CFD Simulation of Multiphase Flow in Pipelines: Implications for Flow Assurance in Niger Delta Mature Fields

Multiphase flow in horizontal pipelines poses significant flow assurance challenges in Nigeria’s Niger Delta mature oil fields, where declining production, high water cut, variable gas-oil ratios, and aging infrastructure frequently lead to slugging, pressure surges, hydrate formation, wax deposition, and corrosion risks. This study employs Computational Fluid Dynamics (CFD) using OpenFOAM’s interFoam solver (Volume of Fluid method) to simulate oil-gas-water flow in a representative 8-inch horizontal pipeline (50 m length) under three realistic operating conditions typical of onshore/swamp gathering lines. The simulations reveal dominant flow regimes (stratified-wavy, transitional slug, and high-gas slug/annular), with detailed analysis of phase fraction contours, velocity profiles, axial pressure drop, and wall shear stress distribution. Case 2 (u_sl = 1.2 m/s, u_sg = 5.0 m/s) exhibits moderate slugging with pressure oscillations of 800–1200 Pa and shear stress peaks of 10–18 Pa at slug fronts, highlighting elevated erosion/corrosion risk zones. The findings provide predictive insights into flow instability and blockage risks in aging Niger Delta assets, offering practical recommendations for chemical inhibition, pipeline design optimization, and operational strategies to enhance production stability and support enhanced oil recovery initiatives under indigenous operators.