Influence of High Total Dissolved Solids Concentration and Ionic Composition on γspectroscopy Radium Measurements of Oil and Gas-Produced Water

Moses A. Ajemigbitse, Travis L. Tasker, Fred S. Cannon, Nathaniel R. Warner

Research output: Contribution to journalArticle

1 Scopus citations

Abstract

Radium measurements in high total dissolved solids (TDS) fluids from oil and gas extraction can have unfavorable precision and accuracy, in part because these high-level impurities incur attenuation. γspectroscopy is often recommended for determining radium activities in these fluids, but even this method can produce a range of reported activities for the same sample. To reduce measurement duration and to maintain or improve accuracy, we propose a method to rapidly assess both 226Ra and 228Ra and to account for the self-attenuation of γrays in high-TDS oil and gas fluids when they are monitored by a well detector. In this work, comparisons between a NaCl-only and a multi-cation-chloride synthetic brine spiked with known amounts of 226Ra and 228Ra indicated that both the TDS concentration and the type of TDS (i.e., Na only vs Na-Mg-Ba-Ca-Sr) influenced self-attenuation in well-detector γspectroscopy, thus highlighting the need to correct for this TDS-influenced self-attenuation. Radium activities can be underestimated if the correction is not applied. For instance, 226Ra activities could be â¼40% lower in a sample when measured directly at the 186 keV energy level if the attenuation of the high TDS of the fluid is not considered. We also showed that using a NaCl-only brine to match the matrix of high-TDS oil and gas brines is inadequate to produce accurate measurements, rather, the full set of cations should be included.

Original languageEnglish (US)
Pages (from-to)10295-10302
Number of pages8
JournalEnvironmental Science and Technology
Volume53
Issue number17
DOIs
StatePublished - Sep 3 2019

All Science Journal Classification (ASJC) codes

  • Chemistry(all)
  • Environmental Chemistry

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