New HVFR Fluid Technology for Enhanced Proppant Transport in Varying Salinity Formations: An Unconventional Hydraulic Fracturing Application

A traditional fracturing job with slickwater has been a popular choice due to low fluid cost, ability to pump at high rates, and thus allowing for complex fracture geometry, as well as a high regained conductivity of created fractures. However, these fluids need a very high amount of fresh water to deliver a required amount of proppant because the proppant carrying capacity of low viscosity fluid is much lower. The biggest disadvantage in using slickwater is that produced water cannot be used as a fracturing fluid as the polymer is not hydrated properly and fluid stability is low in high salinity water. A high viscosity fluid like a guar or polymer gel can be used but the desired fracture complexity is hard to achieve, and significant formation damage is usually caused leading to low fracture conductivity. A High Viscosity Friction Reducer (HVFR) system is used as a specialized fracturing fluid to reduce friction within the wellbore while allowing for superior proppant transport. The reduced fluid resistance in the formation also helps to create wider, more conductive fractures with more efficient placement of proppant. In this work, a new HVFR system is developed that can be customized for given water quality, with a wide range of total dissolved solids (TDS) values. This provides a flexibility to design fracturing jobs in unconventional reservoirs based on field conditions. During the development of this fluid, extensive laboratory testing of fluid rheology and performance was done. Friction reduction of the HVFR fluid system was measured for varying TDS values and it was found that friction reduction was >70% for both fresh water and high TDS water (>200,000 ppm) cases. In addition, the hydration rate of the polymer was found to be very fast (<0.5 min). The fluid viscosity profiles as a function of shear rate (3-600 rpm) and HVFR concentration (1-8 gpt (gallon per thousand gallon)) were also established. It was found that viscosity values varied from 700 – 250 cP as the shear rate increased from 3 to 600 rpm for HVFR concentration of 8 gpt. Because of the unique chemistry of the HVFR polymer, even high concentrations (>4 gpt) were found to be cost-effective solutions. The HVFR system developed was used in several horizontal wells using flowback water. It was found to perform exceedingly well for high TDS water as compared to other fracturing fluids available.