Tuesday, September 17, 2013

UT Study Measures Methane Leakage at 489 Gas Wells--Finds Low Rate

Here is the story in today's NYT about the University of Texas methane leakage study:

Here is the link to the study published by the Proceedings of the National Academy of Science:

The study was done in collaboration with the Environmental Defense Fund and 9 drilling companies. It's method was actual measurement of emissions at 150 drilling sites, containing 489 wells that were all hydraulically fractured, located in a variety of regions across the United States.

The study extrapolates from its measurements to conclude that methane leakage amounts to 0.42% of gas produced, considerably lower than the most recent Environmental Protection Agency estimate.

This study is an important contribution to defining the methane leakage problem and further reducing methane leakage.  And further reducing methane leakage, as well as flaring and other air pollutants from gas production, should be a goal that most would support.

Is the study definitive or the last word? Absolutely not and more research will be done.

It took measurements at about 2% of the gas wells drilled in a year. It involved the voluntary cooperation of 9 drilling companies and has a possible self-selection bias. The methane leakage performance at these wells is good, though it could be better, and may be representative of good performing companies and wells.

As such, the study may be the best case scenario that identifies an achievable standard of excellence that should become a requirement for all gas drilling companies to meet.  Simply put, if these shale gas wells can perform at this low level of leakage, then all shale gas wells that are hydraulically fractured should be able to do so.

What the study does show definitively is that "green completions" work very well, reducing methane leakage by 99%.  And the EPA rule on green completions takes affect in January 2015. That is good news, indeed.


  1. Not definitive study should be in the title! Were any results offered from scheduled blow offs at compressor sites? If they volunteered I suspect they were already ahead of the curve. I would like to see constant monitoring and data collected. I would really like to see 24/7 air quality monitoring done in the shalefields...yesterday.

  2. Victoria,

    I believe that this is just the first results of a multi-faceted study that is investigating the different stages of gas production separately, some of which you mention above. More results are yet to come.

    Also, I do believe that the PA DEP does have some 24/7 air monitoring stations set up in the shale fields.

    In regards to the concerns over "cherry picking" the sites, Steven Hamburg, the chief scientist at E.D.F., said this:

    Some have claimed that the companies picked the timing and locations of sampling. That assertion is false and based on nothing more than conjecture. The paper clearly lays out the basis for how the sites were selected and the companies were given no input or control over that process. The scientific team gave its criteria to the companies and all sites meeting those criteria were made available. There was no cherry picking and no sanitizing. Natural gas wells are not restaurant kitchens that can be ‘cleaned up’ before the inspectors come — emissions levels from activities like well completions are determined by geology and the equipment on the site, the companies couldn’t have influenced them to any significant degree if they tried. And we saw zero evidence that they tried.

    There is much more interesting discussion on the paper from its authors and its critics on Andy Revkin's Dot Earth Blog:


    Hope all is well with you!