Changes

===Methane in Aquifers:===

===Methane in Aquifers:===

* EPA draft assessment of the potential impacts of oil and gas hydraulic fracturing activities on the quality and quantity of drinking water resources in the United States released in June 2015. Read executive summary or full report.   

* EPA draft assessment of the potential impacts of oil and gas hydraulic fracturing activities on the quality and quantity of drinking water resources in the United States released in June 2015. [http://www2.epa.gov/hfstudy/executive-summary-hydraulic-fracturing-study-draft-assessment-2015 Read executive summary or full report].   

* Science Advisory Board Hydraulic Fracturing Research Advisory Panel has released two preliminary reports as part of its public meetings and peer review.  

** Science Advisory Board Hydraulic Fracturing Research Advisory Panel documentation of its public meetings and peer review is [https://yosemite.epa.gov/sab/sabproduct.nsf/fedrgstr_activites/HF Drinking Water Assessment!OpenDocument&TableRow=2.2#2. here].

* A geochemical context for stray gas investigations in the northern Appalachian Basin: Implications of analyses of natural gases from Neogene-through Devonian-age strata, Fred J. Baldassare, AAPG Bull. V. 98, No. 2 (February 2014), P. 341–372. Thermogenic and microbial gases occur in shallow aquifers and formations above the Marcellus, and predate Marcellus drilling.

* Methane and other gases occur in shallow aquifers and formations above the Marcellus, and predate Marcellus drilling: ”A geochemical context for stray gas investigations in the northern Appalachian Basin: Implications of analyses of natural gases from Neogene-through Devonian-age strata”, Fred J. Baldassare, AAPG Bull. V. 98, No. 2 (February 2014), P. 341–372.  

* Methane found in water wells in the Denver-Julesburg basin, Colorado, is mostly microbially generated in shallow coal seams. About 0.06 to 0.15 percent of wells leaked thermogenic methane due to inadequate surface casing, casing leaks or wellhead-seal leaks ([http://www.pnas.org/content/early/2016/07/05/1523267113.full.pdf Owen Sherwood and others, 2016]).

===Methane Air Emissions: there is significant variation in measured, estimated or modeled values:===

===Methane Air Emissions: there is significant variation in measured, estimated or modeled values:===