Emissions of nitrogen oxides (NOx) and volatile organic compounds (VOC) in the Eagle Ford Shale region could increase sharply in the coming years as development ramps up, according to a recently released study.
The Alamo Area Council of Governments, in collaboration with the Texas Commission on Environmental Quality, prepared an assessment of Eagle Ford Shale oil and gas development emissions out to 2018. According to the research, Eagle Ford production activities emitted an estimated 66 tons of NOx and 101 tons of VOCs per ozone season day in 2011. For 2012, emissions increased to 111 tons of NOx and 229 tons of VOCs per ozone season day.
To estimate emissions for 2018, calculations were based on three potential levels of development.
NOx emissions increase slightly for the "low development" scenario in 2018 (113 tons per day). NOx emissions also increase under the 2018 "moderate development" scenario (146 tons per day) and the "high development" scenario (188 tons per day). By 2018, VOC emissions are expected to increase significantly to 338 tons per ozone season day under the low scenario and to 872 tons per ozone season day under the high scenario.
The majority of NOx emissions in 2012 were emitted by drill rigs and well hydraulic pump engines (47%), according to the research. By 2018, these sources are expected to account for only 9% of the NOx emissions as engines are replaced with models that have tougher emissions standards. In contrast, compressors and midstream sources only accounted for 39% of NOx emissions in 2012, but they are expected to increase to 77% of total NOx emissions under the 2018 moderate scenario because of the significant increase in oil and gas production. The majority of VOC emissions in 2018 are from storage tanks (47%) and loading loss (32%).
More than 51% of the Eagle Ford NOx emissions are produced in four Texas counties: Webb, Dimmit, Karnes and La Salle. Eagle Ford operations in Webb County emitted 15.7 tons of NOx per ozone season day, while operations in Dimmit emitted 14.6 tons, operations in Karnes emitted 14.2 tons, and operations in La Salle emitted 12.8 tons in 2012.
Under the 2018 moderate development scenario, oil and natural gas operations are projected to emit, on an ozone season day, 26.4 tons of NOx in Webb County, 17.9 tons of NOx in Dimmit, 16.8 tons of NOx in La Salle, and 15.1 tons of NOx in Karnes.
A similar pattern occurs with VOC emissions under the 2018 moderate scenario in which ozone season daily emissions are expected to be 84.6 tons in Webb County 71.5 tons in Dimmit, 66.1 tons in La Salle and 64.8 tons in Karnes.