Investigating the effects of reaction time on scaling dynamics in produced water and its implications for enhanced re-injection practices

Produced water, major byproduct of oil production, presents significant environmental challenges due to its volume and toxicity. Effective management through re-injection is the most environmentally and economically viable approach, yet inorganic scale precipitation from incompatible water mixing poses a critical challenge. Compatibility investigations are essential to understand scale types and quantities before substantial investments, with reaction kinetics playing a pivotal role. This study examines the impact of reaction time on scale precipitation in produced water management, relevant to desalination processes such as pre-treatment and brine disposal. Water samples from two oil-producing fields were mixed, with field facilities allowing either immediate reinjection or 14-day retention. Precipitated scales were filtered from one container after 1 day and from another after 14 days under operational conditions. Results showed that scales filtered after 1 day exceeded 500 mg/L, while those after 14 days were below 150 mg/L, indicating over 350 mg/L of scales re-dissolved into the liquid phase. SEM-EDX analysis revealed that some scales increased in precipitation after 14 days, while others re-dissolved. These findings highlight the critical role of chemical reaction kinetics in scale precipitation, offering insights for optimizing pre-treatment and re-injection systems, enhancing scale management and environmental sustainability in produced water treatment.