ABSTRACT
In this chapter, an experimental and modeling work is presented where proppants and natural minerals were tested to study the transport behavior of alkaline earth elements in produced water. In all cases, no retardation of the ions was observed at the salinity conditions of the produced water, but strong retardation in the pH front was measured, indicating that adsorption indeed occurred. When using manganese oxide and upon dilution of produced water, the concentration fronts of all major divalent cations were retarded. However, a fast traveling pulse formed due to the combined effect of pH-dependent solute transport and hydrodynamic dispersion. This phenomenon confirmed that significant adsorption occurred under those conditions. But, pH-dependent adsorption and hydrodynamic dispersion can favor fast solute transport. A reactive transport model was developed and implemented in PHREEQC to describe these results. It agrees well with the data. This opens the possibility for the application of the model to design a reactive MnO2-based material to mitigate the potential negative impact of produced water spills on potable shallow aquifers.
