Development of a Forced Advection Sampling Technique (FAST) for Quantification of Orphan Well Methane Emissions
Mohit Dubey, University of California, Berkeley
Orphaned wells, or wells lacking responsible owners, pose a significant and poorly understood environmental challenge. In the United States (U.S.) alone, there are approximately 120,000 documented orphan wells, with an estimated 310,000 to 800,000 more undocumented wells. Methane (CH4) emissions from these wells are vastly underestimated, by 150% in Canada and 20% in the U.S., making them the most uncertain CH4 source in both countries. In this work, 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. 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 sensor. Using a colocated anemometer to measure the 3D wind profile generated by the fan, the fan flow field is characterized. From this, a simple estimate of the CH4 emission rate of the source can be obtained. The method is calibrated using an outdoor controlled release experiment and blindly tested on five orphan wells in Lufkin, TX, and Osage County, OK. Preliminary results suggest that the FAST method can provide a low-cost, portable, fast and safe alternative to existing methods to provide reasonable estimates of orphan well emissions over a large range of leak rates.