Numerical Simulation Of Carbonate Fracture Reservoir Coupled Thermal-Hydraulic In North China Buried-Hills During Heat Extraction Process

Geothermal resources are characterized by abundant reserves,wide distribution,renewable,stable and continuous.The direct utilization of geothermal energy in China works well which has ranked first worldwide.North China is relatively rich in geothermal resources,and the development and utilization are mainly for heating.With the increase of heating demand,the mining efforts are gradually increasing in recent years.Carbonate thermal reserves are the major geothermal resources for development,it’s large-scale development has become the key direction of geothermal resources exploration.The development of deeper geothermal formation is of great significance to the improvement of heating capacity.The research area is located in the Rongcheng geothermal of Xiong’an New Area,North China.The Gaoyuzhuang Formation of the deep Jixian System fracture thermal reservoir is taken as the research object.Fracture geometry networks are the key to influence the thermal transfer behavior of reservoir seepage.Thermal-hydraulic coupling analysis is an indispensable process to evaluate thermal storage capacity and mining life.In this paper,COMSOL Multiphysics is used as a multi field coupling numerical simulation platform to study the seepage and heat transfer of geothermal reservoirs.On the basic of equivalent medium model,dual medium model and discreted fracture network,the geothermal reservoir model with multi-field coupling is established and the spatial-temporal evolution and mechanism of seepage heat transfer in thermal reservoir in 30 years are analyzed.The analysis of injection flow,injection temperature and open hole parameters is carried out to derive the reasonable parameters for the operation of the thermal system under current geological conditions.In order to improve the well production,hydraulic fracturing were conducted,and the productivity was obviously improved.By comparing the breakthrough period of different mining time schemes after hydraulic fracturing,10kg/s,303K scheme used for five mouths per year and the thermal energy of a single well were 3.14×10¹⁵J,which equivalent 10.71 ten thousand tons of standard coal.It’s provide a foundation for sustainable development and utilization of geothermal reservoirs.