USGS Boosts Marcellus Estimates

- USGS Boosts Marcellus Estimates

Tuesday, August 23, 2011
U.S. Geological Survey

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 according to a new assessment by the U. S. Geological Survey (USGS).

These gas estimates are significantly more than the last USGS assessment of the Marcellus Shale in the Appalachian Basin in 2002, which estimated a mean of about 2 trillion cubic feet of gas (TCF) and 0.01 billion barrels of natural gas liquids.

The increase in undiscovered, technically recoverable resource is due to new geologic information and engineering data, as technological developments in producing unconventional resources have been significant in the last decade. This Marcellus Shale estimate is of unconventional (or continuous-type) gas resources.

Since the 1930's, almost every well drilled through the Marcellus found noticeable quantities of natural gas. However, in late 2004, the Marcellus was recognized as a potential reservoir rock, instead of just a regional source rock, meaning that the gas could be produced from it instead of just being a source for the gas. Technological improvements resulted in commercially viable gas production and the rapid development of a major, new continuous natural gas and natural gas liquids play in the Appalachian Basin, the oldest producing petroleum province in the United States.

This USGS assessment is an estimate of continuous gas and natural gas liquid accumulations in the Middle Devonian Marcellus Shale of the Appalachian Basin. The estimate of undiscovered natural gas ranges from 43.0 to 144.1 TCF (95 percent to 5 percent probability, respectively), and the estimate of natural gas liquids ranges from 1.6 to 6.2 billion barrels (95 percent to 5 percent probability, respectively). There are no conventional petroleum resources assessed in the Marcellus Shale of the Appalachian Basin.

These new estimates are for technically recoverable oil and gas resources, which are those quantities of oil and gas producible using currently available technology and industry practices, regardless of economic or accessibility considerations. As such, these estimates include resources beneath both onshore and offshore areas (such as Lake Erie) and beneath areas where accessibility may be limited by policy and regulations imposed by land managers and regulatory agencies.

The Marcellus Shale assessment covered areas in Kentucky, Maryland, New York, Ohio, Pennsylvania, Tennessee, Virginia, and West Virginia.

USGS is the only provider of publicly available estimates of undiscovered technically recoverable oil and gas resources of onshore lands and offshore state waters. The USGS worked with the Pennsylvania Geological Survey, the West Virginia Geological and Economic Survey, the Ohio Geological Survey, and representatives from the oil and gas industry and academia to develop an improved geologic understanding of the Marcellus Shale. The USGS Marcellus Shale assessment was undertaken as part of a nationwide project assessing domestic petroleum basins using standardized methodology and protocol.

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USGS Cuts Recoverability Assessment of NPRA Oil

USGS Cuts Recoverability Assessment of NPRA Oil

Thursday, May 05, 2011
U.S. Geological Survey

The U.S. Geological Survey assessment on the economic recoverability of undiscovered, conventional oil and gas resources within the National Petroleum Reserve in Alaska (NPRA) and adjacent state waters is now available online.

This economic analysis is based on a 2010 USGS resource assessment that determined how much undiscovered, conventional oil and gas in the NPRA is technically recoverable. These reports provide updates from the USGS 2003 economic analysis and 2002 resource assessment of the NPRA.

"The USGS conducts assessment updates to re-evaluate petroleum potential as new data and information become available," said USGS Energy Resources Program Coordinator Brenda Pierce. "Understanding how much undiscovered, technically recoverable resource might be present serves as a basis for calculating how much might be economically developed."

Technically recoverable resources are those that could be potentially produced using current technology and industry practices. Economically recoverable resources are those that can be sold at a price that covers the costs of discovery, development, production and transportation to the market.

The new economic analysis estimates that approximately 273 million barrels of undiscovered oil are economically recoverable at an oil price of $72 per barrel (comparable to $8 per thousand cubic feet of gas). About 500 million barrels of undiscovered oil are economically recoverable at $90 per barrel (comparable to $10 per thousand cubic feet of gas). These estimates do not include the discovered oil accumulations in northeastern NPRA that have not yet been developed.

The economically recoverable oil estimates above are dependent upon gas exploration in the NPRA, meaning that it is assumed the oil would be found in the process of looking primarily for gas.

The USGS assessment also found that about 18 trillion cubic feet of undiscovered gas are economically recoverable when the market price is $8 or more per thousand cubic feet, and 32 trillion cubic feet of undiscovered gas would be economic when the market price is $10 or more per thousand cubic feet.

There currently is no pipeline in place to transport gas from the North Slope of Alaska, so this assessment assumes that there is a 10- or 20-year delay between discovery and production in the NPRA. This analysis shows that if a pipeline is constructed, there is a significant amount of gas that is economically recoverable from the NPRA when prices are above $8 per thousand cubic feet of gas.

The different market prices quoted above for the same resource are because some resource accumulations are relatively easy to find and produce while others are not and therefore cost more.

"USGS estimates are based on 2010 costs and technology, and these results could change over time as they are dependent on multiple factors," said USGS scientist Emil Attanasi, who was the lead author for this assessment. "For example, USGS economic recoverability estimates could vary in the future depending on the timeframe and costs to construct a gas pipeline to the NPRA, technological advances that make resource extraction and development easier and less expensive, and fluctuating market prices for oil and gas."

The amount of oil that could be economically developed is significantly less than what the 2003 analysis concluded. One reason for the reduction is reduced volumes of technically recoverable oil based on recent NPRA exploration drilling which found gas rather than oil.

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