What is wastewater?
When a well is fracked, large volumes of water are pumped into the well. This water contains about 1% of added chemicals that aid in getting the oil and gas out of the shale. In a well using 4.2 million gallons of water, 1% of this is 42,000 gallons of added chemicals.
Fluids that come back out of a well after it has been hydrofracked are called wastewater. Wastewater includes both flowback fluid and produced water.
Flowback fluid is similar in composition to the hydrofracking fluid that is pumped down the well to frack the shale.
Produced water is water that has been in contact with the shale formation much longer than the flowback fluid, therefore, containing salts, heavy metals, and naturally occurring radioactive material.
What happens to the wastewater?
Dealing with such large quantities of wastewater is challenging.
Wastewater from HVHF can be legally disposed of in one of three ways:
- Recycling treatment in an approved wastewater treatment plant
- Treatment in an out-of-state treatment plant
- Placement in an underground injection well
Most produced water from oil and gas production in the U.S. is disposed of in injection wells.
The use of injection wells for disposal of industrial waste is more common in the western U.S.
How is wastewater disposal related to induced seismicity?
