Coalbed Methane in the United States: A GIS Study, by Samuel H. Limerick, #10066 (2004).

*Adapted from a poster presentation at AAPG Annual Meeting, Dallas, Texas, April 18-21, 2004.

A map of coalbed methane (CBM) gas field outlines in the US was built using ESRI ArcGIS software. The field outlines are displayed on a background of USGS and Alaska DNR coal basins along with active and abandoned coal mines. Inset maps show details of the 10 most active CBM basins. Well data for the field outlines was obtained from 18 state geological surveys or oil and gas commissions. Field outlines were constructed by buffering the wells from each field with a radius based on their spacing, then unioning the buffers to make a single polygon record per field name. A visual basic applications program within ArcGIS was used to automate the buffering process (necessary with >35,000 wells and > 350 fields).

CBM past production (from the state oil and gas commissions), present proved reserves (Energy Information Administration [EIA]) and future resources (Potential Gas Committee) were classified by basin and displayed as chloropleth maps and pie charts. Comparison of these shows the decline in relative contribution over time of the San Juan and Black Warrior Basins and the ascent of the Powder River Basin.

Specific emissions (annual gas emitted / coal produced) of the EPA’s 121 gassiest active coal mines were calculated and mapped. The greatest number of gassy coal mines is located in the Appalachian basin, while the Black Warrior Basin has the highest mean specific emissions.

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