, the oil reaches the surface in 169 s, while velocities of 2 m/s and 3 m/s reduce this to 77 s and 48 s, respectively. Higher leakage velocities significantly increase diffusion speed, with the volume fraction of crude oil in backfill soil reaching 75.68%, 91.90%, and 95.99% at 1 m/s, 2 m/s, and 3 m/s, respectively, after 180 s. The temperature field of the soil porous media after leakage is not sensitive to changes in backfill soil porosity, and the leakage rate is one of the main factors driving changes in the temperature field.