Hydraulic fracturing is the propagation of fractures in a rock layer by pressurized fluid. Induced hydraulic fracturing or hydrofracking, commonly known as fracking, is a technique used to release petroleum, natural gas (including shale gas, tight gas and coal seam gas), or other substances for extraction, particularly from unconventional reservoirs.[1] Radionuclides are associated with fracking in two main ways. Injection of man-made radioactive tracers, along with the other substances in hydraulic-fracturing fluid, is often used to determine the injection profile and location of fractures created by fracking.[2] In addition, fracking releases naturally occurring heavy metals and radioactive materials from shale deposits, and these substances return to the surface with flowback, also referred to as wastewater.[3]

Naturally occurring radionuclides

There are naturally occurring radioactive material (e.g., radium and radon) in shale deposits.[4] Hydraulic fracturing can dislodge naturally occurring heavy metals and radioactive materials from shale deposits, and these substances return to the surface with flowback, also referred to as wastewater or brine.[4][5][6][7] These naturally occurring radionuclides are of more concern than some man-made radionuclides used in fracture monitoring because of their long half lives. Radium-226 is a product of Uranium-238 decay, and is the longest-lived isotope of radium with a half-life of 1601 years; next longest is Radium-228, a product of Thorium-232 breakdown, with a half-life of 5.75 years.[8] Radon (Rn) is a naturally occurring product of the decay of uranium or thorium. Its most stable isotope, Radon-222, has a half-life of 3.8 days. Strontium is also naturally occurring and may be dislodged by the process.[5] Higher levels of Lead-210, the decay product of Radon-222, have been found on the airborne particulate matters that are collected downwind of wells completed with hydraulic fracturing.[9]

Injected radionuclides

Injection of radioactive tracers, along with the other substances in hydraulic-fracturing fluid, is often used to determine the injection profile and location of fractures created by hydraulic fracturing.[2] Patents describe in detail how several tracers are typically used in the same well. Wells are hydraulically fractured in different stages.[10] Tracers with different half-lives are used for each stage.[10][11] Their half-lives range from 40.2 hours (Lanthanum-140) to 28.90 years (Strontium-90).[12] Amounts per injection of radionuclide are listed in the US Nuclear Regulatory Commission (NRC) guidelines.[13] The NRC guidelines also list a wide range or radioactive materials in solid, liquid and gaseous forms that are used as field flood or enhanced oil and gas recovery study applications tracers used in single and multiple wells.[13] According to the NRC, some of the most commonly used include Antimony-124, Bromine-82, Iodine-125, Iodine-131, Iridium-192, and Scandium-46.[13] A 2003 publication by the International Atomic Energy Agency (IAEA) provides a detailed description of tracer use, confirms the frequent use of most of the tracers above, and says that Manganese-56, Sodium-24, Technetium-m, Silver-m, Argon-41, and Xenon-133 are also used extensively because they are easily identified and measured.[14] Other potentially suitable tracers are named in various patents.[10][11][15] In terms of quantities used, the NRC gives the following examples: Iodine-131, gas form, 100 millicuries total, not to exceed 20 millicuries per injection; Iodine-131, liquid form, 50 millicuries total, not to exceed 10 millicuries per injection; Iridium-192, "Labeled" frac sand, 200 millicuries total, not to exceed 15 millicuries per injection; Silver-110m, liquid form, 200 millicuries total, not to exceed 20 millicuries per injection.[16]

Other gamma-emitting tracer isotopes used are Antimony-121, Antimony-122, Antimony-123, Antimony-125, Antimony-126, Antimony-127, Carbon-14, Chromium-51, Cobalt-57, Cobalt-58, Cobalt-60, Gold-198, Iodine-127, Iodine-128, Iodine-129, Iodine-130, Iron-59, Krypton-85, Lanthanum-140, Potassium-39 (activated to Potassium-40), Potassium-41 (activated to Potassium-42), Potassium-43, Rubidium-86, Scandium-45, Scandium-47, Scandium-48, Silver-110, Sodium-22, Strontium-85, Strontium-90, Tritium, Zinc-65, and Zirconium-95.[10][11][12][13][15]

Environmental impact

Concerns have been expressed that both naturally occurring radionuclides and radioactive tracers may return to the surface with flowback and during blow outs.[17][18] Wastewater from the wells is released into rivers, injected into wells, and evaporated from ponds.[4] The Times reported that studies by the United States Environmental Protection Agency and a confidential study by the drilling industry concluded that radioactivity in drilling waste cannot be fully diluted in rivers and other waterways.[19] Recycling the wastewater has been proposed as a solution but has its limitations.[20] The New York Times has reported on radium and gross alpha radiation levels in wastewater (also called flowback) from natural gas wells. It collected data from more than 200 natural gas wells in Pennsylvania. The New York Times has compiled a map of these wells and their wastewater contamination levels.[4][6][21]

