Frequently Asked Questions

Energy

The USGS conducts basic research on geologic energy resources including oil, gas, gas hydrates, geothermal, and coal.

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Location of Marcellus Shale
RESERVES are quantities of oil and gas that are already discovered, recoverable, and commercial. The USGS assesses UNDISCOVERED RESOURCES, which are those that are estimated to exist based on geologic knowledge and theory. The USGS does not assess reserves because some of the data needed to make those calculations is not available to us. Much of...
Drilling Rig
The USGS uses a statistically-based process to calculate the likely range of its estimate. The range of values extends from a 5% or greater likelihood of occurrence (the F5 value, or largest estimated value) to less than 95% likelihood of occurrence (the F95 value, or smallest estimated value).  The F50 column is the value that occurs when 50% of...
Marcellus assessment units
According to the USGS assessment, the Marcellus Shale contains about 84 trillion cubic feet of undiscovered, technically recoverable natural gas and 3.4 billion barrels of undiscovered, technically recoverable natural gas liquids. Undiscovered resources are those that are estimated to exist based on geologic knowledge and theory, while technically...
A map showing the Barnett Shale assessment area in east Texas
Petroleum geologists have long known that oil and gas resources were present in “tight” or impermeable formations such as shale. But there was no feasible way to extract that oil and gas, so they were not “technically recoverable” and were not included in USGS assessment results. Thanks to new technologies, oil and gas can now be extracted from “...
Image shows a drill rig against blue mountains
Individual states regulate many aspects of oil and gas exploration and production. Federal land managers, such as the Bureau of Land Management (BLM), the U.S. Forest Service (USFS), and the U.S. Fish and Wildlife Service (USFWS) have some oversight of oil and gas activities on the lands they manage. This includes conducting environmental impact...
Map showing percentage of hydraulically fractured wells
Hydraulic fracturing is used in many established oil and gas producing regions of the country as well as some areas new to the petroleum industry. Maps of major shale gas, tight gas, and tight oil basins are available from the U.S. Energy Information Administration, although not all of the shale basins shown currently have production.
Image: Hydraulic Fracturing Well Heads
Hydraulic fracturing in vertical wells has been used for over fifty years to improve the flow of oil and gas from conventional reservoirs. However, the current practice of horizontal drilling coupled with multiple applications of hydraulic fracturing in a single well was pioneered in the late 1980s and has continued to evolve. Since the final...
Image shows USGS scientists standing beside a drill rig in protective gear.
The USGS is a science research agency with no regulatory, land management, or enforcement powers. This includes: research and assessments on the location, quantity, and quality of unconventional oil and gas resources whose production could involve hydraulic fracturing. Resource assessments estimate the quantity of oil and gas that is yet to be...
Image: Hydraulic Fracturing Sand
In general, hydraulic fracturing fluid is composed of water, proppant (typically sand), and chemicals.  A public website known as FracFocus has been established by industry that lists specific materials used in many, but not all, hydraulically fractured wells. Individual companies select a few chemicals to be used from hundreds that are available...
Generalized image showing the key points in hydraulic fracturing
Hydraulic fracturing, informally referred to as “fracking,” is an oil and gas well development process that typically involves injecting water, sand, and chemicals under high pressure into a bedrock formation via the well. This process is intended to create new fractures in the rock as well as increase the size, extent, and connectivity of...
Image: Hydraulic Fracturing Operation Underway
The actual practice of hydraulic fracturing (or “fracking”) is only a small part of the overall process of drilling, completing, and producing an oil and gas well. Environmental issues that are specifically related to hydraulic fracturing include: water availability spills of chemicals at the surface impacts of sand mining for use in the hydraulic...
Image: Withdrawing Water for Hydraulic Fracturing
There isn’t really a “typical” fractured well because the amount of water used depends on the rock formation, the operator, whether the well is vertical or horizontal, and the number of portions (or stages) of the well that are fractured. In addition, some water is recycled from fluids produced by the well, so the net consumption might be smaller...