Real-time surrogate analysis for potential oil and gas contamination of drinking water resources

Abstract

Public concerns related to the fast-growing shale oil and gas industry have increased during recent years. The major concern regarding shale gas production is the potential of fracturing fluids being injected into the well or produced fluids flowing out of the well to contaminate drinking water resources such as surface water and groundwater. Fracturing fluids contain high total dissolved solids (TDS); thus, changes in TDS concentrations in groundwater might indicate influences of fracturing fluids. An increase of methane concentrations in groundwater could also potentially be due to hydraulic fracturing activities. To understand the possible contamination of groundwater by fracturing activities, real-time groundwater monitoring is being implemented in the Denver-Julesburg basin of northeast Colorado. A strategy of monitoring of surrogate parameters was chosen instead of measuring potential contaminants directly, an approach that is not cost effective or operationally practical. Contaminant surrogates of TDS and dissolved methane were proposed in this study, and were tested for correlation and data distribution with laboratory experiments. Correlations between TDS and electrical conductivity (EC), and between methane contamination and oxidation-reduction potential (ORP) were strong at low concentrations of contaminants (1 mg/L TDS and 0.3 mg/L CH 4 ). Dissolved oxygen (DO) was only an effective surrogate at higher methane concentrations (C2.5 mg/L). The results indicated that EC and ORP are effective surrogates for detecting concentration changes of TDS and methane, respectively, and that a strategy of monitoring for easy to measure parameters can be effective detecting real-time, anomalous behavior relative to a predetermined baseline.

New Tracers Identify Hydraulic Fracturing Fluids and Accidental Releases from Oil and Gas Operations

“…We evaluated the potential of the new proposed geochemical tracers to universally identify HFFF in the environment using previously published B/Cl data from the Marcellus and other unconventional basins. ,,,− The data show that B/Cl ratios in HFFF are higher throughout the Marcellus Basin compared to the ratios in PW from conventional oil and gas reservoirs in the Appalachian Basin (Figure ). In other unconventional plays (e.g., Bakken, Woodford) (Figure ) reported B/Cl ratios were also higher (Figure ). , Importantly, our data from HFFF from the Fayetteville Shale show similar B/Cl and Li/Cl ratios and corresponding δ 11 B (26–33‰) and δ 7 Li (5–10‰) ranges (Figure ) overlap those observed in Marcellus HFFF. Source-rock formations targeted for HVHF typically contain marine shales that have been buried and heated to elevated pressures and temperatures (>100 °C) associated with the formation of hydrocarbons.…”

“…In other unconventional plays (e.g., Bakken, Woodford) (Figure 1) reported B/Cl ratios were also higher (Figure 6). 32,35 Importantly, our data from HFFF from the Fayetteville Shale show similar B/Cl and Li/Cl ratios and corresponding δ 11 B (26−33‰) 18 and δ 7 Li (5−10‰) ranges (Figure 5) overlap those observed in Marcellus HFFF. Source-rock formations targeted for HVHF typically contain marine shales that have been buried and heated to elevated pressures and temperatures (>100 °C) associated with the formation of hydrocarbons.…”

Setting the baseline for shale gas – Establishing effective sentinels for water quality impacts of unconventional hydrocarbon development

“…Unlike for spot sampling in-situ water quality sondes are subject to damage and vandalism and must be maintained and calibrated in-situ. Son et al (2015Son et al ( , 2018 have proposed the use of in-situ water quality sondes down borehole in areas of active hydraulic fracturing in northern Colorado to monitor for pollution events. The problem of interpretation would be equally true for high frequency as for low frequency data obtained from spot sampling, i.e.…”

Evaluation of the effect of copper on the restart of a novel combined two‐stage anaerobic digester

“…Positive ORP values indicate the presence of dissolved methane (Son & Carlson, 2015). Thus, MUASB effluent might contain dissolved methane.…”