Research on drilling construction technology for CO2 geological storage in deep saline aquifers： A case study of the first CO2 geological storage project in deep saline aquifers in Shandong Province

Abstract:

The wellbore serves as the pathway for CO₂ injection into the target formation and constitutes the fundamental basis for long-term monitoring and research on both the CO₂ injected into the formation and its impact on it. Compared with conventional geothermal drilling， the wellbore of CO₂ geological storage in deep saline aquifers requires higher standards of sealing and corrosion resistance. This study takes the first CO₂ geological storage project in deep saline aquifers in Shandong Province as an example， the difficulties in drilling construction are listed， the main technical countermeasures are offered， and guidance for drilling construction of other CO₂ geological storage projects in deep saline aquifers is provided. The research results show that during the drilling construction process， the rapid drilling and corresponding mud wall protection technologies are adopted to solve the problem of poor wellbore stability. The difficulty of core sampling was solved by adding a spring clip device to prevent core from falling at the bottom of the coring tube. High-strength casing is used to solve the gas tightness and safety problems of the casing. The integrated technology of cementing， perforating and well completion using BCE-750S anti-corrosion cement is adopted to solve the problem of cement corrosion. By adding the slips packer device to the CO₂ injection pipe string， the gas tightness and stability of CO₂ injection are guaranteed. At the same time， the oil wellhead device in the oil production field is adopted， and a pressure monitoring instrument is installed to solve the long-term pressure-bearing and monitoring problems of the wellhead device.