Numerical Simulation On Exploiting Geothermal Energy From An Abandoned Five-Spot Well Pattern

Exploiting geothermal energy from abandoned wells is one of the current international research hotspots.The domestic research in this field is still in the preliminary exploration stage.Through the systematic investigation of geothermal energy development technology and numerical simulation research status of abandoned wells at home and abroad,it is found that the existing development process can be divided into two types: open loop heat extraction process(EGS,“irrigation-pumping” heat extraction)and closed loop heat extraction process(heat exchanger heat extraction,“U-shaped well”heat extraction).At present,the main object of numerical simulation research on heat extraction from abandoned wells is closed-loop heat extraction process.However,the research on numerical simulation of exploiting geothermal energy from abandoned well pattern needs to be supplemented and expanded.Aim at this problem,the paper proposes a new production method of exploiting geothermal energy from abandoned five-point well pattern.Based on the “U-shaped well” heat extraction,we proposed to transform the abandoned five-point well pattern into a closed-loop geothermal system.A transient heat transfer model is established to study the influence of key parameters such as flow rate,inlet temperature and well pattern deployment on the heat recovery performance of the system,and the accuracy of the model is verified by field data.It is pointed out that the secondary drilling is required to convert the abandoned fivepoint well pattern into a closed-loop geothermal system will increase the costs and reduce the feasibility of field construction.We proposed to convert the abandoned five-point well pattern into an open-loop geothermal system which has a stronger reconstruction feasibility,and the influence of different production parameters on the thermal recovery performance of the open-loop geothermal system is studied by numerical simulation.After comparing the advantages and disadvantages of the two systems and the thermal recovery performance,it is found that the open-loop geothermal system has stronger thermal recovery performance,and is more suitable for the geothermal energy development of abandoned five-point well pattern in actual production.In this paper,two production forms of exploiting geothermal energy from abandoned five-point well pattern are proposed.Numerical simulation was carried out to study the influence of key production parameters on the thermal recovery performance of the system.It can provide reference for subsequent domestic research.