(515d) Novel pH-Switchable Viscosity Modifiers to Improve Rheology and Cost Efficiency of Hydraulic Fracturing Fluids

The composition of the fracturing fluid used during hydraulic fracturing plays an eminent role in determining the efficacy of the process. Being able to design fluids that carry proppants with enough driving force into fissures while keeping costs low has become an interesting research problem.

Herein, we report a simple formulation based on the dynamic binary complexation of a long chain acidic compound and triamine. At low weight percentages (<2.5%) of the mixture in water, we report large viscosities of the solution in certain pH ranges, at high shear rates. Changes to the pH reduces the viscosity once again, creating an easily switchable system. This in turn will further enable change of the settling velocity of sand and other proppant particles by a few orders of magnitude by simply controlling the pH. Particle settling tests were deployed to investigate this. Several other tests were also conducted to gain a better understanding of the interfacial phenomena involved in the system, as well as to facilitate rheological predictions. Furthermore, the effects of temperature and salinity on the properties of the mixture were investigated to compare it to real world conditions, such as those observed in major shale basins across the USA.

In summary, there is tremendous potential for the use of such supramolecular formulations in the hydraulic fracturing space. They may go a long way in producing a cost-effective solution to some of the key issues that currently plague this domain such as cost, sustainability, recyclability, etc.