| the hot dry rock geothermal energy is a r.ew clean energy and have excellent development prospects ,but is not yet exploited on large-scale in our country then to mankind : the theories and technique of the heat extraction all belong to the new task in the new field , and already have a strong appeal to the international technology worker, and already have obtain certainly achievement, on the basis of study by our predecessors, this paper do the as follows work, acquire the following main result:lx present a many fields coupling mathematics model for solid-flow-heat of 3D blocked medium in HDR. the control equation consist of completely coupled deformation equation , seepage equation , conduction and convection equation of heat, which describe the reservoir non-liner performance.2, present the detailed strategy and methods to solve this mathematics model , the basic strategy as follows:regard the deformation equation ? seepage equation conduction and convection equation of heat as separate system , and solve the equation by coupling and iterative method ;disperse the control equation in the geometry field by the finite element method(Galerkin ), and in the time field by the finite difference method: programme the computer program on this task; when the solving, take the combinative measures of the thick and thin mesh; successfully carry out the numerical simulation in vast 3D heat extraction system of HDR.3, carry out detailed numerical simulation and analysis for heat extraction of deep-seated HDR based on the Tengcongprefecture, reach the major variety rule of rock mass stress, temperature, fracture width depending on the heat extraction.(1) In the hot dry rock geotherraal energy extraction system , transportation of energy and flow of water arise mainly through the fracture, the lower temperature water attain the high temperature from the injection well to production well through conduction convection and take away the thermal from wall rock.(2) in the hot dry rock geothermal energy extraction system , the temperature of wall rock mainly trend to descend , the temperature vary on the logarithm rule (y=-29. 559Ln(x)+385. 13) nearby the production well, but on the linearity rule (y = -20.339x+573. 13) nearby the injection well.(3) In the hot dry rock geothermal energy extraction system, with the heat extraction, the temperature of the injection lower temperature water go up, but the speed descend gradually.(4) if separate the space from injection well to production well into three phase, and mark 0-200m as I , 200-500m as II , 500-700m III . the temperature will go up rapidly in I , then the speed will become even in II, and the speed is very little in III, almost towards to stability .(5) the water circulation system reach a stable state after a year when the exploitation of HDR. Namely, there a fixed stress gradient from injection well to production well keeping the normal function ,and the stress gradient is higher nearby the injection well, reaching to 43. OMPa/km, but the stress gradient is only 10. 7MPa/km in the center of the zone(6) In the hot dry rock geothermal energy extraction system , after the system start to operate, the normal stress of crack show the pronounced influence depending on the temperature's change in a month, there are a marked drop in temperature nearby the injection well, forming a lower stress area, with the heat extraction ,the temperature's change even gradually, but the temperature descend quickly nearby the production well, forming a new lower stress area.(7) In the hot dry rock geothermal energy extraction system , the fracture width widen gradually with the heat extraction , after the system start to operate, in a month the width change rapidly, the growth rate exceed 100%, and then the change become even , until 3 year, the variety is very small, almost towards to stability.(8)In the exploitation of HDR , the extraction of heat energy descend year after year with the time prolonging, and the change obey...
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