Marcellus shale wells ... DEP taking steps to assure drilling safety
Monday, June 21, 2010
By Jeff Corcino Staff Writer
In the wake of the gas well blowout in Clearfield County, the state Department of Environmental Protection continues to investigate what more can be done to improve the safety Marcellus shale natural gas wells.
"Although they are rare, we would like to see that it never recurs again," DEP spokesman Dan Spadoni said of gas well blowouts in a phone interview recently with The Progress.
As of June 3, 12 Marcellus gas wells were drilled in Clearfield County this year, 21 in Centre County and one in Jefferson County, according to the DEP Web site.
Spadoni said the cause of the Clearfield blowout is still under investigation so he can't comment on it specifically. But he said in general blowouts usually occur when there is a loss of control of the gas pressure, often due to a mechanical failure or human error.
Because the Marcellus shale is often more than one mile underground, gas extracted from the layer is under tremendous pressure and if there is a loss of control of the pressure, blowouts can occur, Spadoni said.
On June 3, at approximately 8 p.m. EOG Resources lost control of a well in Lawrence Township when it was preparing to extract natural gas from the well after hydraulically fracturing it.
The blowout spewed natural gas and frac flowback water 75 feet into the air causing a fire hazard, and the frac water threatened to flow into tributaries of Little Laurel Run, according to DEP.
Approximately 35,000 gallons of frac water were released from the well. Fortunately, it appears the water was contained prior to reaching any streams, but DEP continues to monitor the situation, according to DEP press releases.
Handling such emergencies has become an industry of its own and Wild Well Control of Houston, Texas, one of the companies that was called in to bring the EOG well under control, is considering locating one of its emergency response teams in Clearfield, according to previous articles in The Progress.
Wild Well Control provides firefighting, well control, engineering services and training services to oil and gas companies worldwide.
Two years ago the Clearfield Municipal Authority sold a five-year lease on its Marcellus shale gas rights on land surrounding its reservoirs to Carrizo Oil and Gas of Houston. No wells have yet been drilled on the land and, despite the recent blowout, CMA manager Jeff Williams said he has little concerns over the safety of Clearfield's water supply. Williams said the CMA required the company to sign an ironclad agreement to protect the quality of water in its reservoirs.
He said he is more concerned that a neighboring landowner would sell their gas rights with fewer protections than CMA's agreement than he is with any potential wells drilled on CMA land.
To extract the natural gas from the formation, modern drilling techniques such as horizontal drilling and hydraulic fracturing were developed in the oil industry due to the depth of the Marcellus shale.
To extract the gas, a well is drilled down 5,000-8,000 feet to the Marcellus shale layer. Once reaching the Marcellus shale layer the drill is turned and drills horizontally through the Marcellus shale layer to increase the yield of the well. The operators will drill in multiple directions from the original well shaft giving the well the appearance of spokes on a wheel, if viewed underground.
To further increase yields, large amounts of water, often mixed with some sand, other materials and chemicals, are pumped down into the well to fracture the rock around the well channel and free up even more of the natural gas that is trapped in fissures in the shale rock.
Drilling companies are required to release the contents of what it puts in its frac water.
A list of the chemicals can be found on the DEP Web site at: www.dep.state.pa.us/dep/deputate/minres/oilgas/FractListing.pdf.
Some of the water pumped into the well remains deep underground, but a portion of it will flow back to the surface. This is called frac flowback water.
The amount of water that returns to the surface can vary considerably anywhere from 10 percent to 30-40 percent of what was pumped in, Spadoni said.
Once it returns to the surface, frac flowback water contains high amounts of salts and can contain other chemicals and heavy metals so it is captured in lined lagoons or tanks for removal and treatment.
Because Marcellus wells are so deep, the water that remains underground in the well poses little risk to the environment. Spadoni said he has heard of no instance of contamination caused by frac water that remained deep underground in the well.
However, new regulations have been proposed to further strengthen the requirements for concreting and sealing the well channel to further reduce the chance of leakage of frac flowback water as it comes back to the surface, Spadoni said.
Most frac water spills occur due to mechanical failures such as leaking pipes or liners, etc., Spadoni said. Damage caused by these spills depends on the size of the spill and how much of the water finds its way into waterways.
When asked by The Progress about the risk of leakage, Spadoni said there should be no leakage of frac water if DEP regulations are followed correctly and equipment is properly maintained.
As for the captured frac flowback water, DEP is proposing strict new regulations regarding its treatment requiring total dissolved solids to be no greater than 500 mg/l, if it is to be discharged into commonwealth waterways. The 500 mg/l of TDS standard is the same standard for drinking water.
Last week the proposed regulations crossed its latest hurdle and was approved by the DEP's Independent Review Commission.
The new regulations are scheduled to take into effect the start of next year.
Due to the expense of treatment, many drilling companies recycle frac water, which requires less treatment than water being discharged to waterways.
One such treatment facility is being proposed by Hydro Recovery LP to be placed in Lawrence Township along Airport Road near Clearfield Lawrence Township Airport. The facility will remove much of contaminants from the frac water and send it back out to be used for hydro-fracturing again, according to a previous article in The Progress.
Some frac water is disposed of by deep well injection where the water is injected into deep underground wells. But there are few of such wells in the state because of its geology, Spadoni said. But Ohio does have some deep well injection sites.
In addition to recycling water, drilling companies obtain water for hydro fracturing by drawing from area streams and waterways, wells or purchasing water from municipal water companies, Spadoni said.
But to draw water from area waterways, the drilling company must first seek approval from the Susquehanna River Basin Commission to ensure the waterway isn't adversely affected by the draw down, according to Spadoni.
The Clearfield Municipal Authority has been approached by a drilling company to purchase excess water from the Moose Creek Reservoir but no agreement has yet been made, Williams said at the CMA meeting earlier this month.