Environment: Study says abandoned oil and gas wells are a pathway for methane leaks from new fracking sites

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How much methane is leaking through damaged and abandoned wells? Photo via USGS.

Damaged well casings and fractured ground eyed in New York study

Staff Report

Spiderweb networks of abandoned oil and gas wells and cracked rocks may be significant pathways for methane leaks that aren’t being accurate measured, according to University of Vermont researchers who studied well patterns in New York.

The scientists said that not all abandoned wells are leaking — only those that are damaged, but given the large number of abandoned wells, those damaged casings can pose an evironmental risk, they concluded.“The debate over the new EPA rules needs to take into account the system that fracking operations are frequently part of, which includes a network of abandoned wells that can effectively pipeline methane to the surface,” said James Montague, an environmental engineering doctoral student at the University of Vermont.

The study focused on an area in New York State underlain by the Marcellus Shale formation, which had been fracked until a ban went into effect in the state in the summer of 2015. Oil and gas drilling since the 1880s left the area pockmarked by as many as 70,000 wells.

Because the location of so many wells is not known, the study used a mathematical model to predict the likelihood that the hydraulically induced fractures of a randomly placed new well would connect to an existing wellbore, finding a probability of between .03 percent and 3 percent of new fracking-induced fractures in the Marcellus formation would connect to an existing well bore.

While all fracking sites are different, most have a similar enough hydrocarbon profile that they attracted conventional oil and gas drilling in the past and most, like the Marcellus, have a large number of abandoned wells, many with unknown locations.

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