From Freshwater to High Saline Produced Water: Unlocking the Potential of Hydraulic Fracturing in Water-Scarce South Oman

Abstract The scale-up of multistage hydraulic fracturing in South Oman has intensified challenges related to sourcing sufficient fresh water. With approximately 8,000 m3 of water demand per well, the reliance on water haulage has led to extended standby times, increased operational costs, and production delays. This study explores the feasibility of using locally available high saline produced water—previously considered unsuitable for fracturing—to enhance operational efficiency while addressing freshwater scarcity. A comprehensive evaluation was conducted on various alternative water sources, including outputs from aquifer pump-off projects, wetlands, reedbeds, and deep-water wells, all were assessed based on volumetric capacity and logistical feasibility. Each source was assessed in laboratory to provide detailed chemical composition, and conduct scaling risks evaluation under simulated reservoir, production, and surface conditions when mixing with reservoir fluids. The study further explored the use of alternative chemical agents formulated to tolerate impurities, enabling the integration of these high-salinity water sources into fracturing operations. Initial compatibility tests identified different scaling risks in several water sources, leading to the selection of the most promising candidate for further evaluation. The standard slickwater formulations with high-viscosity friction reducers (HVFR) normally used for these multistage frac operations, were found to exhibit compromised rheological properties when mixed with the selected high saline water, thereby affecting proppant placement. This occurs because, the hydration of the polyacrylamide-based additive is compromised by the salinity of the mixing water. An alternative HVFR additive, specifically engineered for high salinity and impurity tolerance, was subsequently evaluated and approved. A field trial during the final stage of a well confirmed the operational viability of replacing fresh water with the produced water in multistage fracturing operations. The implementation of this technology has great benefits for the company and the country in terms of cost savings due to logistic and operations and allocating fresh water for human consumption only.