With the escalation of oil and gas production in the Utica and Marcellus shale plays, there is a growing awareness, and some concern, about the quantity of fresh water that must be used to enable production. Enormous volumes of water must be injected to depths often exceeding one mile to free up and produce valued hydrocarbons. But ironically, water already existing at those depths may eventually prove to be a matter of greater concern.
Given the necessary depths to reach oil and gas in these shale plays, the hydrofracking of a typical well can require anywhere from five million to eight million gallons of fresh water. These waters are formulated into fracking fluids with the addition of various chemicals and solids, known as proppants, which are designed to be pumped under pressure into fissures created in the shale layers in order to hold open and expand those fissures, allowing the release of oil and gas. Once the hydrocarbons are encountered and the well is ready for production, the bulk of these fracking waters return to the surface under pressure as flowback water and must be captured and contained due to their hazardous nature. Given the often challenging logistics of bringing high volumes of water to remote frack well sites, the oil and gas industry has vigorously pursued technologies that enable the treatment and re-use of recovered flowback waters. A recent study in West Virginia found that 81 percent of recovered flowback water was able to be recycled and re-used. In some instances, depending on the chemical formulation, flowback water has been recycled five and even six times when blended with additional fresh water. The “downside” to these many re-uses is that each re-use involves the addition of more fracking chemicals, and makes successful treatment of the flowback water less feasible.
Once flowback waters from the fracking process can no longer be treated or recycled, they must be disposed in Class II deep injection wells. Of the approximately 250 injection wells serving the Marcellus and Utica shale play region, approximately three-fourths of those wells are located in Ohio. Less than favorable geological formations make it difficult to site these wells in Pennsylvania and West Virginia. As a result, recent state records show that of the 12.2 million barrels of fracking waste and brine disposed in Ohio deep injection wells in the first half of 2012, 56 percent of those disposed materials came from Pennsylvania and West Virginia. The State of Ohio is closely monitoring its injection wells because of issues with seismic activity.
These injection wells are receiving not only flowback water from wells that are now being installed, but also “produced water”. Produced water is naturally occurring water, found in shale formations, that flows to the surface throughout the entire production lifespan of the well. Produced water is also typically hazardous, containing high levels of total dissolved solids, including barium, calcium, iron, and magnesium. It also contains dissolved hydrocarbons such as methane, ethane, and propane, along with naturally occurring radioactive materials (otherwise known as NORM), making it more challenging to recycle. Consequently, processing produced water typically involves the greater use of injection wells. Flowback water is typically recovered in a short, high volume spurt when a well is brought into production, usually over a matter of days. Produced water, on the other hand, is recovered over the entire period that the well is producing, flowing at a rate of two barrels to 40 barrels per day.
Data compiled by the Commonwealth of Pennsylvania indicates that the volume of flowback water generated from Marcellus wells in 2012 was about three times the volume of produced water. However, as more recently-developed wells go into production, the amount of produced water will increase, and the ratio will begin to change. While the volume of flowback water is expected to hold steady through 2019 at approximately 2.5 billion gallons per year, the amount of produced water is forecast to rise steadily over the next seven years until it surpasses the amount of flowback water in 2019 at 2.7 billion gallons. Data for the Utica play can be expected to follow a similar pattern, although on a delayed basis due to its more recent development.
This trend of increased volumes of produced water from Marcellus and Utica wells will be impactful on numerous fronts. First, it portends a high level of activity for Ohio’s deep injection disposal well network from both in-state and out-of-state generated waste waters over the coming decade. Second, the regulatory regime surrounding the disposal of mining waste waters will likely evolve and strengthen. Last, we will undoubtedly see new technologies and processes develop to treat both flowback and produced water.
For more information, please contact:
Theodore J. Esborn
Jeffrey R. Huntsberger
Michael L. Snyder
Michael W. Wise
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