Political, governmental, and industry pressures have prevented the United States Environmental Protection Agency (EPA) from studying risks associated with radionuclides[22] or other chemicals in hydraulic fracturing fluids in wastewater,[23] source water, and drinking water.[22][24][25][26][27] The scope of the EPA Hydraulic Fracturing Draft Study Plan was narrowed to exclude them.[22][26][28]

Health impact

As radon decays, it produces radioactive decay products. If the contaminated dust of these "radon daughters" are inhaled, they can lodge in the lungs and increase the risk of developing lung cancer.[29] Iodine in food is absorbed by the body and preferentially concentrated in the thyroid where it is needed for the functioning of that gland. When Iodine-131 is present in high levels in the environment from hydraulic fracturing flowback and blowouts, it can be absorbed through contaminated food and water, and will also accumulate in the thyroid. As it decays, it may cause damage to the thyroid. The primary risk from exposure to high levels of iodine-131 is the chance occurrence of radiogenic thyroid cancer in later life. Other risks include the possibility of non-cancerous growths and thyroiditis.[30][31] The level of radiation in hydraulic fracturing wastewater has been measured to be as high as 18,035 pCi/L,[6] thousands of times the maximum allowed by the federal standard for drinking water,[4][6] and there are concerns about radiation exposure during spills and blowouts.[17][18] Long term exposure to low level radiation is associated with stochastic[32] health effects; the greater the exposure, the more likely the health effects are to occur.[32] A group of doctors from the United States have called for a moratorium on hydraulic fracturing until health effects are more thoroughly studied.[33][34]

Regulation

The US Nuclear Regulatory Commission (NRC) and approved state agencies regulate the use of injected radionuclides in hydraulic fracturing in the United States.[13] Federal and state regulators do not require sewage treatment plants that accept drilling waste to test for radioactivity. In Pennsylvania, where the hydraulic fracturing drilling boom began in 2008, most drinking-water intake plants downstream from those sewage treatment plants have not tested for radioactivity since before 2006.[35] The EPA has asked the Pennsylvania Department of Environmental Protection to require community water systems in certain locations, and centralized wastewater treatment facilities to conduct testing for radionuclides.[36][37] Safe drinking water standards have not yet been established to account for radioactivity levels of hydraulic fracturing waste water,[4] and although water suppliers are required to inform citizens of radon and other radionuclides levels in their water, this doesn't always happen.[38] Radioactive tracers are not yet listed on FracFocus,[39] a website indicating chemical composition of fracking fluid of individual wells, but federal and state nuclear regulatory agencies keep records of their use.[13]

