Produced Water Radioactivity

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Logan Franklin
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1 Produced Water Radioactivity Regulation Lax as Gas Wells Tainted Water Hits Rivers, Ian Urbina, NYT, 2/26/11 Tad Patzek, (Petroleum), UT Austin February 28, 2011, PGE

2 Summary of Conclusions The total alpha measurements should reflect mostly radon (Rn) gas, dissolved in produced frac water (where available, other α-radioactivity was subtracted) The radium Ra and Ra isotopes have T 1/2 of 5.79 and 1,602 years, respectively The uranium U and U isotopes have T 1/2 of 4.5 and 0.7 billion years, respectively The radon Rn and Rn isotopes have T 1/2 of 55.6 sec and 3.82 days, respectively p.1/18

3 Summary of Conclusions Chemical properties of radium mostly resemble those of barium, its high concentration is due to the ion exchange of formation minerals and water with the barium-rich drilling mud(?) Airborne (not water-dissolved) radon is responsible for the majority of the public exposure to ionizing radiation; it is often the single largest contributor to an individual s background radiation dose Airborne radon is the second most frequent cause of lung cancer, after cigarette smoking, causing 21,000 lung cancer deaths per year in the United States p.2/18

4 Radioactive decay chains Image source: Wikipedia p.3/18

5 Leaching of radium Radium is less strongly sorbed to the silicate surface than its thorium or uranium parents and has the potential for desorption from the aquifer matrix to groundwater when the Th-230 decays Potential exists for the newly formed Ra-226 ions to be physically ejected into solution from the rock matrix upon their creation (alpha recoil) The bond to the matrix can be weakened by the emission energy, increasing the potential for the Ra-226 to leach to groundwater because of increased competition for cation exchange sites on the rock matrix from other ions in solution p.4/18

6 MCLs and scales The Maximum Contaminant Levels are: Radon: 300 picocurie/l (pci/l) = 0.3 nanocurie/l (nci/l), or 300 radioactive decays per second in 27 L of water. The Alternative MCL (AMCL) is 4,000 pci/l Radium: 5 pci/l Uranium 5 pci/l Radioactivities were scaled as follows: Total α and Rn from 0 to 45 nci/l Ra-226 and 228 from 0 to 18 nci/l U-235 and 238 from 0 to 500 pci/l p.5/18

7 Totalα-radiation Well rank Total α particle radioactivity, nci/l p.6/18

8 Alpha-radiation is multifractal The measured α-emissions were ranked with respect to level: Rank 1 is given to the highest emission in the sample The ranked distribution of α-emission levels plots as a parabola on a log-log scale This means that the α-emissions are a power function of rank, whose negative exponent decreases with the increasing rank This means that at any emission level there is increasingly more samples with smaller emissions Such a distribution is multifractal: there is no physically meaningful mean and standard deviation p.7/18

9 Totalα-radiation Total α, pci/l Source rank p.8/18

10 Radon or totalα-radiation Well rank Radon radioactivity, nci/l p.9/18

11 Radon or totalα-radiation AMCL Radon α, pci/l MCL Source rank p.10/18

12 Ra-226α-radiation 40 Well rank Radium 226 radioactivity, nci/l p.11/18

13 Ra-226α-radiation Radium 226 α, pci/l MCL Source rank p.12/18

14 Ra-228α-radiation 40 Well rank Radium 228 radioactivity, nci/l p.13/18

15 Ra-228α-radiation Radium 228 α, pci/l MCL Source rank p.14/18

16 U-235α-radiation Well rank Uranium 235 radioactivity, pci/l p.15/18

17 U-235α-radiation Uranium 235 α, pci/l MCL Source rank p.16/18

18 U-238α-radiation Well rank Uranium 238 radioactivity, pci/l p.17/18

19 U-238α-radiation Uranium 238 α, pci/l MCL Source rank p.18/18

Sampling Instead of Source Blending: A Potential Inexpensive Path to Gross Alpha MCL Compliance

Sampling Instead of Source Blending: A Potential Inexpensive Path to Gross Alpha MCL Compliance Jeff Stovall, Ph.D., P.E., Carollo Engineers and Geri Wellborn, Norman Utilities Authority 2017 Southwest