Interaction Evaluation of Completion Fluids and Crude Oil in Workover Operations and Demulsifier Performance

This study investigates the compatibility of clear completion fluids, sodium chloride (NaCl), Calcium Chloride (CaCl₂), and potassium chloride (KCl) with light-gravity crude oil (API 40) during workover operations, focusing on emulsion formation and the performance of a demulsifier. The research addresses the critical challenge of emulsion-related formation damage, which hinders hydrocarbon recovery and increases operational costs. Laboratory experiments employed a 1:1 fluid-crude oil ratio, testing emulsion stability and demulsifier efficacy (TC EB 2020, at 10 ppm and 20 ppm) across temperatures of ambient, 50°C, and 75°C. Results revealed that potassium chloride exhibited the least stable emulsions (separation within 10 hours at ambient), while calcium chloride formed the most stable emulsions (36 hours at 75°C). The demulsifier proved most effective at 20 ppm, achieving the shortest separation time (1.0 hour) and lowest residual oil content (0.8%) with potassium chloride. Temperature significantly influenced emulsion stability, with higher temperatures enhancing stability, particularly for calcium chloride. The findings suggest potassium chloride as the preferred completion fluid, supported by 20 ppm demulsifier use, with pre-field compatibility testing recommended to optimize workover operations. This study contributes to industry practices by providing insights into fluid selection and emulsion mitigation, though limitations include the use of a single crude oil sample and the absence of interfacial tension data