Professional Evaluation of Production Chemistry Programmes for Asphaltene Deposition Management in High-API Gravity Crude Oil Wells of Deepwater OML 130, Offshore Nigeria

Asphaltene deposition is a flow assurance challenge in certain deepwater Nigerian crude oil systems where the compositional characteristics of high-API gravity condensate-like crudes create conditions of marginal asphaltene stability, particularly during depressurisation near the wellbore and at choke valves. This study professionally evaluates production chemistry programmes for asphaltene deposition management in deepwater OML 130, operated by Total Energies, offshore Nigeria. Crude oil samples from four producing wells were characterised for SARA composition using the IP-143 fractionation method, and asphaltene stability was assessed using the Colloidal Instability Index and near-infrared spectrophotometric titration methods. Asphaltene onset pressure was experimentally determined as a function of pressure and temperature for each sample, revealing onset pressures 300 to 550 psi above the bubble point pressure for three of the four crude streams. Commercially available asphaltene inhibitor and dispersant packages were screened using high-pressure near-infrared spectroscopy in recombined sample tests. A co-polymer inhibitor package demonstrated a 74 percent reduction in asphaltene deposition tendency at a dosage of 100 parts per million in the most problematic crude stream. Continuous injection system design and umbilical chemical delivery specifications are developed for the recommended treatment programme. Economic analysis confirms treatment value exceeds intervention costs by a factor of 6.3 over the well life under base production assumptions. Keywords: asphaltene deposition, flow assurance, production chemistry, OML 130, deepwater Nigeria.