Comparative Study of Proppant Transport in the Vertical Fracture for High Viscosity Friction Reducers and Slickwater Fracturing with High-TDS Marcellus Shale Formation Water

Abstract

ABSTRACT High viscosity friction reducers (HVFRs) have been gaining more attention and increasing in use as proppant carriers. Reusing of produced water has also been driven by both environmental and economic benefits. However, high total dissolved solids (TDS) of produced water and high reservoir temperature significantly decrease the viscoelastic properties of HVFRs even for the cationic ones, which further reduce their proppant transport capabilities. Increasing loadings of HVFRs also has very limited effects on improving their proppant transport performances under high-TDS and high-Temperature conditions. The ultimate objective of this experimental study is to investigate the injection rate effects on the proppant transport performance of HVFRs, especially under high-TDS conditions. 1 gallon per thousand gallons (GPT) slickwater and 4 GPT HVFRs were comparatively analyzed by conducting rheology measurements and dynamic proppant transport experiments with both deionized (DI) water and 30,000 mg/L TDS Marcellus formation water at 60°C. The 1 GPT slickwater was injected at a rate of 1.5 gal/min, whereas the 4 GPT HVFR was injected at a lower rate of 0.75 gal/min. The results showed that HVFRs with low injection rates were preferred when using fresh water. In contrast, slickwater with high pumping rates was preferred during produced water fracturing. INTRODUCTION Over the past few years, the use of HVFRs in hydraulic fracturing has been increasing as they offer operational and economic benefits compared to traditional fracturing fluids such as slickwater and guar (Hu et al. 2018; Johnson et al. 2018; Biheri and Imqam 2021a). HVFRs have been found to lower operational costs, require less equipment, exhibit better conductivity in fractured formations, and lead to production improvements (Johnson et al. 2018; Ba Geri et al. 2019; Biheri and Imqam 2021b, 2022). However, hydraulic fracturing fluids are usually prepared using fresh water, which can be costly and present challenges when freshwater resources are scarce. As a result, the industry has been exploring the use of produced or formation water, which typically has high levels of salinity and hardness. Currently, most high TDS applications are focused on the Marcellus shale formation. The Marcellus shale is a Middle Devonian source rock and reservoir that spans over multiple states in the Appalachian Basin, including Kentucky, West Virginia, Ohio, Pennsylvania, and New York. This formation has an average temperature of around 140°F (60°C) and can reach bottom hole pressures up to 6000 psi. The produced and flowback water in this area has high levels of TDS, with a typical concentration range of 30,000 ppm to 50,000 ppm. (Williams et al. 2011; Johnson et al. 2018).