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Towards a Transparent Framework for Risk-based Evaluation of Treated Produced Water in the Permian
Citation:
Davis, C., J. Butler, A. Redman, C. Danforth, S. Thimons, M. Jahne, AND P. Xu. Towards a Transparent Framework for Risk-based Evaluation of Treated Produced Water in the Permian. Presented at SETAC North America 44th Annual Meeting, Louisville, KY, November 12 - 16, 2023.
Impact/Purpose:
There is growing interest in promoting the treatment and beneficial re-use of production water from onshore oil & gas operations. A significant challenge to re-use strategies is the variable and complex chemical composition of produced waters. Produced waters (PW) may come from multiple wells, they often change in composition as the well ages, and may include intentionally added chemicals (e.g., biocides, solubilizing agents, lubricants, etc…), geogenic contaminants (petroleum hydrocarbons, NORM), as well as high mineral and solids concentrations (TDS, major ions). As a result, partial or complete treatment of produced waters may be required to facilitate various beneficial re-use scenarios. As part of the assessment of suitability for PW re-use, a quantitative, risk-based evaluation which includes potential for environmental and human health risks should be included. To date, a harmonized quantitative risk assessment approach for evaluating untreated and treated produced water has not been developed. A quantitative framework is thus required which can address (1) compositional variability (e.g., organics, ionizables, and metals/mineral chemistries), (2) exposure considerations, and which can adequately and reliably estimate hazard thresholds (e.g., PNECs and DNELs), particularly when experimental data for many constituents is not readily available. The purpose of this work is to outline the compositional, exposure, effects, and methodological needs to perform robust, reliable risk assessment for PW and its constituents. This framework emphasizes the utilization (with appropriate modification) of existing exposure modeling (e.g., EUSES and TICKET-UWM for organics and metals, respectively), hazard estimation (e.g., TSM, toxic unit addition), emissions quantification (e.g., use maps and specific environmental release categories (SpERCs) approaches to leverage existing methodology & institutional knowledge. Ultimately, an objective of the scientific community in this space should be an engaged and trained community of practice centered around harmonized approaches and a user-friendly, freely available risk assessment toolbox.
Description:
There is growing interest in promoting the treatment and beneficial re-use of production water from onshore oil & gas operations. A significant challenge to re-use strategies is the variable and complex chemical composition of produced waters. Produced waters (PW) may come from multiple wells, they often change in composition as the well ages, and may include intentionally added chemicals (e.g., biocides, solubilizing agents, lubricants, etc…), geogenic contaminants (petroleum hydrocarbons, NORM), as well as high mineral and solids concentrations (TDS, major ions). As a result, partial or complete treatment of produced waters may be required to facilitate various beneficial re-use scenarios. As part of the assessment of suitability for PW re-use, a quantitative, risk-based evaluation which includes potential for environmental and human health risks should be included. To date, a harmonized quantitative risk assessment approach for evaluating untreated and treated produced water has not been developed. A quantitative framework is thus required which can address (1) compositional variability (e.g., organics, ionizables, and metals/mineral chemistries), (2) exposure considerations, and which can adequately and reliably estimate hazard thresholds (e.g., PNECs and DNELs), particularly when experimental data for many constituents is not readily available. The purpose of this work is to outline the compositional, exposure, effects, and methodological needs to perform robust, reliable risk assessment for PW and its constituents. This framework emphasizes the utilization (with appropriate modification) of existing exposure modeling (e.g., EUSES and TICKET-UWM for organics and metals, respectively), hazard estimation (e.g., TSM, toxic unit addition), emissions quantification (e.g., use maps and specific environmental release categories (SpERCs) approaches to leverage existing methodology & institutional knowledge. Ultimately, an objective of the scientific community in this space should be an engaged and trained community of practice centered around harmonized approaches and a user-friendly, freely available risk assessment toolbox.