Most oil and gas wells bring waste fluids during production. For an oil well this is produced water, or brine, brought to the surface with the oil. For many oil wells the amount of this waste fluid is equal to or more than the oil in terms of volume.
Natural gas well waste fluid is more complex. It is typically produced water (brine) and/or crude petroleum. The crude petroleum can be a low octane gasoline like product (condensate) or a much heavier oil.
For oil and gas producers waste fluids have to be disposed of and the commonest method is underground injection in a specially constructed and permitted Underground Injection Control well. Crude petroleum has a value and is retained and sold.
The chemical characteristics of produced water vary according to the well's formation and well's location. This produced water is remnants of ancient seawater and is extremely "salty." The high chloride concentration is an identifying marker.
The chemical characteristics of crude petroleum are also variable and are measured through Total Petroleum Hydrocarbons, gasoline range and/or diesel range. Extremely toxic components of petroleum like benzene are measured separately. A high benzene concentration in fluid is an indicator of petroleum.
Produced water from the Devonian shale formations, including Marcellus, can have high radium 226 and 228 concentrations along with high chloride and barium. In contrast, produced water from coalbed methane wells is characterized by relatively low chloride, barium, petroleum components and radium.
Proper well construction and waste fluid storage and transfer are essential in order to prevent contamination of soil, surface and ground water due to exposure to produced fluids.
While there are published sources which give an idea of the ranges of chemical concentrations for West Virginia brines, the best source of information can be found in Class IID UIC permit applications which are required to have chemical analysis of the injection fluid. Most often these permit application fluid analyses are based on samples taken from tanks or pits; there are times when the sample is taken from a single well's fluid.
To help get an idea of the range of chemical concentrations in comparison with their primary Maximum Contamination Levels for drinking water established by the EPA (and secondary MCLs which primarily affect taste or color of drinking water) is presented on this table derived from sampling of waste pits at two injection well sites. The Ritchie county UIC well (2D08509669) is waste from Marcellus shale wells in the north of the state. The Fayette county UIC well (2D01900460) is waste from a variety of formations from wells in and out of state. Waste at both sites has high chloride and barium concentrations. The Ritchie county well's lab analysis shows high radium 226 and 228 in a ratio typical of Marcellus shale waste. For more about Naturally Occurring Radioactive Materials (NORM) see this USGS brochure.
As comparison, examine this laboratory analysis for an injection well in the south of the state in Wyoming county (2D10902703) which disposes of coalbed methane well waste. (Note that this analysis shows results in micrograms per liter -- ug/l, compared to the table's results in milligrams per liter -- mg/l. A microgram is a thousandth of a milligram, divide the laboratory's results by a thousand to convert the results to milligrams. The report's chloride at 2790000 ug/l is equal to 2,790 mg/l, appreciably lower than the concentrations on the table.) For help in looking at lab reports go to this page.
Here are some links to laboratory analyses in UIC permit applications. This Upshur county well's lab results are found on pages 91-93 and 139 (the latter is the radiological analysis) of the permit application for 2D09703737. Lab results for 2010 and 2015 are found for this Pleasants county commercial well (2D07302523) in their permit application (2010 -- pp 120-129; 2015 -- pp 176-177). This Kanawha county's well (2D03902419) lab results in their permit application (pp 150-151) show high TPH and benzene which seems to indicate fluids from oil wells.
Permit applications for injection wells disposing of oil and gas waste, including produced fluids, and other information about particular wells can be found on this page in the UIC section of this site.
Periodically UIC permit applications have the laboratory analysis for a single oil or gas well's produced fluid as an example of the fluid being disposed of. This is the analysis for a well in Kanawha county, 47-039-06053, which is producing fluids from four formations, Berea sandstone, Lower Huron shale, Rhinestreet shale, and Marcellus shale. Note the extremely high concentration of chloride, comparable to about four pounds of table salt per gallon of water. Unfortunately the analysis didn't also cover other constituents of concern such as barium.
One type of produced fluid is hydraulic fracture fluid flowback. This is waste fluid that returns to the surface after hydraulically fracturing a well. For a horizontal well with numerous fractures this fluid volume can be substantial. The fluid is a combination of the fluids injected deep underground and underground fluids freed during fracturing. The WV Department of Environmental Protection analyzed the fluid produced from a Marcellus shale horizontal natural gas well in Wetzel county in 2009 over a period of time. This analysis shows the transformation over that period of chemical concentrations from flowback to produced fluids. The chloride, barium, and petroleum components (TPH gasoline range and BTEX chemicals) all dramatically increase in concentrations. A similar increase is seen in the radiological chemistry, radium 226 and 228.
Produced fluids can be very toxic to the environment and to humans, can adversely affect surface and ground water quality, and, when there is a petroleum component along with trapped methane gas, can be explosive. Proper materials handling during transfer, storage, and storage is essential.
Gas Well Site Visits
Gas Well Study is the examination of natural gas wells in West Virginia.
Underground Injection Control Class 2 Wells
These wells are used either for the disposal of oil and gas liquid waste or for the enhanced recovery of oil or natural gas.
Gas Well Study Site Visits
Annual reports, environmental assessments, and individual well information.
Select videos from the Gas Well Study YouTube channel.
What Happened at Fernow
An investigation into what caused the vegetation death in the land application area after landspraying hydraulic fracture flowback waste.
The Spill at Buckeye Creek
An investigation into a spill from a Marcellus well site into Buckeye Creek in Doddridge county.