Deep well injection and storage is an emerging technology for realizing the low-cost treatment of extremely large quantities of three types of waste in coal mines in China, while simultaneously supporting coordinated development that considers its impact on the ecological environment. There has been significant progress in research on the geological storage of carbon dioxide in China. However, the geological storage of fluids such as mine water and high-salinity water needs to be studied further. Based on a comprehensive analysis of the lithology, mineral composition, physical and mechanical characteristics, and spatial structure of the Liujiagou and Shiqianfeng formations in a mining area in the Ordos Basin, we determined the geological storage space for fluids, predicted the storage potential, and evaluated the feasibility of deep geological storage of high-salinity water in coal mines. In the study area, the Liujiagou Formation is dominated by fine sandstone and siltstone, while the Shiqianfeng Formation is dominated by medium sandstone and conglomerate. The main storage space comprises micro-cracks, as well as intergranular, dissolution, and intergranular pores. Among these, the intergranular pores are the most conducive to reservoir development. The burial depth intervals of 1820–1835 m, 1905–1920 m, and 2082–2098 m are favorable for storage and are characterized by high porosities, permeabilities, and storage capacities. The effective storage capacity within a 100 m radius of the storage well was estimated to be 33.15 × 10⁴ m³. The effective storage capacity in the favorable area is 27.69 × 10⁴ m³, accounting for 83.50% of the total storage capacity. The Liujiagou and Shiqianfeng formations thus can serve as favorable reservoirs for deep well injection and storage of high-salinity water in the Ordos Basin. This research provides new ideas for the treatment of high-salinity water in coal mines in the Ordos Basin and technical support for deep well injection and the storage of high-salinity water.

This study develops an integrated environmental–economic assessment framework to evaluate the life cycle environmental impacts and economic costs of CO₂ geological storage and produced water treatment in saline formations in China. Using a case study of a saline aquifer carbon storage project in the Ordos Basin, eight full-chain carbon capture, utilization, and storage (CCUS) scenarios were analyzed. The results indicate that environmental and cost performance are primarily influenced by technology choices across carbon capture, transport, and storage stages. The scenario employing potassium carbonate-based capture, pipeline transport, and brine reinjection after a reverse osmosis treatment (S5) achieved the most balanced outcome. Breakeven analyses under three carbon price projection models revealed that carbon price trajectories critically affect project viability, with a steadily rising carbon price enabling earlier profitability. By decoupling CCUS from power systems and focusing on unit CO₂ removal, this study provides a transparent and transferable framework to support cross-sectoral deployment. The findings offer valuable insights for policymakers aiming to design effective CCUS support mechanisms under future carbon neutrality targets.

Deep well injection and storage (DWIS) technology provides an effective alternative to address the high cost, energy intensity, and limited scalability of conventional treatments for high-salinity mine water from coal mines. However, the absence of a dedicated site suitability evaluation framework remains a major gap. Unlike previous approaches that directly applied CO₂ storage criteria, this study refines and restructures the framework based on a systematic analysis of the fundamental differences in mechanisms and risk characteristics unique to mine water storage. Building on the experience of CO₂ geological storage assessment, this study analyzes the key differences in fluid properties and storage mechanisms between water and CO₂ and, for the first time, establishes a comprehensive site suitability evaluation framework for mine water geological storage. The framework integrates three main dimensions—stability and safety, effectiveness, and socio-economic factors—covering 80 key parameters. The indicator system is organized hierarchically at the basin, target-area, and site levels, and incorporates a multi-scale weight adaptation mechanism that assigns scale-dependent weights to the most influential indicators at each evaluation level. An innovative evaluation methodology combining a “one-vote veto” mechanism, progressive filtering, and multi-factor weighted superposition is proposed to determine storage suitability. This work fills a critical research gap in systematic site selection for deep mine water storage in China. It offers theoretical guidance and an engineering paradigm for overcoming technological bottlenecks in high-salinity water treatment, enabling efficient and low-carbon disposal. The study has important implications for promoting the green transformation of the mining industry and achieving national carbon peaking and neutrality goals.