Partitioning of naturally-occurring radionuclides (NORM) in Marcellus Shale produced fluids influenced by chemical matrix

Abstract

Naturally-occurring radioactive materials (NORM) associated with unconventional drilling produced fluids from the Marcellus Shale have raised environmental concerns. However, few investigations into the fundamental chemistry of NORM in Marcellus Shale produced fluids have been performed. Thus, we performed radiochemical experiments with Marcellus Shale produced fluids to understand the partitioning behavior of major radioelements of environmental health concern (uranium (U), thorium (Th), radium (Ra), lead (Pb), and polonium (Po)). We applied a novel radiotracer, 203Pb, to understand the behavior of trace-levels of 210Pb in these fluids. Ultrafiltration experiments indicated U, Th, and Po are particle reactive in Marcellus Shale produced fluids and Ra and Pb are soluble. Sediment partitioning experiments revealed that >99% of Ra does not adsorb to sediments in the presence of Marcellus Shale produced fluids. Further experiments indicated that although Ra adsorption is related to ionic strength, the concentrations of heavier alkaline earth metals (Ba, Sr) are stronger predictors of Ra solubility.

Investigation of produced waters radioactivity of oil and gas deposits in the Dnieper-Donets province

“…Therefore, decontamination can be carried out using methods that combine a high degree of mechanization of all technological operations, remote control of processes and reliable localization of radionuclides to a limited extent [10,11].…”

Characterization of wastes pertaining to naturally occurring radioactive materials (NORM) and the nuclear fuel cycle

“…While 72 Ga is recognized as an acceptable radionuclide for application of the isotope dilution approach, there is no commercial manufacturer and a reactor with high neutron flux irradiation capabilities is required for preparation of 72 Ga standards. 52 On the other hand, multiple manufacturers of 68 Ga generators are emerging and the availability of 68 Ga continues to 29 increase. 19 Further, the half-life of 68 Ga (68 m The use of 68 Ga as a radioisotopic tracer for the determination of stable Ga is desirable because the positron emission provides easily measured 511 keV gamma rays for direct measurement by ion chamber.…”

“…28 The problem with Ba for radiochemical separations is that Ba and Ra have very similar chemistry and often co-elute or co-precipitate during chemical separations. [28][29][30][31] The high levels of dissolved solids (in particular the high concentrations of Ba) suggested that a low-cost, rapid, practical separation of Ra from the Marcellus Shale fluids would not be possible. Given that Ra had been previously established as a key radionuclide in Marcellus Shale produced fluids and flowback, 21,32 this suggested that a single gross alpha/beta method was impractical.…”

“…We attributed this discovery to Ba interference during chemical separations, which is further discussed in ESTL and EPSI. 27,29 Lastly, and perhaps of greatest interest to us, was the apparent absence of 226 Ra decay products from the fluids. 40 Given the solubility of Pb in these fluids, 27 we expected 210 Pb to be detectable;…”

“…Due to the chemical characteristics and high organic content of the cuttings, we tailored these methods from techniques previously developed for asphalt. The method development process is described further in Eitrheim et al (2016). 41 The most interesting aspect of the study is that 226 Ra decay products were in disequilibrium with the supporting parent radionuclides.…”