An Overview of Unconventional Oil and Natural Gas: Resources and Federal Actions

The United States has seen a resurgence in petroleum production, mainly driven by technology improvements-hydraulic fracturing and directional drilling-developed for natural gas production from shale formations.Application of both of these technologies enabled natural gas to be economically produced from shale and other unconventional formations, and contributed to the United States becoming the world's largest natural gas producer in 2009.Use of these technologies has also contributed to the rise in U.S. oil production over the last few years.In 2009, annual oil production increased over 2008, the first annual rise since 1991, and has continued to increase each year since then.Between 2008 and 2012, U.S. annual crude oil production rose by 1.5 million barrels per day, with about 92% of the increase coming from shale and related tight oil formations in Texas and North Dakota.Overall petroleum liquids grew by 2.1 million barrels per day, with much of the increase in natural gas liquids coming from shale gas plays.Other tight oil plays are also being developed, and helped raise the prospect of energy independence, particularly for North America.The rapid expansion of oil and gas extraction using hydraulic fracturing-both in rural and more densely populated areas-has raised concerns about its potential environmental and health impacts.These concerns have focused primarily on potential impacts to groundwater and surface water quality, public and private water supplies, and air quality.States broadly regulate oil and gas exploration and production on non-federal lands.State laws and regulations governing unconventional oil and natural gas development have been evolving across the states in response to changes in production practices, largely in response to the use of high-volume hydraulic fracturing in combination with directional drilling.However, state regulations vary considerably, leading to calls for more federal regulation of unconventional oil and natural gas extraction activities.