The Impact of Slickwater Fracturing Fluid Composition / Chemical Interactions on Membrane Fouling of Flowback Water

Although there is broad interest in the development of membrane systems for treatment of flowback water from natural gas production, there is currently little information on the critical components governing the fouling behavior of these complex fluids. Synthetic flowback water was generated by subjecting mixtures containing friction reducer, breaker, crosslinker and surfactants to the high pressures and temperatures associated with fracking operations in a 1 L Parr reactor that contained pulverized shale outcrops. Dead-end filtration experiments were performed to evaluate the impact of fluid composition and fracturing conditions on the fouling characteristics of flowback water during microfiltration (MF). Polyacrylamide (PAM) based friction reducer (FR) was found to be the most significant membrane foulant. Dynamic light scattering results suggested that the presence of breaker (ammonium persulfate) reduced the mean hydrodynamic diameter of PAM from more than 500 to 80 nm after activation with sodium tetraborate pentahydrate at high temperatures (80). This decrease in size led to a significant reduction in fouling during MF. The adsorption of organic additives within the shale formation during treatment in the Parr reactor was enhanced at high pressures (1200 psi), further reducing fouling by the recovered water. The addition of surfactants to the fracturing fluid led to the formation of a stable emulsion, which eliminated almost all of the fouling during subsequent MF treatment. These results demonstrate the significant interactions between various components used in hydraulic fracturing operations and its impact on membrane fouling, providing valuable suggestions on the development of efficient treatment strategies for flowback waters.