Trace Elements and Naturally Occurring Radioactive Material Associated with Produced Waters in Coal Seam Gas and Shale Gas Resources and Their Potential Relationship to Mineral Groups

Abstract

The focus of this study is to determine the geochemical properties of formation, produced and flowback fluids and correlate the findings to geochemical properties of different mineral groups. This analysis can be achieved by: (a) investigating the occurrence and abundance of trace elements and naturally occurring radioactive material associated with different mineral groups, (b) determining the geochemical composition of produced water associated with these compositionally different formations using a comparative study between hydrocarbon resources and individual basins, and (c) determining the mineral origin of these trace elements and NORM associated with produced water. The geochemical NORM and trace element composition associated with produced water depends on the characteristics of the original depositional environment, the composition of the source rock, post depositional genesis processes, type/grade of the hydrocarbon and the ability for these trace elements and NORM to become mobile. The USGS produced water database was used to compare the variation of geochemical properties of produced water between the various energy generating types and basins. This was achieved by developing a statistical analysis for each trace element and NORM and comparing the results between the various hydrocarbon types and basins. The results of this study illustrates; (a) that certain trace elements have an overall higher concentration within certain hydrocarbon resources, and (b) there is a correlation of trace elements concentration associated with compositionally different formation and is related to the formations unique mineralogy. The information contained in this study and studies on mechanism that impact fluid migration and well integrity will provide decision-makers the framework to develop a more detailed PWMP during the initial exploration phase that can be part of their requirements when applying to the land owners for an exploration licence.