Flaming Taps: Methane Migration and the Fracking Debate

Susan Phillips / StateImpactPA

Methane migrated into Dimock res­i­dent Norma Fiorentino’s water sup­ply, caus­ing her water well to explode. DEP later blamed Cabot Oil and Gas.

One of the most iconic sym­bols of the frack­ing debate is the video of a man set­ting his tap water on fire in Colorado.

Frack­ing, which refers to hydraulic frac­tur­ing, is a tech­nique used to extract nat­ural gas, and has become syn­ony­mous with all things gas drilling. It involves shoot­ing water, sand and a mix of chem­i­cals at high pres­sure deep into a well­bore to help split the shale rock and release the gas.

Some worry frack­ing fluid will leak out of a well and con­t­a­m­i­nate aquifers. In fact, a recent draft EPA study about water pol­lu­tion in Pavil­ion, Wyo., does make that link. Frack­ing waste­water has also spilled and con­t­a­m­i­nated sur­face water.

But frack­ing does not put methane into tap water.   Tap water blow torches, as seen in the doc­u­men­tary film Gasland, result from methane migra­tion.  Such move­ments of gas may or may not be related to drilling. But they do not result from frack­ing. And that’s an impor­tant dis­tinc­tion to make.

Trac­ing the source of migrat­ing methane, or stray gas, can be com­pli­cated and mys­te­ri­ous. Inves­ti­ga­tors often use iso­tope iden­ti­fi­ca­tion to get a “fin­ger­print” of the gas. But just as in law enforce­ment, fin­ger­prints can be tricky.

In the case of Dimock, Pa., wells drilled by Cabot Oil and Gas were fracked. But the Penn­syl­va­nia Depart­ment of Envi­ron­men­tal Pro­tec­tion did not con­nect the flam­ing water taps to frack­ing; reg­u­la­tors blamed poor well con­struc­tion and over-pressurization.

When a well­bore is drilled, a steel cas­ing is sent down the hole. Then cement is poured down, and pushed upward to seal the open space between the steel cas­ing, and the rock. That cement seal is sup­posed to pre­vent any gas, or fluid, from migrat­ing into or out of the well­bore, and from using that space between the rock and the newly drilled well as a con­duit. But that cement job doesn’t always work. And in the case of Dimock, it failed miserably.

Fred Bal­das­sare worked as an inspec­tor for DEP, where he spent six years inves­ti­gat­ing methane migra­tion and helped out on the Dimock case. He was the guy who looked at the geo­chem­istry of those flam­ing taps. In other words, he looked at the gas fin­ger­print. Bal­das­sare says the evi­dence link­ing Dimock’s flam­ing tap water to gas drilling by Cabot is overwhelming.

But where that gas actu­ally came from, whether it was from deep in the Mar­cel­lus for­ma­tion, or whether it was from a more shal­low for­ma­tion, is unclear.

“The gas was nearly an exact match to the gas com­ing from the Mar­cel­lus wells,” said Bal­das­sare. “But we couldn’t say it came from there because there are gas deposits above the Mar­cel­lus that have the same fingerprint.”

And that’s where it gets tricky.   One big prob­lem in Penn­syl­va­nia is this: With­out a base­line water test before any drilling activ­ity begins, how does one prove high lev­els of methane didn’t already exist in the water well i.e. from nat­ural migra­tion? And few res­i­den­tial wells in the state have those pre-drilling readings.

Gas can get into well-water in var­i­ous ways.   Bal­das­sare says drilling, along with a bad cement job, can cause any gas pocket that has been sta­ble for thou­sands of years to start mov­ing. That’s because methane, under high pres­sure, wants to go to an area of lower pres­sure. And drilling, whether it’s a ver­ti­cal well, hor­i­zon­tal well, deep well, or shal­low well, can pro­vide that opportunity.

But other things can, too, such as coal min­ing. It can also hap­pen nat­u­rally. And that’s where the impor­tance of estab­lish­ing that gas fin­ger­print comes in. Bal­das­sare says he spent a lot of time track­ing methane migra­tion long before the first Mar­cel­lus Shale gas well was even drilled.

“There are exam­ples of [methane migra­tion] through­out the North­east that have noth­ing to do with gas activ­ity,” says Bal­das­sare. “And there are oth­ers that do hap­pen because of drilling or min­ing activity.”

Reports of methane migrat­ing into water wells date back to the 1800’s. It can orig­i­nate in a coal bed. A report put out by the Penn State Coop­er­a­tive Exten­sion Ser­vice in 2009 says deep water wells in the north­ern and west­ern parts of the state are the most sus­cep­ti­ble. Still, the study also says nat­ural methane migra­tion is a rare occurrence.

When methane migrates, it will dis­solve in water, but once the water reaches a lower pres­sure zone, the gas wants to get out. That’s why peo­ple expe­ri­enc­ing methane in their water sup­plies will first notice a spurt­ing at the tap, or bub­bles in a glass of water. If that hap­pens, the con­cen­tra­tion is high enough to be com­bustible and the pres­ence of the col­or­less, odor­less methane becomes a danger.

If it’s above 28 mil­ligrams per liter, it’s con­sid­ered dan­ger­ous, and can col­lect in a tight space. When trig­gered, it could explode. That’s what hap­pened when Dimock res­i­dent Norma Fiorentino’s water well blew up.

Nei­ther the fed­eral EPA nor the state DEP con­sider drink­ing water with methane to be harm­ful. But there are few stud­ies on the long-term health impacts of drink­ing water with high lev­els of methane.

Recent stud­ies on the con­nec­tion between methane migra­tion and gas drilling has pro­duced con­flict­ing con­clu­sions. Duke Uni­ver­sity researchers pub­lished a report in May, 2011 that found higher con­cen­tra­tions of methane in water wells near gas drilling sites in Penn­syl­va­nia. But another study, pub­lished by Penn State Uni­ver­sity in Octo­ber 2011, found no cor­re­la­tion between the pres­ence of nat­ural gas wells and the pres­ence of methane in drink­ing water.

The duel­ing stud­ies have fueled con­fu­sion over the link between flam­ing taps and nat­ural gas drilling. In Decem­ber 2011, the EPA pub­lished a draft report on water pol­lu­tion in Pavil­ion, Wyo. In that report, the EPA says methane migra­tion may be due to gas drilling.

“Although some nat­ural migra­tion of gas would be expected above a gas field such as Pavil­lion, data sug­gest that enhanced migra­tion of gas has occurred within ground water at depths used for domes­tic water sup­ply and to domes­tic wells. Fur­ther inves­ti­ga­tion would be needed to deter­mine the extent of gas migra­tion and the fate and trans­port processes influ­enc­ing migra­tion to domes­tic wells.”

So once methane migrates into a water sup­ply, what then? Bal­das­sare says proper vent­ing and aer­a­tion does work. But some home­own­ers suf­fer­ing from high lev­els of methane in their water wells have expressed doubts about the vent­ing sys­tems, as well as fil­tra­tion sys­tems. Bal­das­sare also says if the source of the stray gas is halted, even­tu­ally, the water will be free of the methane through nat­ural processes. But it’s unclear how long that could take.