Wastewater that comes to the surface after a well is fractured contains chemicals used in fracturing
and the products of the reactions of those chemicals. The fracturing fluid that flows back is similar in chemical composition to the fracturing fluid pumped down the well, but it is not identical. They are not identical because chemicals in fracturing
fluid can break down, interact with each other, or interact with chemicals in the target formation. These
interactions decrease the amount of the chemicals originally added to the fracture fluid. They also create
chemical compounds not originally present in the fracturing fluid