Flaring in two Texas shale areas: Comparison of bottom-up with top-down volume estimates for 2012 to 2015.

Since advances in horizontal drilling and hydraulic fracturing technologies have opened oil and gas development in previously unreachable areas, air pollution emissions have increased from the burning (i.e., flaring) or releasing (i.e., venting) of natural gas at oil and gas extraction sites. While venting and flaring is a growing concern, accounting of how much gas is vented and flared, and where this occurs, remains limited. The purpose of this paper is to describe two methods for estimating venting and flaring volumes - self-reports required by state law and satellite imagery radiant heat measurements - and to compare these methods using the case of Texas Eagle Ford and Permian Basin venting and flaring practices from 2012 to 2015. First, we used data self-reported by companies to the Texas Railroad Commission (TxRRC), and National Oceanic and Atmospheric Administration (NOAA) data captured by satellite-based Visible Infrared Imaging Radiometer Suite sensors, to estimate the annual total volumes of gas vented and flared in the Eagle Ford and Permian Basin from 2012 to 2015. Next, we developed a method using a geographic information system to link and compare TxRRC and NOAA county-based and point-based volume estimates. Finally, we conducted case studies of two oil and gas fields to better understand how TxRRC and NOAA venting and flaring volumes differ. We find both TxRRC and NOAA estimated venting and/or flaring volumes steadily increased from 2012 to 2015. Additionally, TxRRC reports captured about half the volumes estimated by NOAA. This suggests that self-reported volumes significantly underestimate the volume of gas being vented or flared. However, this research is limited by the data currently available. As such, future research and policy should further develop methods to systemically capture the extent to which oil and gas extraction facilities vent and flare natural gas.