Volatile organic compound emissions from the oil and natural gas industry in the Uintah Basin, Utah: oil and gas well pad emissions compared to ambient air composition

摘要

Emissions of volatile organic compounds (VOCs) associated with oil andnatural gas production in the Uintah Basin, Utah were measured at a groundsite in Horse Pool and from a NOAA mobile laboratory with PTR-MS instruments.The VOC compositions in the vicinity of individual gas and oil wells andother point sources such as evaporation ponds, compressor stations andinjection wells are compared to the measurements at Horse Pool. High mixingratios of aromatics, alkanes, cycloalkanes and methanol were observed forextended periods of time and for short-term spikes caused by local pointsources. The mixing ratios during the time the mobile laboratory spent on thewell pads were averaged. High mixing ratios were found close to all pointsources, but gas well pads with collection and dehydration on the well padwere clearly associated with higher mixing ratios than other wells. Thecomparison of the VOC composition of the emissions from the oil and naturalgas well pads showed that gas well pads without dehydration on the well padcompared well with the majority of the data at Horse Pool, and that oil wellpads compared well with the rest of the ground site data. Oil well pads onaverage emit heavier compounds than gas well pads. The mobile laboratorymeasurements confirm the results from an emissions inventory: the main VOCsource categories from individual point sources are dehydrators, oil andcondensate tank flashing and pneumatic devices and pumps. Raw natural gas isemitted from the pneumatic devices and pumps and heavier VOC mixes from thetank flashings.