In this Q&A, Vice President Robert Earle explores the benefits, risks, and litigation questions surrounding hydraulic fracturing, or "fracking," a process for extracting natural gas from shale deposits. As he explains, the process has raised public concerns about seismic disturbances and possible contamination of water.
Q: What is fracking? And why is it such a hot topic now?
Dr. Earle: "Fracking," or hydraulic fracturing, is a drilling technique used to extract natural gas. It has become more prominent because it has made a large amount of natural gas resources in shale deposits accessible over the past few years. According to the U.S. Energy Information Agency, this source of natural gas comprises perhaps as much as a 36-year supply of natural gas at current consumption rates, making it a game-changer for energy in the United States.
Until recently, most natural gas was extracted from deposits where the rock was fairly permeable, such as sandstone, so a natural gas well would simply bore into the rock, and the gas would come out because of the natural pressure. The industry has known for a long time that natural gas exists in less permeable rock, and particularly in shale deposits, but it has only recently begun to access it, because of advances in drilling technologies.
Here's how the process works: As with a more conventional natural gas well, a vertical well is drilled down to where the natural gas deposit lies. But then, in contrast to conventional techniques, horizontal bores are drilled into the deposit. Once this is done, a mixture of water, sand, and chemicals is forced into the deposit to crack the rock. The gas trapped in the less permeable rock can then flow out of the cracked rock.
Q: What regions of the country are particularly affected by this practice?
Dr. Earle: Significant shale deposits exist in 22 states. These include Utah and Wyoming in the West; the typical gas-producing states like Texas, Arkansas, and Louisiana; and Northeast states like Ohio, Pennsylvania, and New York. So the impetus to use fracking extends across the country.
Q: What are some potential regulatory and legal issues surrounding fracking?
Dr. Earle: There are many issues surrounding oil and gas development, in general, but a number of environmental issues are getting particular attention with respect to hydraulic fracturing. These range from concerns about seismic disturbances on the surface because of the deep underground explosions used to initiate fracking, to concerns about the amount of water used in the process, to the disposal of the water that flows back from the wells and the possible contamination of ground and surface waters.
Hydraulic fracturing, or "fracking," is a well-stimulation process used to maximize the extraction of underground resources including oil, natural gas, and geothermal energy. Take a closer look at how it works.
Q: What is the major source of concern about water pollution?
Dr. Earle: Some are concerned that the chemicals from fracking fluid could get into ground or surface waters. This could occur in a couple of ways. First, drillers are required to install casings around the drilling well to protect groundwater, but if those casings are not installed properly, fracking fluids can seep into the groundwater. Second, there is usually some flowback of fracking fluids, along with naturally occurring water from the reservoir, from the well to the surface. These fluids must be disposed of properly – that is, injected underground into an appropriate well, or treated and then discharged, or recycled for reuse as fracking fluid.
Q: Are fracking fluids left in wells an environmental concern?
Dr. Earle: This issue is still being studied. The current consensus, however, is that they pose no dangers if the well is drilled properly. That is because the gas reservoirs typically are thousands of feet below groundwater aquifers. Experts say that a fundamental principal of natural gas geology is that without an effective seal from rock formations above the reservoir, the natural gas would not have built up in the reservoir to begin with. So the same rock that sealed the natural gas in the reservoir also prevents the fracking fluids from seeping upward into groundwater aquifers.
Q: Are there critical fracking-related cases being heard now? What are they?
Dr. Earle: Several significant investigations, proceedings, and cases are going on right now, involving state and federal regulatory agencies and courts. Lawsuits have been filed in a number of states, including Texas and Pennsylvania, alleging contamination of groundwater. The accusations link illness and disease in humans and livestock with purported contamination. At the federal level, the U.S. Environmental Protection Agency is investigating allegations of illegal disposal of fracking fluids and has initiated a broad study of the effects of hydraulic fracturing. Regional water authorities are also examining fracking. The Delaware River Basin Commission has issued draft regulations on natural gas drilling in its jurisdiction.
Q: What is the likely future of fracking?
Dr. Earle: Hydraulic fracturing and horizontal drilling hold a lot of promise: America could tap a vast new supply of natural gas that could be profoundly beneficial to the economy and to energy security. The danger, however, if things are not done properly, is higher incidence of water pollution. With these kinds of concerns in mind, New York, for instance, has imposed a moratorium on hydraulic fracturing in some areas pending the completion of a study this summer. Given the amount of natural gas available from shale, it is important for us to develop this resource in an environmentally prudent manner. ■
Robert Earle is a Vice President in Analysis Group's San Francisco office.
(From Analysis Group Energy Bulletin, Spring 2011)