Dubois, PA Tri-County Sunday
21 February 2009
DuBOIS -Withdrawal and treatment are two of the largest issues related to water and Marcellus Shale drilling in Pennsylvania.
Disposal of the fluids used and generated during and after the drilling process is being regulated to protect water sources. Currently, all waste fluids produced during the drilling process is collected in a pit with a liner with at least two feet of freeboard to protect groundwater and nearby surface water.
Final use or disposal of the fluids produced by the drilling process depends on which layer of the process it is produced by. The freshwater which is encountered in the first several hundred feet of drilling can be reused in the drilling process, be land applied, or trucked to an on-site facility for treatment.
"Wastewater is a huge issue right now," said Penn State Extension water resources specialist Bryan Swistock Thursday at a persentation on natural gas exploration. "A lot of people consider it a bottleneck of gas drilling's future. It is difficult and expensive to take salt out of water. Up until now, we've relied on dilution to do that. We take it to a treatment (plant) and take out the metals and sediment and then we are left with a salt solution which goes into a stream where it is diluted. You can't keep doing that forever."
Bottom hole fluids, which are very old salt water deposits, are encountered very deep underground during drilling. These fluids are commonly referred to as "brines." Production fluids, which are produced with the natural gas after the well is in production, have a similar chemistry to bottom hole fluids.
"Another issue is the ability to treat the fluid with non-traditional chemicals in them," Swistock said. "Location of treatment is also an issue because it has all traditionally been in Western Pennsylvania. You don't have much treatment in north central or northeastern Pennsylvania, so there needs to be infrastructure which will take time and permitting to build."
Stimulation fluids are used to improve gas recovery in hydrofracturing. In hydrofracturing large amounts of water mixed with material such as sand, oils, gels, acids, alcohols and other manmade organic materials is pressurized and used to fracture the rock to increase gas production. Historically, the exact additives in the stimulation fluids have been difficult to regulate because the mixture was considered proprietary. In October 2008, changes to the state gas well drilling permit along with action by the River Basin Commissions require companies to disclose the additives used in hydrofracturing as part of the gas drilling permit application and approval. In Texas, Wyoming and Arizona where drilling has been done, the majority of wastewater from the process is put in evaporation ponds. Swistock said, because of the weather conditions in Pennsylvania this is not a viable option.
The brine may be trucked to municipal or industrial treatment plants or applied to rural and gravel roads for dust control, but ultimately the process Pennsylvania has its sights on is the recycling of the fracing fluids.
"Keep in mind when they frac a well only a certain amount of that fluid comes back to the surface, probably 30 to 40 percent on average. So if you put a million gallons of fracing fluid into the ground, you might get 300,000 to 400,000 gallons back," Swistock said. "Much of what comes back to the surface immediately is relatively clean and can be used again. What stays down longer picks up more minerals and metals and has to be treated. There is so much research going on right now."
Water withdrawal is another major concern. With newer and deeper gas well drilling technologies, withdrawals generally exceed 10,000 gallons of water per day.
Swistock said in Pennsylvania a person does not own water on or underneath their property, but can control access to it. This is one way landowners can control water use as withdrawal points may be from streams, ponds, lakes, or other water sources, which can have significant effects if not done carefully.
"So far we have seen easy withdrawals, meaning easy to permit. Easy to permit would be purchasing water from a municipal water supplier," Swistock said. "Another relatively easy one is small withdrawals from large rivers."
Concerns over water use during gas well drilling prompted changes to the state permit in October 2008. The permit now must include information on water sources and locations of water to be used in the drilling process, the impacts of the withdrawals on that water source and that the withdrawals have been approved by a river basin commission.
"How I'd like to see this play out is that water is impounded in reservoirs during times of high flow in March and April," Swistock said. "Then this stored water can be used throughout the year and during the summertime and fall when water is less available all around."
There is also opportunities for companies to pursue beneficial reuse of acid mine drainage and other impaired water resources.
A gas well permit which used to cost a few hundred dollars, has been raised to a few thousand so 40 additional DEP employees could be hired for inspection and enforcement related to Marcellus Shale drilling.
Reported by Katie Weidenboerner, Tri-County Sunday. Email: katiew@thecourierexpress.com* katiew@thecourierexpress.com