Analysis of Measured and Modeled Formaldehyde over the Permian Basin

Abstract:

The development of horizontal drilling and hydraulic fracturing has led to a steep increase in the U.S. production of natural gas and crude oil from shale formations since the mid 2000s. Associated with this industrial activity are emissions of ground-level ozone precursors such as nitrogen oxides and VOCs. Here we use formaldehyde (HCHO) observations from the TROPOMI satellite instrument and simulated HCHO from WRF-Chem to study if HCHO can be used as a proxy for VOC emissions. Correlation of TROPOMI HCHO with production data shows a positive slope between April and September, as increases in photochemical activity yield HCHO amounts that are significantly discernable from space. We observe no correlation in winter indicating a smaller contribution of direct emissions sources of HCHO. To investigate if and how much of the observed HCHO is the product of oil and gas related VOC emissions versus the product of other VOC sources, e.g. biogenic emissions, we compare TROPOMI HCHO with WRF-Chem simulations. Separate model runs are used to test the model sensitivity to isoprene emissions inventories as well as to NOx and VOC emissions constrained by the Fuel-based Oil and Gas Emission Inventory. Finally, we are studying data from 2020 to look at the implications of the COVID-19 lockdowns and the downturn in drilling activity on oil and gas emissions.