CHARACTERIZATION OF FRACKING SOIL, SEDIMENT, AND WASTEWATER SAMPLES USING COMPARATIVE NEUTRON ACTIVATION ANALYSIS METHOD
Open Access
- Author:
- Kuatbek, Maksat
- Graduate Program:
- Nuclear Engineering
- Degree:
- Master of Science
- Document Type:
- Master Thesis
- Date of Defense:
- November 21, 2018
- Committee Members:
- Amanda M Johnsen, Thesis Advisor/Co-Advisor
Arthur Thompson Motta, Committee Member - Keywords:
- NAA
Hydraulic Fracturing
RSEC
PSBR - Abstract:
- The accurate multi-elemental analysis of soil, sediment, and wastewater samples is extremely important for the regulatory monitoring of oil and gas (O&G) development. This kind of analysis is typically conducted using several conventional methods, such as inductively coupled plasma optical emission spectrometry (ICP-OES) or mass spectrometry (ICP-MS). The main objective of this study was to apply the neutron activation analysis (NAA) method for qualitative and quantitative analysis of hydraulic fracturing samples and to evaluate its accuracy and applicability. In this work, seventeen solid (soil and sediment) and five liquid (wastewater) samples collected from the wellbores within Pennsylvania were characterized. The analysis was conducted at the Radiation Science and Engineering Center (RSEC) using the comparative neutron analysis method. The Montana II Soil and Buffalo River Sediment certified standard reference materials obtained from the National Institute of Standards and Technology were used as the comparators. As the result of this research, the concentration of short-, intermediate-, and long-lived isotopes of Cl, Mn, Eu, K, Na, As, La, Ca, Ba, Rb, Pa (thorium activation product), Cr, Fe, Hg, Sr, Sc, Se, Zn, and Cs elements in fracking samples were determined with an accuracy of ppm (mg/g or mg/l). The experimentally measured values then were analyzed for standard deviation and verified through a quality control check, with the exception of cesium and chromium; thus, their values were declared as non-certified. The trace element concentration values of three oil and gas wastewater samples, which were obtained by the Comparative NAA (CNAA), were compared with the most probable value (MPV) results determined via an inter-laboratory study. The MPVs were evaluated using the nonparametric statistical method on the results collected from 15 laboratories from the United States, Canada, and Germany that used different equipment and techniques for wastewater characterization. The comparison results were demonstrated in the percentage difference magnitudes that vary from 0.1% to 56.6%. There are several possible reasons that might cause such a relatively high error, as the hydride concentration remained after dehydration, the mass error of liquid samples (due to evaporation), the use of multiple vials during dehydration (sample movement), and the fragmentation of target elements (due to unfulfillment of pulverization and homogenization of dried crystals before sampling).