Methane has been identified in drinking water wells and/or the basements of homes in Pennsylvania and other places. Some have loudly claimed that the mere presence of methane is proof that hydraulic fracturing for natural gas has contaminated water supplies and put people at risk. Others have begun to research the potential sources of stray gas methane and have arrived at a different, more scientifically based, explanation. In doing so, they have raised a new concern which may foster a wave of litigation against oil and gas drillers and operators.
Methane is an odorless and colorless gas and is the primary component of natural gas. Stray gas methane is a natural hydrocarbon which has migrated for various reasons from its original location in the subsurface into the atmosphere, shallow groundwater, drinking water supplies, or enclosed spaces. Stray gas methane is of two types: thermogenic or biogenic. Thermogenic gas is formed during the ancient deposition of organic material and its subsequent heating through pressure. Although mostly methane, it also includes ethane, propane, and butane. It is commonly associated with subsurface oil and gas deposits. Biogenic gas is almost all methane, is formed by microbial fermentation of organic matter in the near surface, and is not associated with oil and gas deposits.
The presence of methane in a drinking water supply or an enclosed space does present some level of risk to those exposed to it. Several movies condemning hydraulic fracturing depict people lighting fires from their hoses or kitchen sinks. Obviously, no one wants to drink water that has such levels of methane. Further, when present in an enclosed space, such as a basement, the stray gas methane presents a real risk of explosion (the lower explosive limit for methane is 5% by volume) and depletion of oxygen supply.
Identifying the source of stray gas methane has become critically important. In some situations, the methane may be naturally occurring due to normal movement through permeable subsurface formations. It is well documented that methane existed in water supplies prior to any hydraulic fracturing in Pennsylvania. Analytical tests are usually performed to determine whether the methane is biogenic (almost all methane) or thermogenic (includes other substance, such as ethane, associated with oil and gas). A finding that the methane is biogenic suggests that oil and gas activity is not involved.
Nevertheless, oil and gas activity can create stray gas methane. The well will be drilled through multiple formations, some of which may have methane within them. An improperly cased, sealed, or plugged well may allow this gas to migrate upwards and into shallow groundwater, which may then contaminate a drinking water supply. It is important to note, however, that to date, there are no definitive reports of fracturing creating stray gas; instead, poor casing, sealing, or plugging have been identified as the cause.
Clearly, this raises liability concerns for drillers and operators. In some situations, the responsible parties are easily identified. For example, in Bainbridge Township in Ohio, a gas well was drilled but a poor cement job allowed gas to migrate upwards into an overlying aquifer. The stray gas contaminated several water wells and entered a basement, causing an explosion that damaged the foundation. The parties settled the resulting lawsuit.
The Bainbridge incident could have been avoided through better quality control. However, there are hundreds of thousands of wells that have been drilled in decades past that were plugged and abandoned (presumably) in conformance with the standards at that time. The location of some of these wells has been lost and homes may have been built over or around them. Even assuming that the wells were all properly plugged and abandoned in an era without much regulatory oversight, the materials of construction used at the time will reach the end of their useful life, allowing methane to creep upwards and potentially contaminate water supplies and enter enclosed spaces. These old wells may be creating a risk which could lead to personal and property damage.
As noted above, litigation against the drillers and operators over stray gas methane in water supplies and enclosed spaces has begun. While litigation against the driller and operators of older wells presents obstacles, such as finding viable parties, stray gas methane from these sources may open a new chapter in litigation against oil and gas drillers and operators.