Research and exploration on Shaanxi Coal Group’s 4 million t/a CO₂ capture and storage technology

While modern coal chemical industry addresses national energy security demands, its exploration of green development pathways featuring source emission reduction and terminal decarbonization holds significant implications for global climate change mitigation, environmental protection, sustainable development promotion, and carbon neutrality achievement. Shaanxi Coal and Chemical Industry Group plans to construct a 4 million t/a CO₂ capture and storage (CCS) project, which will drive its own green and low-carbon development, and contribute to the nation’s accelerated realization of carbon peak and carbon neutrality goals. From the perspectives of CO₂ capture, compression, transportation, storage environment, and monitoring, the feasibility and reliability of implementing large-scale CO₂ geological storage in the East margin blocks of Ordos Basin were investigated through process optimization, scheme optimization, numerical simulation, and other methods. Specifically, the results show that: the process flow is designed based on the “vacuum desorption + air cooling” technology to capture high-purity CO₂ (99.9% concentration, annual capture capacity of 3.87 million tons, with a nominal processing capacity of 4 million t/a) from the low-temperature methanol wash unit of coal chemical facilities. The captured CO₂ is then compressed to supercritical state through four sets of CO₂ compressor units and transported to the storage site. Drawing on oil/gas reservoir development well patterns such as square configuration and five-spot flooding, the proposal adopts a dual-row well array layout to meet the annual CO₂ storage capacity requirement of 4 million t/a with booster stations added at injection wellheads. Through series connection of wellheads, this achieves 2 million t/a CO₂ injection capacity per row. Based on core analysis from Well Yutan-1 and CO₂ injection practical achievements at Well Shenzhu-1, five reservoir-caprock combinations from Yanchang Formation to Majiaogou Formation ( > 1 000 m depth) are selected as large-scale CO₂ storage targets. By numerical simulation, comparing multiple storage area schemes and considering single-well injectivity in Type-I favorable reservoir-capacity zones (saline aquifers), the study concludes that mobilizing 400 km² formation area and constructing 30 injection wells could meet future 80-million-ton CO₂ storage demand, with proposed wellhead injection pressure parameters. Considering the safety cycle of CO₂ permanent geological storage, the early, middle and late CO₂ storage monitoring ideas were constructed, and four monitoring mechanism suggestions and monitoring well planning were deployed to form a whole process monitoring system for 4 million t/a CO₂ safe storage, providing reference for large-scale CO₂ geological storage at home and abroad.