Measurement of 222Rn Flux, 222Rn Emanation, and 226,228Ra Concentration from Injection Well Pipe Scale

Abstract

222Rn flux (Bq s(-1)) was measured from the ends of twenty sections of produced water injection tubing (pipe) containing barite scale contaminated with naturally occurring radioactive material. Exposure measurements near the pipes were as high as 77.4 nC kg(-1)h(-1) (300 microR h(-1)). Flux measurements were accomplished by first purging the pipes with dry nitrogen and then collecting the outflow (nitrogen and radon) on charcoal columns affixed to the end of the pipe for 66 hours. As determined in this manner, 222Rn flux from the ends of the pipe ranged from 0.017 to 0.10 Bq s(-1) (0.46 to 2.7 pCi s(-1)). Following the radon flux measurements, pipe scale was removed and a representative sample was taken for 226Ra and 228Ra concentration measurements and determination of 222Rn emanation fractions (the fraction of the total radon contained in a material that is released from the material and free to migrate). The samples were also analyzed for gross mineral content. Emanation fraction measurements for 222Rn ranged from 0.020 to 0.063, while 226Ra concentrations ranged from 15.7 to 102 Bq g(-1) (424 to 2,760 pCi g(-1)). Barite was the predominate mineral in 17 of the 20 scale samples collected. Much of the previous work dealing with radon emanation fraction measurements has involved uranium mill tailings. Compared to mill tailings and natural soils which have emanation fractions that typically range from 0.1 to 0.3, the emanation fractions measured for these NORM scales are substantially lower.

Radionuclides, trace elements, and radium residence in phosphogypsum of Jordan

“…More studies are needed to determine if fine-grained, Ra-bearing barite has a lower Rn-emanation fraction than typical values of 0.12-0.20 reported for grains of PG (Roessler et al 1979b;Rutherford et al 1995). Coarser grains of Ra-bearing barite scale from oil field pipes had Rn emanation fractions of 0.02-0.063 (Rood et al 1998). …”

User's manual for RESRAD-BUILD version 3.

“…Additional information on the radon emanation fraction can be found in documents by Tanner (1964Tanner ( , 1980; Barretto et al (1972); Pensko et al (1972);Wilkening (1974);Periera (1980);Ingersoll (1983); Schery et al (1984); Damkjaer and Korsbech (1985); Van der Lugt and Scholten (1985); Schery and Whittlestone (1989); Rogers and Nielson (1991); Markkanen and Arvela (1992);and Rood et al (1998).…”

Potential radiological doses associated with the disposal of petroleum industry NORM via landspreading. Final report, September 1998

“…0.25). A recent study measured the h -2 2 2 emanation fraction in scale; measurements ranged from 0.02 to 0.06 (Rood and Kendrick 1996).6 At these low levels, if NORM scale was mixed into a soil layer, the rate of radon emanation f o m the soil would be well below the 20 pCi/m2/s standard contained in some state regulations (see Section 1.2.2).…”