Thesis or dissertation
Date of this Version
While exploitation of the Marcellus Shale constitutes a major economic opportunity for leaseholders and the state of Pennsylvania, it also has brought persistent concerns over the environmental and economic impacts this may have on air and water quality, forest health, property values, and wildlife. This project examined 3 specific aspects of natural gas related activity in 9 watersheds of various drilling intensities in north-central Pennsylvania. The impacts of gathering pipeline in particular were examined, including their role in forest fragmentation, the energy return on investment (EROI) associated with their construction, and how this energy return was distributed over the well’s lifetime to date. The results revealed that gathering pipelines likely caused minimal losses in forest cover from 2005 to 2010 in 4 of the 6 sites featuring drilling activity. Losses could be attributed to pipelines even in high intensity sites that initially had less forest cover than the low intensity sites. The EROI of pipelines included both their embodied energy and their construction costs, and was found to constitute less than 3% of the energy return, given three different scenarios of EROI analysis in which wells of a low (1.3 trillion Btu) or high (2.6 trillion Btu) lifetime productivity were compared to energy costs of pipeline lengths with three different diameters (12, 20, and 24 inches). Finally, reporting data obtained from the state Department of Environmental Protection was analyzed to produce decline curves for 54 wells in Susquehanna and Bradford counties. Fifty of the wells reached their maximum production within a year of being drilled, and by the wells’ second reporting periods (an average of 546.98 days after completion), 31 of the 46 applicable wells were producing less than half of their maximum. The study revealed that drilling activity in the area is proceeding according to the high development scenario projected by The Nature Conservancy, but that space between pads and total pipeline lengths is smaller than initially predicted.
The results suggest that increasing the number of wells on a well pad is key to a number of improvements. Forest fragmentation as well as impacts on biological communities would be minimized with fewer disturbances and less pipeline. This would require drillers to consolidate leases, but would also result in a smaller investment of energy in pipelines. Municipalities should be aware that gathering lines may open up “highways” of drilling activity and should be allowed to maintain their zoning rights. Finally, multiple wells per pad would ameliorate the replication of impacts sacrificed for what could be a lifetime far less than the 40-50 years suggested by drilling advocates.
Date Posted: 24 July 2014