Geological storage conditions and potential assessment of CO₂ in deep saline aquifers in Lindian of Heilongjiang Province

Geological storage of CO₂ is an effective measure to reduce carbon emission and mitigate greenhouse effect. Through geothermal exploration and comprehensive research, it is found that the sandstone stratified strata of the Third and Fourth Member of the Quantou Formation, the Qingshankou Formation and the Yaojia Formation of the Cretaceous age in the Lindian area of Heilongjiang Province, with the burial depth of about 940−2062 m, contain rich saline water with TDS of 2000−9000 mg/L, and are of well-developed pores and slow groundwater flow. The caprock is dominated by pelite stratified strata of the Nenjiang Formation, Sifangtai Formation and Mingshui Formation of the Cretaceous age, with a thickness of about 800−1300 m. It has not been penetrated by major fault zones and is well closed, which determines that it can be used as a good geological reservoir for CO₂ storage. At the same time, Lindian is close to the city of Daqing, with numerous chemical enterprises, concentrated and sufficient carbon sources, and large scale and short distance, providing favorable conditions for CO₂ geological storage in the study area. Due to the lack of oil and gas resources and oil wells in the Lindian area, this work uses geothermal exploration wells for the first time. According to the mechanism of CO₂ geological storage technology and the international authoritative potential assessment formula, the potential assessment of CO₂ geological storage of deep saline aquifers in this area is carried out. The results show that the theoretical CO₂ storage in the deep salt aquifers is 478.91×10⁸ t, the effective CO₂ storage is 11.49×10⁸ t, which is of large storage potential. In the future, it can provide geological storage sites for carbon reduction in Daqing, Qiqihar and other neighboring cities. The implementation of this work provides technical support for the next implementation of CO₂ geological storage suitability evaluation, objective target area and site selection and demonstration projects in the Lindian area.