We have used a combination of experimental and computational methods to evaluate the performance of candidate green solvents as potential replacements for petroleum distillates. Measured and calculated physicochemical properties of the individual candidate solvents were used to perform initial screening. Properties of interest included the ability to suspend guar without swelling, and suitable viscosity of the neat solvent. The cost of using the candidates was then estimated, to eliminate candidates that would be too expensive to use in the field. The candidates with the most desirable properties were then down-selected for further testing.
The down-selected solvents were formulated with guar and hydroxypropyl guar to measure rheological properties of the suspension. Properties measured included pumpability under cold conditions and viscosity under high shear conditions. The formulations were then combined with water to understand viscosity of the aqueous solution under down-hole conditions. The results showed at least one candidate solvent which performed as well or better than the petroleum distillate control solvent. Additionally, the results showed the candidate solvents were able to control the rate at which hydroxypropyl guar increased viscosity in the aqueous solution.
The significance of this paper lies in its incorporation of known and predicted properties of green solvent candidates to perform the initial down-selection of chemicals for more extensive testing. This approach can simplify and expedite the process of developing new fracturing fluids which will have lessened environmental impact.