The Development Laws and Parameters of Geothermal Extraction from Different Abandoned Well Types in Oil Fields

To address the potential geological hazards and environmental pollution associated with traditional direct utilization methods of geothermal water, a new geothermal development approach, emphasizing "taking heat without water" and utilizing a coaxial casing heat exchange system as the core component, is proposed. Numerical models of the coaxial casing closed-loop heat transfer system are established for both straight wells and multi-branch wells, comparing heat extraction efficiency and conducting a sensitivity analysis of the parameters involved. The results demonstrate that the multi-branch well system achieves higher outlet temperatures and heat extraction power than the straight well system under identical conditions; however, this also leads to a significant increase in injection pressure. The different well types show similar responses to varying parameters, with differences primarily in degree. Factors that significantly influence the system's heat extraction efficiency include the injection temperature, flow rate, length of the insulation pipe, and thermal conductivity of the formation and cement. The study provides valuable guidance on selecting well types for deep geothermal extraction.