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Cases of drilling sending gas into water supplies decline in Pennsylvania August 9, 2016 9:18 AM Pittsburgh Post-Gazette POWERSOURCE By Laura Legere / Harrisburg Bureau

Cases of drilling sending gas into water supplies decline in Pennsylvania

August 9, 2016 9:18 AM

Pittsburgh Post-Gazette


By Laura Legere / Harrisburg Bureau

In a new state annual report full of statistics about Pennsylvania oil and gas development in 2015, one of the more notable figures is zero.

It stands for the number of new confirmed cases when oil or gas wells channeled loose gas into aquifers and drinking water supplies, once one of the more bedeviling problems associated with shale gas development in the state, especially the northeastern quarter.

Following a grim peak of 28 stray gas cases affecting 57 water supplies in 2010, for the first time last year there were no new confirmed stray gas cases and, therefore, no new water supplies harmed by them.

The milestone is not likely to stand quite so starkly. The head of the Pennsylvania Department of Environmental Protection’s oil and gas office said that when conclusions are reached in some open stray gas investigations, the 2015 statistics will probably not remain zero. (The department attributes cases to the year they were opened even if they are confirmed in a subsequent year.)

Regardless, DEP deputy secretary Scott Perry said, the reduction in cases marks significant progress on an issue that strained public confidence in the industry with early shale-era contamination cases, some of which have still not been completely resolved.

“There truly is a positive trend here,” Mr. Perry said.

The progress is not simply a byproduct of the steep reduction in drilling in the state, he said, citing calculations by a DEP geologist who found the number of stray gas cases are down per well.

By DEP’s official tally, oil and gas operations have disrupted 281 drinking water supplies since December 2007, either through pollution or by diminishing the flow of water to taps. For years, stray gas from leaking wells was the dominant category of contamination.

DEP’s oil and gas annual report says 86 confirmed stray gas cases between 2009 and 2015 affected 154 water supplies. “It is not uncommon for a single confirmed gas migration case to affect multiple water sources,” the agency wrote.

Methane in water wells can create a risk of explosion or asphyxiation if the gas escapes from water and collects in confined spaces. It can also act as a catalyst for chemical and biological reactions in water that can give it a foul odor, taste or color.

When gas drilling is the cause of methane-tainted water, the source is usually gas trapped in the layers of rock between the surface and the drillers’ deep target, like the Marcellus Shale. If operators do not anticipate the gas pockets or use materials to block them, the pressurized gas is likely to create tiny channels in the cement barrier as it sets, creating a pathway up the well for the gas to reach groundwater.

Ongoing improvements

Regulators and industry experts credit a variety of improvements for the declining incidence of stray gas cases.

Companies are taking better care to survey the notoriously complex geology of the region before they drill, spending more time studying the nuisance layers of gas-bearing rock as they pierce them, and improving drilling processes and cement blends that keep gas from interfering with the protective barriers meant to seal off wells from their surroundings.

“It’s a holistic approach,” said Fred Baldassare, whose Murrysville consulting firm Echelon Applied Geosciences specializes in gas and groundwater investigations. He said companies have evolved quickly to avoid repeating past mistakes. “Nobody does things the way they did in 2009.”

Stronger well construction rules adopted by the state in 2011 have also contributed to the decline in stray gas cases, as has a no-tolerance enforcement approach when tests reveal signs of gas moving between layers of cemented steel casings inside wells, Mr. Perry said.

“I definitely credit the rules,” he said, “but I also credit the industry for actively seeking superior ways of drilling, casing and cementing their wells.”

In 2008 and 2009 when shale development took hold, companies’ inexperience with Pennsylvania’s unique and varied geology led to problems. Out-of-state operators brought with them assumptions about the “relatively uncomplicated, flat” shallow geology of Texas and Oklahoma “where there’s nothing to worry about in the first 2,000 feet,” Mr. Perry said. “Well, here there was.”

Even expectations borrowed from the South about how long it takes for cement to cure were upended by Appalachia’s cold, deep rocks, Mr. Perry said. Here, the cement tended to stay in its plastic state for longer, creating a wider window of vulnerability when gas can cut the cement.

Now companies have adopted sophisticated polymers in their cement mixes to create a better seal between bare rocks and well casing, Mr. Baldassare said. They scrutinize seismic data before drilling to learn more about the natural hazards embedded in the geology above their target rock layer. They will drill with water that is heavy enough to limit intermediate gas from entering the borehole.

Both companies and DEP are also much more knowledgeable now about methane that exists in groundwater as a natural condition, as well as how the concentration of gas can fluctuate because of things like weather and how often a water well is used.

Regulators are more likely to monitor conditions to look for natural variability before drawing conclusions, said Mr. Baldassare, who was DEP’s primary stray gas investigator before he started his consulting firm.

Disruptions still happen

The progress on stray gas cases does not mean that water supply disruptions related to oil and gas drilling in Pennsylvania have stopped.

DEP sent out 26 water impact determination letters to property owners in 2015, and an additional six letters so far this year, that tied private water supply disruptions to oil and gas wells. Some of the 2015 letters attribute methane and other gases in the water supply to drilling operations, but the investigations in those cases began in earlier years and would have been counted in the agency’s data in the year the investigation began.

In most cases, though, DEP inspectors reported different kinds of drilling-related influences on water supplies last year: increased metals like iron and manganese, cloudiness, higher concentrations of salts, and the presence of foaming agents.

Several letters were connected to a contamination case in Potter County in which an unauthorized surfactant containing isopropanol that Franklin Park-based JKLM Energy used to extract a broken drill bit escaped into the aquifer, affecting six water supplies.

Some impacts were temporary, the letters say, and others require a more intensive response to restore water supplies to their prior quality and quantity.

Many of the strategies and regulations that have minimized stray gas cases are expected to apply as companies drill more frequently into deeper rock formations, like the Utica Shale. Whether stray gas cases remain rare will depend on companies new to the basin adopting the same vigilance that current operators have developed over time.

“It only takes one or two operators who don’t have the same care as everyone else to create a bad situation,” Mr. Baldassare said.

Laura Legere:



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