Date of Award

2022-05-01

Degree Name

Master of Science

Department

Geological Sciences

Advisor(s)

Mark Engle

Abstract

Produced waters are a voluminous byproduct of unconventional oil and gas production. Produced water volumes are primarily addressed by subsurface reinjection through saltwater disposal wells (SWDs) and reuse within the oil and gas industry. Oil and gas operators continue to evaluate and trial novel methods to improve produced water handling, and reduce freshwater use, and disposal volumes. Here, we present results for method development to quantify Critical and Valuable Elements (CVEs; defined here as the lanthanide series, high field strength elements, industrial elements and precious metals in brines. CVE concentrations in produced waters and other high-salinity waters are poorly understood and analytically challenging to quantify. Produced waters can exhibit total dissolved solids (TDS) concentrations up to and exceeding 300 g/L (dominated by Cl, Na, and Ca) and their potential as a domestic CVE source is not well documented. The U.S. is currently import dependent for >80% of its CVE supply. This project endeavors to develop a high salinity-specific method to quantify CVEs in produced waters through preconcentration using Chelex-100 ion exchange resin followed by quantification via quadrupole ICP-MS. Initial work focused on testing CVE recovery from synthetic Na-Ca-Cl brines (50, 100, 200 and 300 g/L TDS) using a Chelex-100 minicolumn. This method preconcentrates CVEs by loading ~50 mL of synthetic brine sample through a Chelex-100 resin minicolumn, removing monovalent and divalent matrix ions with 1 molar ammonium acetate, and eluting CVEs using 2 molar nitric acid. This method was tested on high salinity synthetic solutions of variable Ca/Na ratios, Na-rich (Na/Ca molar = 50) and Ca-rich (Ca/Na molar=5) and pH of 4 and 6. Results for CVE recovery in synthetic solutions will be presented and parameters found to be most effective for CVE recoveries will be employed for produced water samples analysis. Recovery data for produced waters will be compared to synthetic solution recoveries to display differences in recovery capabilities when analyzing natural brines. Improved analytical methods to quantify CVEs in waste products, such as those being developed here, are a necessary step toward understanding nontraditional domestic CVE supplies.

Language

en

Provenance

Received from ProQuest

File Size

76 p.

File Format

application/pdf

Rights Holder

Joshua Matthew Lewis

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Included in

Geochemistry Commons

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