Performance Evaluation of Seawater-Based Fracturing Fluid with High-Viscosity Friction Reducer and Different Polymers

Abstract

Hydraulic fracturing, especially when employing water-based fluids, demands a substantial amount of water resources. Given the scarcity of freshwater sources in Saudi Arabia, the utilization and transportation of freshwater for hydraulic fracturing operations have become excessively expensive. Since 2012, efforts have been underway to explore the feasibility of utilizing seawater (SW) as the main component for fracturing fluid in Saudi Arabia. The paper aims to utilize seawater to replace freshwater as the base fluid in slickwater. The study conducted a total of 22 experiments comparing DI water-based slickwater and seawater-based slickwater in different High Viscous Friction Reducer (HVFR) concentrations. After selecting the HVFR concentration with the best rheological performance in seawater, two polymers which are HPG and CMHPG were tested before the addition of Zr-Crosslinker using Anton Paar-MCR 702e high-pressure, high-temperature (HTHP) Rheometer under a consistent pressure of 500 psi, a shear rate of 100 1/s, and varying temperature conditions (70°C and 120°C). In the first part of the study, different concentrations of HVFR were tested in both DI water and seawater (SW) at 70°C and 120°C. In SW, at 70°C, two of the concentrations showed promising results, while at 120°C, neither concentration maintained reliable viscosity. Conversely, all concentrations performed well in DI water. After adding the two polymers, HPG showed decreasing stability at higher temperatures in DI water. In contrast, at elevated temperatures, CMHPG exhibited greater stability compared to HPG and generally demonstrated higher viscosity. It was observed that in DI water, HPG is always the dominant polymer. On the other hand, in SW, at lower temperatures, HPG outperforms CMHPG in terms of viscosity and stability. However, at higher temperatures, CMHPG is the better polymer. Additionally, after adding the Zr crosslinker, viscosity and stability were improved for both polymers. This paper presents novel insights into the utilization of seawater as a base fluid in slickwater hydraulic fracturing operations in Saudi Arabia. By comparing the rheological performance of seawater-based slickwater with freshwater-based slickwater, and exploring the effectiveness of different polymers and crosslinkers in seawater environments, this innovative strategy offers significant potential for economic savings while promoting sustainable water management practices in the petroleum industry.