Abstract
The residual level analysis related to scale inhibitors in produced water using offshore methodology is the key challenge in inorganic scale management, therefore proposal of simple and fast analytical techniques is mandatory. The objective of this work is to quantify residual polymeric scale inhibitors in produced water from a Brazilian post-salt well A using the solid-phase extraction (SPE) followed by reaction with a precipitating agent and subsequent turbidimetric evaluation.
Major obstacle in this development topic regarding residual scale inhibitor detection methodologies relay on the matrix interference due to contaminants and the usual high salinity in samples. In fact, SPE allowed the removal of these interferents and, also, made feasible the analyte pre-concentration. The reagent Hyamine 1622 was employed due to its ability to effectively precipitate anionic surfactants, generating detectable turbidity. For this, the methodology was optimized considering sample percolation and desorption volumes, pH, time and temperature related to the complexation between the inhibitor and Hyamine 1622, being then successful in quantifying the polymeric scale inhibitor (usually employed in squeeze treatment) in residual levels with adequate linearity. In addition, it was found that the possible presence of iron (due to corrosive processes) does not compromise the analy sis, which is highly desirable. Further evaluation was also carried out with synthetic brine samples (representative of the field conditions), showing similar behavior that is found for produced water, indicating that the procedure is efficient in removing interferents.
Each brazilian scenario offers physicochemical particularities due to the inherent well characteristics, which are based both on the matrix and the active polymeric compounds from the squeeze treatment. Therefore, each development and optimization method will depend on these variables, but the present initiative demonstrates not only the viability of the analytical and operational approach, but also the potential to standardize analyzes in an offshore environment.
