COMPATIBILITY OF COMPLETION FLUIDS WITH FORMATION WATER DURING WORKOVER OPERATION

Workover operations play a vital role in extending the productive life of oil and gas wells. But if the fluids used during these interventions aren’t carefully chosen, they can do more harm than good damaging the reservoir and reducing its ability to flow oil or gas. This project takes a close look at how three common completion fluids calcium chloride (CaCl₂), potassium chloride (KCl), and sodium chloride (NaCl) interact with formation water when exposed to different temperatures. Through hands-on laboratory experiments, we measured changes in key water chemistry indicators like pH, total dissolved solids (TDS), resistivity, and conductivity before and after mixing. We found that CaCl₂, although good for pressure control, led to the highest risk of scaling and the biggest drop in pH, especially in environments rich in sulfate. On the other hand, KCl proved very effective in stabilizing clays and caused minimal disruption to water chemistry. NaCl fell somewhere in between, showing relatively stable behavior and low reactivity. These findings offer valuable insights that can help engineers choose the right fluids for workover operations protecting the reservoir and improving long-term production. Keywords: Completion fluids, formation water, fluid compatibility, workover operations, calcium chloride, potassium chloride, sodium chloride, reservoir damage, scale formation, fluid selection