Empirical Modelling of Crude Oil Pipeline Spill Dispersion in Swamp Ecosystems of Bayelsa State Using CFD Simulation

Crude oil spills in the brackish water swamp ecosystems of Bayelsa State, South South Nigeria, exhibit complex dispersion dynamics governed by tidal flows, vegetation density, and seasonal freshwater flux, yet quantitative spill fate models calibrated to Niger Delta swamp conditions are absent from the literature. This study develops and validates a computational fluid dynamics model for crude oil spill transport and fate in a representative swamp channel system in Nembe Local Government Area of Bayelsa State. The model was built in OpenFOAM using a volume-of-fluid approach to simulate oil-water interface dynamics, incorporating sub-models for evaporation, emulsification, and sedimentation parameterised from field-measured crude oil properties. Tidal boundary conditions were derived from 90-day water level records at a field monitoring station. Vegetation drag was represented using a distributed porosity approach calibrated against in-situ flow velocity measurements. Model predictions of oil surface coverage area and shoreline oiling extent were validated against post-spill satellite imagery for a documented 2022 pipeline spill event, achieving a spatial prediction accuracy of 78.4% for shoreline oiling extent at 72 hours post-spill. Sensitivity analysis identified tidal amplitude and oil emulsification rate as the parameters most significantly affecting predicted spill extent. Scenario modelling results for a 10,000-barrel spill event indicated that tidal phase at spill onset altered shoreline oiling extent by a factor of 2.3. The validated model provides a practical tool for spill response planning and natural resource damage assessment in Bayelsa State swamps. Keywords: crude oil spill, CFD modelling, swamp ecosystem, Bayelsa State, dispersion