Original Theoretical Contribution to Modelling Gas Hydrate Inhibition Kinetics in Deep Offshore Nigerian Pipeline Conditions

Gas hydrate inhibition in deepwater production systems remains an area of active theoretical development, with existing kinetic inhibition models showing significant predictive limitations under the high-pressure, high-CO2 and high-H2S conditions characteristic of Nigerian deepwater reservoir fluids. This study develops an original theoretical model for gas hydrate inhibition kinetics specifically calibrated for Nigerian deepwater fluid and operating conditions, addressing fundamental gaps in existing kinetic hydrate inhibitor (KHI) performance prediction theory. The research employs a multi-scale theoretical development approach, beginning with molecular dynamics simulation of KHI-hydrate surface interactions for representative Nigerian gas compositions containing elevated CO2 and heavy hydrocarbons, and deriving macroscopic inhibition rate equations from atomistic-scale energy barrier calculations. The theoretical model is parameterised and validated through a comprehensive high-pressure autoclave experimental programme using synthetic gas mixtures replicating compositions from three Nigerian deepwater blocks at subsea temperatures from 2 to 8 degrees Celsius and pressures from 100 to 400 bar. The study's original theoretical contributions include: a CO2-corrected nucleation induction time model, a novel sub-cooling limit correlation incorporating acid gas partial pressures, and a KHI effectiveness degradation model accounting for brine salinity effects relevant to Nigerian deepwater produced water compositions. The validated model demonstrates superior predictive accuracy relative to published models across the Nigerian deepwater operating envelope. Industrial implementation guidance for KHI dosage optimisation is derived from the model. Recommendations include integration of the model into industry standard flow assurance software packages and a collaborative validation programme with Nigerian deepwater operators. Keywords: gas hydrate, kinetic inhibitor, deepwater Nigeria, molecular dynamics, inhibition model.