Pennsylvania Oil and Gas Methane Emissions: Uncovering the Whole Picture


In mid-February, the Environmental Defense Fund (EDF) released a study estimating that methane emissions from active Pennsylvania oil and gas wells were five times higher than previously estimated. This estimate came from analyzing the results of 16 peer-reviewed studies. About half of the estimated methane emissions came from conventional gas wells, which leak about 23% of their volume. While unconventional (fracked) gas wells leak a smaller percentage of their gas (about 3%), their higher overall gas volume makes the amount of gas released by each type of well roughly equal. EDF’s data included integral infrastructure such as compressors, produced water tanks, and flares. While the Pennsylvania DEP has released emissions regulations for new unconventional wells and related infrastructure, promised regulations for existing oil and gas infrastructure have not been released.

A well pad under construction in northeast Pennsylvania. Photo by Coryn Wolk

EDF and other organizations advocate for tighter emissions regulations that would force adoption of better leak-prevention methods and technologies. EDF’s analysis shows that leak prevention technology would greatly reduce emissions from natural gas wells and their associated infrastructure. However, existing maintenance and regulatory problems in Pennsylvania prompt some questions about this solution.

As EDF’s data shows, conventional gas wells are a massive contributor to methane emissions in Pennsylvania. This is in part because many have been abandoned and left uncapped. With little documentation of responsibility, limited regulatory capacity, and abysmal record-keeping, this problem has been slow to improve. As unconventional gas wells date from a much more recent time span (2009 at the oldest), current records and ownership are more accessible. However, beyond the roughly 5% of unconventional gas well casings that fail immediately, the majority are predicted to fail over a 100-year timespan. For reasons including the volatility of natural gas prices and failed small-scale speculator companies, many unconventional wells have already undergone changes of ownership that led to issues with responsibility and liability. Will the technological fixes that EDF advocates endure over decades and potential future site abandonment?

Given the years-long struggle to codify even government-sanctioned state and federal methane regulations, these questions may seem premature. However, the Pennsylvania government’s refusal to consider or plan for the long-term issues likely to arise from fossil fuel infrastructure has led to our current collection of crumbling and/or polluting infrastructure largely left in the lap of state and local governments and residents.

PSR Philadelphia also attended a presentation by Peter DeCarlo, PhD, an associate professor who studies atmospheric chemistry in Drexel’s College of Arts and Sciences and College of Engineering, about his 2012 and