Development and optimization of multi-objective flow modelling of pipeline rate and corrosion defect used for oil and gas

Corrosion remains a major challenge to the integrity of oil and gas pipelines in the Niger Delta region of Nigeria, often resulting in unexpected failures, oil spillage, and significant environmental degradation. This study developed and optimized a multi-objective flow modelling framework for predicting pipeline corrosion rate and corrosion defects under spatially varying conditions. Using operational data from 40 pipeline samples, a hybrid modelling approach combining artificial neural networks (ANN), nonlinear regression for mechanistic equations, and particle swarm optimization (PSO) was implemented in MATLAB. A feedforward ANN was trained to predict corrosion rate, achieving a root mean square error (RMSE) of 0.014–0.018 mm/year. A mechanistic equation incorporating temperature, flow velocity, CO₂ and H₂S partial pressures, viscosity (as a proxy for wax and solid deposition), and pH was derived as: 𝐶𝑅 = 𝑏1𝑇 𝑏2𝑉 𝑏3𝑃𝐶𝑂2 𝑏4 exp (𝑏5⋅ 𝑃𝐻2𝑆)𝜇 𝑏6pH𝑏7. Multi-objective optimization using PSO identified an optimal oil flow velocity range of 2.15–2.25 m/s, predicted to reduce corrosion rates by 25–40% while minimizing sand deposition. Sensitivity analysis revealed that fluid pH exerts the strongest negative influence on corrosion rate, while velocity and viscosity exhibit nonlinear effects. Comparative analysis showed that the proposed hybrid model outperformed conventional models such as the de Waard-Milliams and NORSOK formulations in terms of prediction accuracy. The study successfully addressed limitations in existing models by explicitly accounting for solid-liquid particle interactions and multiphase flow effects prevalent in the Niger Delta. The developed model provides a more reliable tool for pipeline integrity assessment and offers practical guidelines for optimal flow rate control. Implementation of the recommended operating velocity and modelling framework is expected to reduce unexpected pipeline failures, minimize environmental pollution, and lower unnecessary pipe replacement costs in the Nigerian oil and gas industry.