U.S. Department of the Interior

 

ORCID IDs

0000-0001-8493-9522

Date of this Version

2017

Citation

Environ. Sci. Technol. 2017, 51, 11625−11633

Comments

© 2017 American Chemical Society

This document is a U.S. government work and is not subject to copyright in the United States.

DOI: 10.1021/acs.est.7b03408

Abstract

We measured fluxes of methane, nonmethane hydrocarbons, and carbon dioxide from natural gas well pad soils and from nearby undisturbed soils in eastern Utah. Methane fluxes varied from less than zero to more than 38 g m−2 h−1. Fluxes from well pad soils were almost always greater than from undisturbed soils. Fluxes were greater from locations with higher concentrations of total combustible gas in soil and were inversely correlated with distance from well heads. Several lines of evidence show that the majority of emission fluxes (about 70%) were primarily due to subsurface sources of raw gas that migrated to the atmosphere, with the remainder likely caused primarily by re-emission of spilled liquid hydrocarbons. Total hydrocarbon fluxes during summer were only 39 (16, 97)% as high as during winter, likely because soil bacteria consumed the majority of hydrocarbons during summer months. We estimate that natural gas well pad soils account for 4.6 × 10−4 (1.6 × 10−4, 1.6 × 10−3)% of total emissions of hydrocarbons from the oil and gas industry in Utah’s Uinta Basin. Our undisturbed soil flux measurements were not adequate to quantify rates of natural hydrocarbon seepage in the Uinta Basin.

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