Investigation of Scale Deposition Problems and Chemical Inhibition Options in Production Tubing Strings at Total Energies E&P Nigeria Assets in Akwa Ibom State

Scale deposition in production tubing strings is a significant flow assurance challenge that reduces well productivity and increases intervention costs in offshore Nigerian operations. This study investigates the nature, severity, and distribution of scale deposits in production tubing strings at selected Total Energies E&P Nigeria assets in Akwa Ibom State, South South Nigeria. Scale samples collected during workover operations from five wells were characterised using X-ray diffraction analysis and scanning electron microscopy to determine mineralogical composition and crystal morphology. Calcium carbonate and barium sulphate were identified as the dominant scale phases, with calcium carbonate predominating in shallower completions and barium sulphate accumulating in deeper formations where formation water mixing occurs. Scale tendency modelling was performed using the Oddo-Tomson saturation index framework to predict scale onset conditions as a function of temperature, pressure, and water chemistry. The effectiveness of three scale inhibitor packages (phosphonate-based, carboxylate polymer, and sulfonated co-polymer formulations) was evaluated under simulated reservoir conditions using static bottle tests and dynamic tube-blocking experiments. Phosphonate-based inhibitors demonstrated superior performance at reservoir temperatures above 95 degrees Celsius. The study recommends the implementation of continuous chemical injection systems at the tubing head and advocates for regular water chemistry monitoring programmes to enable proactive scale management. Keywords: scale deposition, flow assurance, Akwa Ibom State, chemical inhibition, production tubing.