Fracking

Hydraulic fracturing depends on injecting fluid under sufficient pressure to create or enlarge fractures in the target formation. Proppant, commonly sand or another solid material, is carried into those fractures to help keep them open after pumping pressure is reduced. Treatment records can therefore show how individual stages were executed and whether the documented fluid volumes, proppant quantities, pressures, and rates correspond with the planned treatment.

The analysis can compare the water and additives injected during treatment with fluids returning to the surface, their timing and volumes, handling records, storage, transportation, reuse, or disposal. Because produced water can include both returned hydraulic-fracturing fluid and naturally occurring formation water, those sources may need to be distinguished when they are material to the dispute. EPA treats produced-water handling and wastewater disposal or reuse as distinct stages of the hydraulic-fracturing water cycle, along with water acquisition, chemical mixing, and well injection.

The hydraulic-fracturing operation should be distinguished from later wastewater-disposal activity. Hydraulic fracturing can induce earthquakes under some conditions, but USGS reports that wastewater injected into deep disposal wells is much more commonly associated with felt induced earthquakes because disposal operations generally inject larger volumes over longer periods. A dispute involving seismicity may therefore require review of both the fracturing record and any separate wastewater-injection history, with seismology expertise added when the earthquake evidence itself is central.