Optimized Geochemical Modeling of Produced Fluids Provides Important Insight into NORM-Related Issues

Although the formation of Naturally Occurring Radioactive Material (NORM) associated with oil and gas-related produced fluids is a widespread phenomenon, the unanticipated discovery of NORM within tubulars (pipes, pumps, and tanks) and within former brine handling facilities can be a disconcerting and problematic event. To aid clients in predicting NORM formation and likely locations of its formation, we have developed an optimized geochemical modeling approach. The modeling approach allows geological and geochemical insight into the fundamentals of produced fluid chemistry and NORM formation. Using the established knowledge associated with NORM constituent formation, and combined with actual or estimated produced fluid geochemistry in terms of salinity, temperature, and individual constituent composition, the modeling approach estimates geochemical changes induced by extraction and fluid handling processes. Specifically, the effects of solution cooling during extraction are modeled to assess the potential for barite (barium sulfate [BaSO₄]) precipitate formation and the co-precipitation of radium using a specially developed thermodynamic database. Combined with the use of Pitzer activity, coefficient-based modeling estimates as to the potential mass and radioactivity of the NORM can be made as well as associated non-NORM-bearing scale potential. The above individual components of this geochemical modeling process and the value of the insight offered will be detailed within this paper.