During hydraulic fracture operations, fracture fluids play a critical role in carrying the proppant in fracture networks, which aims to obtain better oil productivities in unconventional reservoirs. The main objective of this work is to evaluate the rheological properties of high viscosity friction reducer (HVFR) in comparison to traditional guar linear gel fracture fluids. Two types of HVFRs (anionic and cationic) were also used for further rheological measurement analysis. The first section of the study sought to determine the effect of the fluid concentrations of both HVFRs and guar-based fluid. The second part was conducted to investigate the impact of temperature on the rheology parameters of anionic HVFRs and guar. The last section was performed to study the rheological performance of the use of anionic HVFRs in comparison to the cationic HVFR type. The results showed that HVFR provided better viscosity and elasticity than linear guar even at a higher fluid concentration. Also, HVFR exhibits a higher resistance of temperature, which was clearly noticed at a temperature below 75 °C, while guar did not show any resistance of temperature even at 50 °C. This work provides comprehensive knowledge that can help to estimate proppant transport in unconventional reservoirs.

1. Introduction

In unconventional reservoirs, fracturing fluid is one of the main parameters that improve the formation of shale permeability during hydraulic fracture treatments. This improvement could be provided by the transport of proppant farther across the fracturing networks. Linear guar and crosslinked gel have been used as fracturing fluids to transport sand; guar and crosslinked gels have provided a good distribution of sand across the fractures, especially when smaller proppant sizes or lower sand loadings are used (Kim et al. 2021). However, they exhibited some issues. For example, they could not suspend and carry proppant at larger sand sizes or higher proppant loadings. Also, the use of linear and crosslinked gels requires more water, chemical materials, and footprint equipment at the location when those used to prepare the sand mixtures (Dahlgren et al. 2018; Johnson et al. 2018; Van Domelen et al. 2017). Furthermore, guar and crosslinked gels showed operational problems like sand may not transport further and started to gather near wellbore, which may lead to an increase in pumping pressure (Hu et al. 2018; Biheri and Imqam 2020).

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