All Active Wells as of October 2011 in the Marcellus Shale Formation of Pennsylvania

Data is sourced from the Pennsylvania Department of Environmental Protection. Map is designed to illustrate which counties in Pennsylvania have experienced the highest amount of oil and natural gas drilling activity. Actively producing well data is joined to individual counties to provide a count figure of active Marcellus wells within each area of interest. Data is provided as one record for each well drilled. The color gradient ending in dark red depicts counties with the highest number of drilled wells. The year 2005 is used as a baseline as this period represents the beginning of widespread natural gas drilling in the Marcellus shale formation which underscores much of Pennsylvania.