Evaluation of Induced Gas Flotation Performance for Oil-Water Separation at an Offshore Platform in the Niger Delta

Produced water treatment performance on offshore platforms in the Niger Delta remains underreported in peer-reviewed literature, limiting the evidence base for technology selection and regulatory standard-setting in Nigeria. This study evaluates the operational performance of an induced gas flotation unit deployed on a floating production, storage, and offloading vessel operating in deep water approximately 100 km offshore Bayelsa State. Performance data including inlet and outlet oil-in-water concentration, flotation cell pressure, gas injection rate, retention time, produced water volume, and demulsifier dosage were collected from the platform historian system for 12 continuous months. Average inlet oil-in-water concentration was 423 mg/L, and average outlet concentration was 18.4 mg/L, representing an average removal efficiency of 95.7%. However, outlet oil-in-water exceeded the DPR offshore discharge limit of 30 mg/L on 14% of operating days, predominantly during periods of produced water composition upsets. Statistical analysis identified influent surge events and demulsifier underdosing as primary performance impairment factors. Bayesian regression modelling indicated that the addition of a polishing hydrocyclone stage would reduce exceedance frequency to below 3% without capital-intensive upgrades. The study provides performance benchmarking data for offshore produced water treatment systems in the Niger Delta. Keywords: induced gas flotation, produced water, oil-water separation, Niger Delta, offshore platform