By Aimee Delach, FOR VolunteerDepending on who you talk to, hydraulic fracturing (aka “fracking”) may be presented as an economic boom, the path to energy independence, or a fast track to a polluted watershed. As interest mounts in Virginia’s own natural gas reserves, it is important that all residents have a clear understanding of the issue.
Put simply, hydraulic fracturing is the process of injecting water into the ground to extract natural gas that is trapped within small pores of deeply buried rock. The water pressure (“hydraulic”) cracks open the rock (“fracturing”), and small bits of sand injected along with the water hold the pores open, allowing natural gas to rise back out of the well. Areas where fracking can yield natural gas are not distributed evenly across the landscape.
Like oil and coal, natural gas is a “fossil fuel,” a term that highlights the great age of these energy sources. They are the remains of ancient plant material that sank into swamps or shallow seas, wereburied in sediments, and instead of decomposing normally, were transformed by time, pressure, and lack of oxygen into their current forms. In some places, gas and oil collect into fields that can be drilled conventionally. A large quantity, however, is bound tightly into the rocks where it was originally trapped, generally a coal seam or a sedimentary rock, called shale.
Photo by Sky Truth
The main area of interest for gas production in central Virginia is the Taylorsville shale formation. The Taylorsville Basin, which starts east of Richmond and stretches almost to Baltimore, underlays a swath of Stafford, Caroline, King George, and King William counties. It is one of a string of basins along the East Coast that formed 227 million years ago as the Atlantic Ocean opened and Americas split off from the rest of the world’s land mass.
Each basin became a productive lake before eventually filling with sediments that trapped organic matter and were slowly pressed into shale rock. Now buried almost 10,000 feet below the surface, the basin is estimated to have a 95% chance of harboring at least 516 billion cubic feet of gas (bcfg), a 50% chance of 985 bcfg, and 5% chance of as much as 1880 bcfg (or 1.8 trillion).
By contrast, the Marcellus shale formation, which has launched a gas boom in nearby states, is 400 million years old and extends through West Virginia, Pennsylvania, and New York, and has been estimated at 140 trillion cubic feet of gas. The southeast boundary of that formation underlays the far western part of Virginia, but to date has been subject to only a single exploratory well.
One of the most important questions about potential fracking in the Taylorsville region is whether it can be done safely, and without contaminating water sources. Fracking proponents point to the fact that the fracturing takes place thousands of feet below the water table, minimizing the chance that injected water and associated chemicals (which can include acids, disinfectants, thickeners, and anti-corrosive agents) will percolate back into groundwater.
Nonetheless, there have been multiple reports in active gas regions about problems with wells and surface waters. The Natural Resources Defense Council, for instance, has compiled anecdotes from a dozen states, including Virginia.
Hydraulic fracturing is currently in use here, at roughly 1,800 of the 5,600 gas wells in the far southwestern part of the state. The fracking process in use there is slightly different, as it is drawing on gas associated with coal seams rather than shale beds. This process drills to much shallower depths (about 1,000 feet) and produces more wastewater at the surface than shale fracking. Thus, the effects are not entirely comparable.
The reports of water issues associated with shale gas, like those in the Marcellus wells in Pennsylvania, are more relevant to people attempting to predict whether development of the Taylorsville Basin will be problematic to local water resources, including the Rappahannock. While the fracturing itself would take place at great depth, reaching these areas would entail drilling through areas important for surface and groundwaters.
As with any industrial process, extreme caution must be taken to ensure that there is no leakage along the well bore, or improper handling of fluids, chemical additives, wastewater, extracted gas and other materials at the surface.
Sources:
Enomoto, C. B. 2013. Energy Resource Potential of the Mesozoic Basins in Virginia. http://www.dmme.virginia.gov/commercedocs/OFR_13_01.pdf
FracFocus Chemical Disclosure Registry. http://fracfocus.org/hydraulic-fracturing-how-it-works/hydraulic-fracturing-process
Milici, R.C. et al. 2012. Assessment of Undiscovered Oil and Gas Resources of the East Coast
Mesozoic Basins. USGS. http://pubs.usgs.gov/fs/2012/3075/fs2012-3075.pdf
Natural Resources Defense Council. Incidents where hydraulic fracturing is a suspected cause of drinking water contamination. http://switchboard.nrdc.org/blogs/amall/incidents_where_hydraulic_frac.html
U.S. Department of Energy. 2012 Annual Energy Outlook. http://www.eia.gov/forecasts/aeo/pdf/0383(2012).pdf
Virginia Department of Mines, Minerals, and Energy. Gas Well Viewer. https://maps.dmme.virginia.gov/flexviewer/DGO/
Virginia Department of Mines, Minerals, and Energy. Hydraulic Fracturing In Virginia. http://www.dmme.virginia.gov/DGO/HydraulicFracturing.shtml#FracingVA
