Author Description

Hydraulic fracturing is a technique developed initially to stimulate oil production from wells in declining oil reservoirs. More recently, it has been used to initiate oil and gas production in unconventional (i.e., low-permeability) reservoirs where these resources were previously inaccessible. This process now is used in more than 90% of new oil and gas production wells. Hydraulic fracturing is done after a well is drilled and involves injecting large volumes of water, sand (or other propping agent), and specialized chemicals under enough pressure to fracture the formations holding the oil or gas. The sand or other proppant holds the fractures open to allow the oil or gas to flow freely out of the formation and into a production well. Its application, along with horizontal drilling, for production of natural gas (methane) from coal beds, tight gas sands, and, more recently, from unconventional shale formations, has resulted in the marked expansion of estimated U.S. natural gas reserves in recent years. Similarly, hydraulic fracturing is enabling the development of unconventional domestic oil resources, such as the Bakken Formation in North Dakota and Montana. However, the rapidly increasing and geographically expanding use of fracturing, along with a growing number of citizen complaints and state investigations of well water contamination attributed to this practice, has led to calls for greater state and/or federal environmental regulation and oversight of this activity. Historically, the Environmental Protection Agency (EPA) had not regulated the underground injection of fluids for hydraulic fracturing of oil or gas production wells. In 1997, the U.S. Court of Appeals for the 11th Circuit ruled that fracturing for coalbed methane (CBM) production in Alabama constituted underground injection and must be regulated under the Safe Drinking Water Act (SDWA). This ruling led EPA to study the risk that hydraulic fracturing for CBM production might pose to drinking wate