QUANTIFYING METHANE EMISSIONS FROM ABANDONED LEGACY GAS WELLS IN INDIANA COUNTY, PENNSYLVANIA

For almost 150 years, Pennsylvania has played a major role in the production of natural gas. Its early history was poorly documented and regulated, leaving a great deal of uncertainty to the location and closure status of a large number of legacy wells. Early work to quantify methane emissions from these wells (Kang et al., 2014, Townsend-Small et al., 2016) show that abandoned gas wells make a small, but regionally significant contribution to regional methane emissions. This study examines variability of natural gas methane emissions using direct field measurement methods of flow rates and composition of venting emissions from abandoned natural gas wells in Indiana County, Pennsylvania. High-resolution time-series data show little variability in flow rates during an hourly period, however significant variability has been recorded over larger timescales (1,166 cm³/min to >3,840 cm³/min). This study demonstrates the need for further field measurements in order to understand variability of methane leakage from abandoned gas wells and to accurately estimate methane emissions.