Evaluation Of Hydrothermal Sandstone Geothermal Development Effect And Analysis Of Formation Deformation Effect

China's hydro-thermal geothermal resources are very rich,the development potential is huge,but mainly concentrated in shallow mining,deep geothermal due to mining efficiency constraints and not large-scale development,at the same time,deep geothermal mining in the formation of deformation caused by the environmental problems can not be ignored.Based on the investigation of Geothermal reservoir characteristics and mining mechanism,combined with the theory of seepage mechanics of thermodynamic porous media,Darcy's law,mass conservation equation and energy conservation equation,this paper establishes the mathematical model of heat flow solid coupling in geothermal mining,and gives the analytic solution of one-dimensional settlement calculation in geothermal mining.The process of typical deep strati-graphic mining is numerically analyzed by adaptive implicit method,and the results of three parameters distribution in this complex process are given,combined with the actual working conditions of geothermal mining and the dielectric characteristics of geothermal reservoirs,the early stage of geothermal mining,The parameter sensitivity analysis of thermal energy development effect and formation deformation and its main influencing factors in the operation period and mining process is carried out respectively,which provides a theoretical basis for the rational arrangement of geothermal energy Mining scheme and the control of formation deformation.The main research results are as follows:(1)Based on the analysis of the geological conditions of hydro-thermal geothermal resources,combined with the reservoir characteristics of pore-type thermal reservoirs,the mathematical model of geothermal mining of hydro-thermal sandstone is established.The tectonic region of Xi'an sag in Guanzhong Basin was selected as the research area,and the numerical simulation experiment was designed by Box-Behnken test method,and the sensitivity mechanism of each factor to heat extraction performance(heat extraction temperature and heat extraction power)and formation deformation was obtained by the influence analysis of response surface.(2)In the early stage of geothermal mining,the initial temperature in the physical parameters has the greatest influence on the heat extraction performance,the initial temperature from 100? and 150? geothermal field,mining after 30 years of heat extraction temperature,the latter i5 41%higher than the former,the heat extraction power is 59%,and the change of permeability and thermal conductivity has no obvious effect on the heat extraction performance,but it has an effect on the bottom hole pressure and heat transfer process respectively.(3)In the operation period of geothermal mining,the well spacing in the working system parameters has the most significant effect on the heat extraction performance in the 100?175m range,and the increase of the well spacing after 175m has no effect on the heat extraction performance,which is unfavorable to the heat extraction temperature during the increase of well flow rate,but can improve the thermal power.Under the condition of fixed flow mining,the perfection degree of well has a significant effect on the heat extraction performance,and when the perfection degree rises from 33%to 100%,the temperature of the production well can be increased by 13.5%,the thermal power is increased by 45.5%,and the ejection degree and well diameter have great influence on the bottom hole pressure.(4)In the study of the formation deformation effect caused by geothermal mining,it is found that the formation deformation mainly occurs in the early stage of mining(in the first 1-2 years),and the size of the influence of the parameters discussed on the formation deformation is ranked as:initial temperature>Well perfection>Well flow>well spacing.The main reasons affecting the differential deformation of each experimental scheme are the different changes of temperature field,in which the effect of well spacing on the deformation of the injection well is small,and the effect on the deformation of the production well is remarkable.