This post was written with Elena White, a Leadership Rice intern working with EDF's Energy Program this summer.
As drilling companies flood shale plays in North, South and East Texas, Texas farmers and municipalities are praying for rain. We have blogged about how water and gas are inextricably linked in hydraulic fracturing or fracing. But how much water is actually used? Can that amount be reduced? Today’s post is the first in a series of posts about hydraulic fracturing and how it impacts water resources.
How much water is used in fracing?
Fracing is the process of injecting water with fluid additives into a tight formation to open and enlarge fractures allowing the product to flow out. The water contains a proppant, such as sand, that remains in the fractures, keeping them open during the production phase. Water use varies from well to well depending on the nature of the shale formation.
According to Chesapeake Energy, the typical deep shale play use is between 4 to 6 million gallons per well or 0.8 – 1.6 gallons per MMBtu of energy produced. Proponents of fracing argue that the water amount per unit of energy in fracing is less than most other energy sources. Although this may be true, it is no consolation to a region with insufficient water to go around. Just like in real estate, the key is location, location, location.
This can create large issues in Texas, particularly because the oil and gas industry is regulated by the Railroad Commission, but water resource planning is the domain of the Texas Water Development Board. According to the Texas Water Code, oil and gas wells are exempted from regulation by groundwater districts meaning that although a district can limit pumping by an agricultural user, they may not have the tools to do the same to industry. Oddly enough, the Texas Water Development Board did not mention this in a recent message from Melanie Callahan, the Interim Executive Administrator, in which they advised readers to contact their districts for information regarding oil and gas water use. Further, the State Water Plan, upon which water planning decisions are based, does not even include oil and gas water projections in their fifty-year forecast. All of this means that we really don’t know what the impact of fracing will be on our water resources over the long term.
What about recycling?
Water usage for drilling is consumptive. Water removed from local sources and used for drilling or fracing will not return to the local water cycle. Once the water has been mixed with additives and run through the formation, the resulting produced water contains remaining chemicals as well as contaminants released from the parent formation. Some of the water remains in the shale, and about 10 to 40 percent resurfaces in the first few weeks.
Recycling can mean a couple of different things. It can mean that a large portion of the water is treated and made available to fracture additional wells. It can also mean that the water is treated and then returned to the normal water supply or to a surface water body. Some states, such as Ohio, have banned the latter practice because scientists are unsure whether traditional water treatment facilities are able to handle all of the contaminants contained in produced water. In many states, water that is not recycled or cannot be treated to a safe quality for release is injected deep below the surface for permanent storage.
Drilling companies in the Barnett Shale practice both of these techniques. The Texas Railroad Commission expects companies in the Eagle Ford and Haynesville shale plays to submit approval for similar recycling methods as drilling activity increases, particularly because water is becoming more expensive. However, recycling is no cure-all. Even with recycling, large amounts of water are necessary and it requires energy.
What are the water-energy trade-offs?
As in most energy related endeavors, there is a water component and visa versa and there are tradeoffs in this relationship. If you want to use less of one, you almost always need more of the other. Most of the water is used not in the fracing process, but in delivering the proppant. The more pressure behind the water, the less water is necessary. However, water pressure requires energy. Thus, yet again, we see how water use and energy are inextricably linked. We must make a decision between more surface energy use and using more water.
Recycling of the water can also have a large energy footprint. Produced gas is often used to power onsite treatment; however the quantity needed is not actually measured by gas companies. Energy needed would certainly fluctuate based on the content of the water. Higher concentrations of total dissolved solids would require more energy, particularly if the goal is to get the water to drinking water quality or “clean” enough to discharge into a surface water body. For all of these processes, decisions should be made based on local needs and limitations. Areas with low water availability may be willing to sacrifice more energy use for less water demand. Each region will be different and drilling should be tailored accordingly.