Updated geological maps provide more details about the Marcellus formation – Today in Energy

April 1, 2015

Source: US Energy Information Administration, based on DrillingInfo Inc., New York State Geological Survey, Ohio State Geological Survey, Pennsylvania Bureau of Topographic & Gelogic Survey, West Virginia Geological & Economic Survey and US Geological Survey
To note: The map includes production wells from January 2003 to December 2014. Click to enlarge.

Natural gas production from the Marcellus shale formation in the Appalachian Basin increased to 14.4 billion cubic feet per day (Bcf / d) in January 2015, accounting for over 36% of shale gas production and more than 18% of the total production of dry natural gas. in the United States, according to the EIA Weekly update of natural gas. Recent updates to EIA maps and geological information for the Marcellus Shale area help characterize the structure, thickness and extent of the formation.

The EIA uses well data to construct maps showing the extent and structure of the formation of productive and potentially productive regions of Marcellus. Structure and thickness maps are key elements in resource estimation and in defining areas where hydrocarbon extraction is economical. Maps showing the top and bottom of the formation as 3D surfaces can be used for a rough estimate of subterranean volumes, as well as for the detection of regional structural and tectonic features such as major faults, folds and overlaps.

3D image of the Marcellus formation, Appalachian basin, as explained in the text of the article


Source: US Energy Information Administration, DrillingInfo Inc., New York State Geological Survey, Ohio State Geological Survey, Pennsylvania Bureau of Topographic & Gelogic Survey and West Virginia Geological & Economic Survey
To note: The figure shows a three-dimensional image of the top surface of the Marcellus Formation.


To generate formation structure and thickness (isopach) maps, the EIA uses stratigraphic correlations provided by state geological survey agencies based on data from 2,416 wells. Marcellus currently produces in four states: Pennsylvania, West Virginia, Ohio and New York. Because hydraulic fracturing had effectively been suspended (and more recently banned) in New York City, natural gas production in New York mirrors production from wells drilled before 2010.

The Middle Devonian Marcellus Shale stretches from New York in the north to Kentucky and Tennessee in the south and is the most prolific natural gas producing formation in the Appalachian Basin. The formation and play footprints cover approximately 95,000 square miles and 72,000 square miles, respectively. The Marcellus Formation consists of several sublayers which are grouped together in the lower and upper intervals of Marcellus. Lower Marcellus has a significantly higher organic matter concentration than Upper Marcellus.

The summit of the Marcellus Formation has an elevation of 1,000 feet to 8,000 feet below sea level (or about 100 feet to 9,900 feet below the surface) and produces mainly natural gas in northeastern Pennsylvania , but becomes richer in liquids (yields lower or lower natural gas-to-oil ratios) in the less thermally mature regions of southwestern Pennsylvania, West Virginia, and southeastern Ohio. Thermal maturity reflects the temperatures to which the bedrock has been exposed over geological time. The parent rock produces hydrocarbons only in a limited temperature range.

As the structure map and the 3D image show, the Appalachian Basin is an asymmetric depression. The depth of the Marcellus Formation gradually increases from northwest to southeast with steep uplift along the western edge of the Appalachians, where the formation is exposed to the ground surface. Most of the producing wells are located in areas where the formation’s submarine depth is 2,000 feet to 6,000 feet below sea level.

thickness map of the Marcellus formation, as explained in the text of the article


Source: US Energy Information Administration, DrillingInfo Inc., New York State Geological Survey, Ohio State Geological Survey, Pennsylvania Bureau of Topographic & Gelogic Survey and West Virginia Geological & Economic Survey
To note: The map includes production wells from January 2003 to December 2014. The Isopach lines represent the thickness of the formation with a contour interval of 50 feet. An additional 25 foot isopach is shown as a dotted line on the western edge. Click to enlarge.

The Marcellus Range is up to 950 feet thick and generally shows a decrease in thickness westward from the central part of the basin and pinches in the subsurface along its eastern boundary. The thick and potentially gas-rich gap extends southwest in an arc through New York, Pennsylvania and West Virginia and runs parallel to the western edge of the Appalachians. Most of the current production is located in areas where the formation thickness is greater than 50 feet.

The Marcellus is one of many oil and natural gas formations with updated geological details. Earlier this year, the EIA updated the geological maps for the Eagle Ford game in Texas. In addition, EIA has released updated shapefiles for the following coins: Abo-Yeso, Bone Spring, Delaware, Glorieta-Yeso, and Spraberry; Bakken and three forks; Eagle Ford; Marcellus; and Niobrara.

Main contributors: Olga Popova, Evan Frye, Elizabeth Panarelli


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