Development of a Forced Advection Sampling Technique (FAST) for Quantification of Methane Emissions from Orphaned Wells

Abstract. Orphaned wells, meaning wells lacking responsible owners, pose a significant and poorly understood environmental challenge due to their vast number and unknown associated emissions. We propose, develop, and test a novel method for estimating emissions from orphaned wells using a Forced Advection Sampling Technique (FAST) that can overcome many of the limitations in current methods (cost, accuracy, safety). In contrast to existing ambient Gaussian plume methods, our approach uses a fan-generated flow to create a jet between the emission source and a point methane (CH₄) sensor. The fan flow field is characterized using a collocated sonic anemometer to measure the 3D wind profile generated by the fan. Using time-series measurements of CH₄ concentration and wind, a simple estimate of the CH₄ emission rate of the source can be inferred. The method was calibrated using outdoor controlled release experiments and then tested on four orphaned wells in Lufkin, TX, and Osage County, OK. Our results suggest that the FAST method can provide a low-cost, portable, fast and safe alternative to existing methods with reasonable estimates of orphaned well emissions over a range of leak rates.