Innovative High-Salinity Water Based Fracturing Fluid for High-Temperature Applications: Reducing Freshwater Demand at Lower Cost

Abstract

Guar-based gel fluids are widely used in hydraulic-fracturing, because of salt resistance and high viscosity performance. To save freshwater usage, high salinity water was used as base brine for guar gel formulation. Different guar gum and guar derivatives including HPG and CMHPG were evaluated, in terms of molecular weight, hydration time and linear gel viscosity. Among all the tested samples, one CMHPG product was identified with hydration time less than 5 minutes and high linear viscosity s at 170 s-1 and concentration at 0.54 wt.% in high salinity water, which was used as the main component to formulate gel package. A high performance crosslinker system, including organic zirconium and TiO2 nanoparticles was developed, which showed excellent delayed crosslinking property. The guar gel formulation for high temperature of 300°F in high salinity water was developed with in-house synthesized crosslinker system. Based on the developed guar gel formulation, different additives, such as flow-back enhancer, biocide, clay stabilizer and encapsulated breaker were added into the gel formulation to test their effect on compatibility, rheology, gel breaking performance and formation damage restoration. A complete fracturing fluid package was developed with low polymer loading at 0.48 wt.%, which can maintain 300 mPa·s for 2 hours shearing at constant shear rate 100s-1 and 300°F, and at API standard shear sweep from 25 to 100s-1 and 300°F. The fracturing fluid package with encapsulated breaker can maintain high viscosity at 300°F for first 2 hours and break in the following 2 hours, which indicates good breaking performance. The broken fracturing fluid filtrate showed good regained permeability ratio at 86.1%. The above findings corroborate that the high salinity water-based fracturing fluid exhibited good viscosity, compatibility, shear resilience, effective breakage, and excellent retained permeability up to 300°F.