Experimental Study: Determine the Impact of Temperature on Proppant Settling Velocity Utilizing HVFR and Linear Guar
Authors: Biheri Ghith , Imqam Abdulmohsin 
Published: September 2022

ABSTRACT:
Fracture fluids play a significant role in providing good proppant distribution across the entire fracture network during hydraulic fracturing treatments. The objective of this research is to investigate the rheology properties of fracture fluids including the viscosity and elasticity parameters. The study also will determine the settling velocity of the proppant through fracture fluids using a static model. Two fracture fluids, high viscosity friction reducer (HVFR) and linear guar were selected to investigate the fluid rheology and proppant settling velocity at high temperature ranges. A 3 gpt concentration of HVFR and 30 ppt concentration of linear guar were studied at different temperature values (i.e., 25, 50, and 75°C). Four proppant sizes (i.e., 20, 30, 40 and 50 mesh size) were chosen to measure the proppant settling velocity at the mentioned temperature ranges using an unconfined static model. The results showed that HVFR has better viscosity and elasticity than linear guar, and higher suspension of proppant despite increasing proppant sizes. The study comprehensively investigated the settling velocity of the proppant using HVFRs in comparison to guar at various temperatures and how rheology of viscosity and elasticity of both fracture fluids can control the settling velocity of the proppant at high temperatures.

1. INTRODUCTION
Hydraulic fracturing techniques have been demonstrated to extract a considerable volume of oil from ultra-low permeability reservoirs, mainly in unconventional reservoirs (Ortega et al., 1996; Elturki and Imqam, 2020a; b; Khurshid et al., 2020). The permeability may even be reduced due partly to the deposition of organic compounds during oil production, such as asphaltenes and waxes, which may restrict the flow of oil, resulting in a decrease in oil production (Elturki and Imqam, 2021a; b; c; Mohammed et al., 2021; Elturki et al., 2022a; 2022b). Additionally, it is essential to analyze the injection and production rates data (Unal et al., 2019) and to evaluate the influence of pressure on fracture growth and geometry (Awad et al., 2020; Eltaleb et al., 2020, 2021) during hydraulic fracturing operations. Thus, to maintain the improvement of the oil wells productivity during hydraulic fracturing treatments (Elturki et al., 2021), the proppant should be distributed across the fracture length. This process of proppant transport can be conducted by a reliable fracture fluid that has good fluid rheology such as viscosity and elasticity. Several fracture fluids have been used in the field during hydraulic fracture operation like linear guar and crosslinked gels. Many studies have investigated the performance of the guar and crosslinked gels (Ihejirika et al., 2015; Saini et al., 2017). Their results showed that the guar and crosslinked gels was providing good viscosity especially at high fluid concentrations despite the presence of brine. However, the crosslinked gel and guar showed a large reduction in its viscosity as the injection pressure increases (Sanchez et al., 2015). Also, the impact of temperature on the linear guar and crosslinked gels was investigated in several studies (Barati and Liang 2014; Biheri and Imqam 2022). The results indicated that linear guar and crosslinked gels provide an acceptable ability to maintain lower temperature effect, but at high temperatures, these fracture fluids were impacted which may lead to reduce their effectiveness to provide better proppant distribution inside the fracture networks. In addition, these fracture fluids exhibit some problems during proppant transport; they need more equipment on the surface such as hydrating units and trucks, additional chemicals are required to provide good proppant transport, and these fracture fluids need more water. In addition, the traditional method of using linear guar or crosslinked gels shows acceptable capability to hold and transport smaller proppant sizes or lower sand loadings; However, its ability to transport proppant further inside the fracture networks reduces significantly as the proppant size or loadings increase. Recently, a new polyacrylamide fracture fluid known as high viscosity friction reducer (HVFR) has been used widely in North America during hydraulic fracturing treatments to transport proppant inside the network fractures. This fracture fluid (HVFR) provides environmentally friendly advantages, these advantages include reduced water amounts, a decrease in the use of chemicals by more than 30%, and minimized footprint on the location (Van Domelen et al., 2017; Dahlgren et al., 2018; Johnson et al., 2018). Moreover, the new product provides better proppant transport compared to linear guar or crosslinked gels even at larger proppant sizes or higher sand concentrations.