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The long-term behavior of radium associated with oil-field brines is not well known. A production facility located on an interdistributary delta plain in southern Louisiana discharged brine into an estuarine marsh from 1957 until early 1983, when the facility began injecting produced water into an injection well. Produced water at this facility has elevated radium concentrations.
A study of the marsh soil adjacent to the facility in 1980 reported elevated radium concentrations. The 1980 sample sites were resampled for this study and analyzed for radium. Concentrations are now below natural background levels. The largest reductions were observed in samples that previously reported the highest values. The mineralogical host of the radium appears to be a solid barium sulfate (BaSO4) phase, in contrast to previous reports of radium being adsorbed on clay minerals.
The study area was severely impacted by Hurricane Katrina in 2005, lying directly in the path of the eye. Some of the production facilities that handle naturally occurring radioactive material (NORM) were destroyed, and spills of both oil and formation water occurred.
Study results indicate that remediation of the marsh is occurring naturally in a time frame as short as two decades. The long-term effects of discharging oil-field brines with NORM in an area with active sedimentation appears to be minimal.
Matthew W. Totten Sr. is an associate professor of geology at Kansas State University, after serving on the faculty at the University of New Orleans from 1992 to 2005. He received his B.S. degree in geology from the University of Kansas (1977) and his M.S. degree (1979) and his Ph.D. (1992) from the University of Oklahoma. His primary research interests include the mineralogy and chemistry of fine-grained sedimentary rocks.
Mark Hanan has degrees in geology from the University of Kansas (B.S. degree, 1978) and the University of New Orleans (M.S. degree, 1981, and Ph.D., 1998). Prior to his current position as unitization geologist with the Minerals Management Service, he was a production, staff, and joint-interest geologist for Exxon. He is an adjunct professor of earth and environmental sciences at the University of New Orleans.
Sheri Simpson has worked for Chevron since 2001 as an inorganic geochemist and primarily works as an interpreter of produced water data for enhanced recovery, scale and corrosion control, and disposal issues. She received her B.S. degree in biology from the University of New Orleans in 1998 and her M.S. degree in geology in 2000.