Predicting emissions from oil and gas operations in the Uinta Basin, Utah

ABSTRACT

In this study, emissions of ozone precursors from oil and gas operations in Utah’s Uinta Basin are predicted (with uncertainty estimates) from 2015–2019 using a Monte-Carlo model of (a) drilling and production activity, and (b) emission factors. Cross-validation tests against actual drilling and production data from 2010–2014 show that the model can accurately predict both types of activities, returning median results that are within 5% of actual values for drilling, 0.1% for oil production, and 4% for gas production. A variety of one-time (drilling) and ongoing (oil and gas production) emission factors for greenhouse gases, methane, and volatile organic compounds (VOCs) are applied to the predicted oil and gas operations. Based on the range of emission factor values reported in the literature, emissions from well completions are the most significant source of emissions, followed by gas transmission and production. We estimate that the annual average VOC emissions rate for the oil and gas industry over the 2010–2015 time period was 44.2E+06 (mean) ± 12.8E+06 (standard deviation) kg VOCs per year (with all applicable emissions reductions). On the same basis, over the 2015–2019 period annual average VOC emissions from oil and gas operations are expected to drop 45% to 24.2E+06 ± 3.43E+06 kg VOCs per year, due to decreases in drilling activity and tighter emission standards.

Implications: This study improves upon previous methods for estimating emissions of ozone precursors from oil and gas operations in Utah’s Uinta Basin by tracking one-time and ongoing emission events on a well-by-well basis. The proposed method has proven highly accurate at predicting drilling and production activity and includes uncertainty estimates to describe the range of potential emissions inventory outcomes. If similar input data are available in other oil and gas producing regions, then the method developed here could be applied to those regions as well.

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Additional information

Notes on contributors

Jonathan Wilkey

Jonathan Wilkey is a chemical engineering graduate student at the University of Utah.

Kerry Kelly

Kerry Kelly is an assistant professor in chemical engineering at the University of Utah.

Isabel Cristina Jaramillo

Isabel Cristina Jaramillo is a research associate at the Institute for Clean and Secure Energy at the University of Utah.

Jennifer Spinti

Jennifer Spinti is a research associate professor in chemical engineering at the University of Utah.

Terry Ring

Terry Ring is a professor in chemical engineering at the University of Utah.

Michael Hogue

Michael Hogue is a senior research statistician at the Kem C. Gardner Policy Institute at the University of Utah.

Donatella Pasqualini

Donatella Pasqualini is a physicist in the Computational Earth Science Group (Integrated Geosystem team) in the Earth and Environmental Sciences Division at Los Alamos National Laboratory.