Optimization and Analysis of Holistic Wastewater Reusing and Treatment Strategies in Shale Gas Hydraulic Fracturing: A Case Study in Sichuan, China

Abstract

With the evolution of hydraulic fracturing technology, shale gas development in China’s Sichuan region has become commercialized and highly active. This process consumes a substantial amount of water, currently primarily sourced from rivers and the direct reuse of flowback water. However, there is a lack of systematic water resource management, leading to high water usage per well and potentially significant adverse impacts on the regional ecosystem. This paper proposes an optimization-based water management model for shale gas development, focusing on total dissolved solids (TDS) as the key pollutant. The model considers three wastewater treatment methods: onsite treatment, commercial treatment centers, and reinjection wells, along with wastewater reuse among well pads. The model accounts for geographic factors, treatment capacities, and wastewater composition, ensuring a comprehensive approach to wastewater management in shale gas development. A case study was conducted on three well pads in the Weiyuan shale gas block in Sichuan. The results show that onsite desalination and wastewater reuse between well pads can significantly reduce water management costs and freshwater consumption. Due to geographic factors, such as the mountainous terrain and distance from existing treatment facilities, commercial treatment centers and reinjection wells are not suggested. The average optimized single-well freshwater consumption in Weiyuan is 15,078 m³, which is comparable to the Eagle Ford site’s average of 16,100 m³ in Texas, USA, but significantly lower than the average of 24,415 m³ in Sichuan.