Toward sustainable treatment: Life cycle assessment-based optimization of shale oil fracturing flowback fluid process in the Songliao Basin

The pursuit of shale oil has become a strategic imperative for global energy security, yet the massive generation of shale oil fracturing flowback fluid (SOFF) poses severe environmental challenges due to its complex chemical composition. While integrated treatment trains centered on Reverse Osmosis (RO) technology have emerged as a promising solution for high-quality on-site reclamation, their holistic environmental sustainability remains insufficiently understood. Based on 2025 annual operational data, we conducted a comprehensive life cycle assessment (LCA) of a representative SOFF treatment facility in the Gulong shale oil reservoirs of the Songliao Basin. Our study found that the current integrated process results in greenhouse gas (GHG) emissions of 5.63 kg CO₂-eq. Life-cycle contribution analysis identified energy demand and RO membrane as the primary environmental hotspots. These findings were further validated by sensitivity and uncertainty analyses, which underscored the critical role of grid infrastructure optimization in decarbonizing such energy-intensive treatment processes. To enhance sustainability, we proposed actionable strategies including the integration of energy recovery devices (ERD) and the extension of RO membrane lifespan. Under optimized scenarios reaching international leading standards, these measures can significantly reduce GHG emissions to 4.56 and 5.03 kg CO₂-eq, respectively. Overall, this work enhances the understanding of the environmental impacts of SOFF reclamation and provides a data-driven roadmap for the sustainable development of advanced membrane technologies in industrialized shale oil demonstration zones.