Oil and Gas Related Studies
Water Resources and Natural Gas Production from the Marcellus Shale [USGS Fact Sheet 2009-3032]
Natural Gases in Ground Water near Tioga Junction, Tioga County, North-Central Pennsylvania - Occurrence and Use of Isotopes to Determine Origins, 2005 [USGS Scientific Investigations Report 2007-5085]
An inventory of combustible-gas concentrations in headspaces of water samples from 91 wells showed 49 wells had water containing combustible gases at volume fractions of 0.1 percent or more. A subsequent detailed gas-sampling effort focused on 39 water wells with the highest concentrations of combustible gas (12 representing the outwash aquifer and 27 from the bedrock aquifer) and 8 selected gas wells. In water-well samples, methane and ethane were the only hydrocarbons detected at reportable concentrations. Methane concentrations as high as 44.8 mg/L (milligrams per liter) were measured and methane concentrations were greater than 25 mg/L in 38 percent of the 39 samples. Proximity to the axis of the Sabinsville Anticline and the eastern margin of the gas-storage field correspond to the presence of thermogenic gas in water wells. Of the water-well gases with a thermogenic signature, about half are from outwash-aquifer wells and half from bedrock-aquifer wells. Of the bedrock-aquifer-well gases with a thermogenic signature, the majority are from wells drilled into bedrock beneath the Tioga River valley. The microbial gases were found chiefly in bedrock-aquifer well waters; 10 water wells representing upland and valley settings were along the northern flank of the Sabinsville Anticline.
Ground-Water Resources and the Hydrologic Effects of Petroleum Occurrence and Development, Warren County, Northwestern Pennsylvania [USGS Scientific Investigations Report 2006-5263]
The development of groundwater in Warren County for domestic and municipal use has been difficult because of very shallow petroleum reservoirs in parts of the groundwater system. In Pleasant Township, a major subsurface natural gas migration in 1983 resulted in high concentrations of natural gas observed in water wells, a spring, lake, and tributary stream of Chapman State Park. Although natural gas concentrations in groundwater diminished over time, several wells continued to experience severe natural-gas contamination in 1986. A well containing water that was saturated with natural gas was reported to have exploded, and another well suddenly discharged water from a vent pipe after pumping. Samples from wells in this area had elevated levels of arsenic and barium. Thirty-two of 68 samples collected in this area equalled or exceeded the USEPA MCL of 10 μg/L for arsenic. Barium concentrations ranged from 40 to 1,660 μg/L but were below the USEPA MCL of 2,000 μg/L. It is not known if these elevated concentrations were the result of gas migrations, but the concentrations were higher than those reported for samples collected from other wells in the county that draw water from the same hydrogeologic units.
A Feasibility Study to Estimate Minimum Surface-Casing Depths of Oil and Gas Wells to Prevent Ground-Water Contamination in Four Areas of Western Pennsylvania [USGS Water-Resources Investigations Report 87-4136]
Because of the poor quality and scarcity of groundwater data, the altitude of the base of the fresh groundwater system in the four study areas cannot be accurately delineated. Consequently, minimum surface-casing depths for oil and gas wells cannot be estimated with confidence. Conscientious and reliable reporting of freshwater and saltwater during drilling of oil and gas wells would expand the existing data base. Reporting of field specific conductance of groundwater would greatly enhance the value of the reports of groundwater in oil and gas well-completion records.
Ground-Water Resources Data for Warren County, Pennsylvania [USGS Open-File Report 94-87]
Report contains data on dissolved methane, ethane, and propane in groundwater.