Low-producing “marginal” wells contribute less than a tenth of the oil and gas produced in the U.S. So why are they responsible for half of the industry’s methane emissions? A new study from Environmental Defense Fund provides the first nationwide analysis of low-producing wells and their staggeringly disproportionate climate impact.
When it comes to the causes of climate change, no greenhouse gas is more impactful than methane — far more so than carbon dioxide, by many measures. In the U.S., the second-biggest source of methane pollution is the oil and gas industry.
“Based on previous research and a whole host of measurement-based research in peer-reviewed literature, we know that nationally the oil and gas production sector is the largest contributor to total methane emissions from oil and gas operations, accounting for about 60% of the total,” said Mark Omara, Senior Analyst at the Environmental Defense Fund (EDF) and lead author of a recent study focusing on low-producing wells. “We also know that these emissions are often significantly under-estimated in official inventories.”
Among oil and gas wells, however, the facilities responsible for the bulk of emissions bring relatively little natural gas to market. Omara’s research, published last spring in the journal Nature Communications, found around half of all methane emissions in the U.S. are coming from “marginal” oil and gas wells producing less than 15 barrels of oil equivalent per day. Collectively, such wells account for only about six percent of all oil and gas produced in the U.S.
If these emissions were captured it would represent enough natural gas to supply 3.6 million American homes for a year, or the residential natural gas demand for the entire state of Ohio.
Where’s all that methane coming from?
Much of the natural gas extracted by marginal wells — about 4 million metric tons a year — goes straight into the atmosphere, either discharged intentionally or simply leaking from ill-maintained and unmonitored infrastructure. That’s an enormous waste of fuel at a time when energy prices are at historic highs, and only going up.
“If these emissions were captured it would represent enough natural gas to supply 3.6 million American homes for a year, or the residential natural gas demand for the entire state of Ohio,” said Omara. “Simply put, our study suggests these emissions are significant and they cannot be ignored.”
The study also notes low-producing U.S. wells collectively emit the greenhouse-gas equivalent of 88 coal-fired power plants — but, unlike carbon released through coal combustion, fugitive emissions from gas wells produce no useable energy in return.
Any way you look at it, it’s a terrible trade-off.
Yet in gas-producing states like Pennsylvania, low-producing wells are often subject to lighter regulation than their more efficient counterparts. The EDF study makes the strongest case yet for flipping that disparity. Comparing total methane emissions from different natural gas fields around the country, researchers found the largest share of regional methane emissions come from low-producing well sites in the Appalachian region.
“There is a very large number — nearly 200,000 — [of] low-producing wells in the Appalachian region. This represents 30% of all the low-producing wells in the country,” said David Lyon, a Senior Scientist with EDF and co-author of the study. “There is also a very large number of really old, what we call ultra-low producing wells in this region. We have had at least three studies that have documented evidence of excessive and avoidable methane emissions from these wells in this region due to things like maintenance issues and lack of equipment inspection and repairs.”
So what can be done to reduce emissions from these wells?
“First, what’s needed is to plug a large number of these wells… practically, many of them are so low-producing that the most cost-effective solution will be to shut in the well,” said Lyon.
There are federal resources available for well plugging projects. Technology is also progressing to help reduce emissions at the source. Most commonly, infrared cameras are used to detect leaks, while newer innovations include screenings from airplanes to monitor a larger number of well sites and continuous emission monitors.
Above: Infrared imaging technology allows operators to cost-effectively detect methane emissions from gas wells. Video source: Environmental Defense Fund.
Lyon stressed that federal support will continue to be an essential piece of the solution.
“It’s really important that EPA has strong rules that address all wells that include these marginal wells and is flexible in their use of technology,” said Lyon.
There is still plenty of research to be done when it comes to understanding methane emissions from oil and gas wells.
“Even though we have done a terrific job at consolidating the measurement-based data that’s been provided in the past few years, there is still a need for comprehensive data collection, particularly for these low-producing well sites. We need to understand better how emissions are attributed by region… we need to understand better the technologies that can best be applied to reduce these emissions,” said Omara. “Those studies are critical in helping us reduce methane emissions from these sites.”
“There is also the issue of how this pollution affects marginalized communities… I see this as an important study that will be critical in helping us evaluate the impacts of oil and gas, not only low producing wells but also oil and gas operations in general,” he added.
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