References

  1. ↑ Charlez, Philippe A. (1997). Rock Mechanics: Petroleum Applications. Paris: Editions Technip. p. 239. ISBN 978-2-7108-0584-7. Retrieved 2012-05-14.
  2. 1 2 Reis, John C. (1976). Environmental Control in Petroleum Engineering. Gulf Professional Publishers.
  3. ↑ "Iodine 131 Found in Philadelphia's Drinking Water" (Press release). Bucks County Water & Sewer Authority. 12 April 2011. Retrieved 11 May 2012. In response to these results, PWD is working with the EPA and DEP and taking the following actions: Developing a Joint PADEP, EPA, PWD Action Plan for all Radionuclides; Initiating a focused sampling program for Iodine; Developing an aggressive track down program with EPA and DEP to identify the potential sources of Iodine 131 in our source waters.
  4. 1 2 3 4 5 6 Urbina, Ian (26 February 2011). "Regulation Lax as Gas Wells' Tainted Water Hits Rivers". The New York Times. Retrieved 22 February 2012. The level of radioactivity in the wastewater has sometimes been hundreds or even thousands of times the maximum allowed by the federal standard for drinking water.
  5. 1 2 Linda Marsa (1 August 2011). "Fracking Nation. Environmental concerns over a controversial mining method could put America's largest reservoirs of clean-burning natural gas beyond reach. Is there a better way to drill?". Environment / Pollution. Discover Magazine. Archived from the original on 27 March 2015. Retrieved 7 April 2015.
  6. 1 2 3 4 White, Jeremy; Park, Haeyoun; Urbina, Ian; Palmer, Griff (26 February 2011). "Toxic Contamination From Natural Gas Wells". The New York Times.
  7. ↑ Nobel, Justin (2021-01-21). "America's Radioactive Secret". Rolling Stone. Retrieved 2022-07-06.
  8. ↑ "Chart Nuclides by the National Nuclear Data Center (NNDC)". Retrieved 2009-08-01.
  9. ↑
    Deziel, Nicole C. (2021). "Invited Perspective: Oil and Gas Development and Adverse Birth Outcomes: What More Do We Need to Know?". Environmental Health Perspectives (ehp). Environmental Health Perspectives (ehp). 129 (7). doi:10.1289/ehp9715. ISSN 0091-6765. PMC 8312483. PMID 34287014. S2CID 236156369.
    This review cites this research.
    Li, Longxiang; Blomberg, Annelise J.; Spengler, John D.; Coull, Brent A.; Schwartz, Joel D.; Koutrakis, Petros (2020). "Unconventional oil and gas development and ambient particle radioactivity". Nature Communications. Nature Portfolio. 11 (1). doi:10.1038/s41467-020-18226-w. ISSN 2041-1723. PMC 7553919. S2CID 222353253.
  10. 1 2 3 4 http://ip.com/patent/US5635712 Scott III, George L. (03-June-1997) US Patent No. 5635712: Method for monitoring the hydraulic fracturing of a subterranean formation. US Patent Publications.
  11. 1 2 3 http://ip.com/patent/US5441110 Scott III, George L. (15-Aug-1995) US Patent No. US5441110: System and method for monitoring fracture growth during hydraulic fracture treatment. US Patent Publications.
  12. 1 2 https://archive.today/20121209065049/http://ip.com/patent/ep0340956a1 Gadeken, Larry L., Halliburton Company (08-Nov-1989). Radioactive well logging method.
  13. 1 2 3 4 5 6 Jack E. Whitten; Steven R. Courtemanche; Andrea R. Jones; Richard E. Penrod; David B. Fogl (June 2000). "Consolidated Guidance About Materials Licenses: Program-Specific Guidance About Well Logging, Tracer, and Field Flood Study Licenses". US Nuclear Regulatory Commission. NUREG-1556, Volume 14. Retrieved 19 April 2012. labeled Frac Sand ... Sc-46, Br-82, Ag-110m, Sb-124, Ir-192
  14. ↑ Radiation Protection and the Management of Radioactive Waste in the Oil and Gas Industry (PDF) (Report). International Atomic Energy Agency. 2003. pp. 39–40. Retrieved 20 May 2012. Beta emitters including H-3 and C-14 may be used when it is feasible to use sampling techniques to detect the presence of the radiotracer or when changes in activity concentration can be used as indicators of the properties of interest in the system. Gamma emitters, such as Sc-46, La-140, Mn-56, Na-24, Sb-124, Ir-192, Tc-m, I-131, Ag-m, Ar-41, and Xe-133 are used extensively because of the ease with which they can be identified and measured ... In order to aid the detection of any spillage of solutions of the 'soft' beta emitters, they are sometimes spiked with a short half-life gamma emitter such as Br-82...
  15. 1 2 http://ip.com/patent/US4415805 Fertl; Walter H. (15-Nov-1983) US Patent No. US4415805: Method and apparatus for evaluating multiple stage fracturing or earth formations surrounding a borehole. US Patent Publications.
  16. ↑ "Consolidated Guidance About Materials Licenses: Program-Specific Guidance About Well Logging, Tracer".
  17. 1 2 Dina Murphy; Larry Huskins (8 September 2006). "Re: August 23, 2006, Accidental Release from J-67 Well on Well Pad C-67/J-67/G-67" (PDF). Concerned Citizens of Penobsquis (Letter).
