COLLOIDAL SYSTEMS IN PRODUCED WATER: COMPARISON OF DIFFERENT OPERATIONAL STAGES

One of the challenges during oil production is managing the high volume of produced water (PW), which must be treated before reinjection or disposal. Its chemical composition is complex, varies depending on the field, and includes dissolved inorganic and organic compounds, dispersed hydrocarbons, gases, and suspended solids. Hence, PW often consists of colloidal systems, such as emulsions, suspensions, or micellar and polymeric solutions, which are challenging to separate, causing operational, economic, and environmental problems. Therefore, understanding their colloidal structure can improve PW treatment to guarantee efficient injectability or safe disposal. In light of colloid physical chemistry, this study aims to characterize PW from different stages: production riser (PR) and flotation tank (WIF). It is worth mentioning that some additives were used between the two stages and can also impact the formed colloids. Characterization of PW samples was conducted before and after centrifugation or filtration. Optical micrographs showed that both samples were oil-in-water emulsions also containing suspended solids. However, the amount of oil and solids differed between PR and WIF. Surprisingly, WIF had much higher turbidity than PR, likely due to solid agglomerates. Laser diffraction revealed particle medians of 9.0 and 8.2 µm for PR and WIF, respectively, although their distribution curves were different. Centrifugation and filtration reduced particle size, turbidity, and absorbance by removing solids and oil. These results showed that samples from different operational stages can have different colloidal behavior due to chemical additives and separation processes. Continuous study in this field is essential for understanding the mechanisms of colloidal systems to optimize industrial operations.