  18. 1 2 ICF Incorporated, LLC (8 September 2006). "Technical Assistance for the Draft Supplemental Generic EIS: Oil, Gas and Solution Mining Regulatory Program Well Permit Issuance for Horizontal Drilling and High-Volume Hydraulic Fracturing to Develop the Marcellus Shale and Other Low Permeability Gas Reservoirs" (PDF). New York State Energy Research and Development Authority. Retrieved 7 August 2009. Radioactive tracers can be detected with wireline gamma-logging equipment in the wellbore, but their use poses additional environmental and safety concerns.
  19. ↑ "Documents: Natural Gas's Toxic Waste". The New York Times. February 26, 2011.
  20. ↑ Ian Urbina (1 March 2011). "Drilling Down: Wastewater Recycling No Cure-All in Gas Process". The New York Times. Retrieved 22 February 2012.
  21. ↑ Staff (26 February 2011). "Drilling Down: Documents: Natural Gas's Toxic Waste". The New York Times. Retrieved 23 February 2012.
  22. 1 2 3 DiCosmo, Bridget (15 May 2012). "SAB Pushes To Advise EPA To Conduct Toxicity Tests In Fracking Study". InsideEPA. US Environmental Protection Agency. (subscription required). Retrieved 2012-05-19. But some members of the chartered SAB are suggesting that the fracking panel revise its recommendation that the agency scale back its planned toxicity testing of chemicals used in the hydraulic fracturing, or fracking, process, because of the limited resources and time frame ... Chesapeake Energy supported the draft recommendation, saying that "an in-depth study of toxicity, the development of new analytical methods and tracers are not practical given the budget and schedule limitation of the study."
  23. ↑ Satterfield, John (30 June 2011). "Letter from Chesapeake Energy to EPA" (PDF). InsideEPA. US Environmental Protection Agency. Retrieved 2012-05-19. Flowback and Produced water ... Chesapeake agrees that an indepth study of toxicity, the development of new analytic methods and tracers are not practical given the budget and schedule limitations of the study ... Wastewater Treatment and Waste Disposal ... Chesapeake believes there was unjustified emphasis on the surface disposal of produced water to treatment plants in the SAB's Review ... Chesapeake disagrees with the inclusion of water distribution network corrosion and burden of analyzing for contaminants by POTW's into the study.
  24. ↑ "The Debate Over the Hydrofracking Study's Scope". The New York Times. 3 March 2011. Retrieved 1 May 2012. While environmentalists have aggressively lobbied the agency to broaden the scope of the study, industry has lobbied the agency to narrow this focus
  25. ↑ "Documents: Natural Gas's Toxic Waste". The New York Times. February 26, 2011.
  26. 1 2 Urbina, Ian (3 March 2011). "Pressure Limits Efforts to Police Drilling for Gas". The New York Times. Retrieved 23 February 2012. More than a quarter-century of efforts by some lawmakers and regulators to force the federal government to police the industry better have been thwarted, as E.P.A. studies have been repeatedly narrowed in scope and important findings have been removed
  27. ↑ Jenny Hopkinson; Bridget DiCosmo (15 May 2012). "Academies' NRC Seeks Broad Review Of Currently Ignored Fracking Risks". InsideEPA. US Environmental Protection Agency. Retrieved 2012-05-19.
  28. ↑ "Archived copy" (PDF). www.shalegas.energy.gov. Archived from the original (PDF) on 17 April 2012. Retrieved 14 January 2022.{{cite web}}: CS1 maint: archived copy as title (link)
  29. ↑ "Public Health Fact Sheet on Radon - Health and Human Services". Mass.Gov. Retrieved 2011-12-04.
  30. ↑ Rivkees, Scott A.; Sklar, Charles; Freemark, Michael (1998). "The Management of Graves' Disease in Children, with Special Emphasis on Radioiodine Treatment". Journal of Clinical Endocrinology & Metabolism. 83 (11): 3767–76. doi:10.1210/jcem.83.11.5239. PMID 9814445.
  31. ↑ Mayo clinic staff. "Radiation sickness". Mayo Clinic. Retrieved 31 March 2012.
  32. 1 2 Staff. "Radiation protection health effects". US Environmental Protection Agency. Retrieved 6 August 2012.
  33. ↑ David Wethe (19 January 2012). "Like Fracking? You'll Love 'Super Fracking'". Businessweek. Archived from the original on January 23, 2012. Retrieved 22 January 2012.
  34. ↑ Mark Drajem (11 January 2012). "Fracking Political Support Unshaken by Doctors' Call for Ban". Bloomberg. Retrieved 19 January 2012.
  35. ↑ "Regulation Lax as Gas Wells' Tainted Water Hits Rivers". The New York Times. February 26, 2011.
  36. ↑ Shawn M. Garvin (7 March 2011). "The Honorable Michael Krancer, Acting Secretary..." (PDF). United States Environmental Protection Agency (Letter). Archived from the original (PDF) on 2012-05-19. Retrieved 11 May 2012.
  37. ↑ Ian Urbina (7 March 2011). "E.P.A. Steps Up Scrutiny of Pollution in Pennsylvania Rivers". The New York Times. Retrieved 23 February 2012.
  38. ↑ Bauers, Sandy (21 July 2011). "Cancer patients' urine suspected in Wissahickon iodine-131 levels". The Philadelphia Inquirer, Carbon County Groundwater Guardians. Retrieved 25 February 2012.
  39. ↑ FracFocus
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