增强型地热系统不同注采井网参数分析

Parametric Analysis of Different Injection and Production Well Pattern in Enhanced Geothermal System

针对增强型地热系统中水通过复杂裂缝系统提取干热岩储层热量的过程,基于离散裂缝网络模型热流耦合构建了增强型地热系统的解析模型,利用Laplace变换得到了干热岩储层解析解,分析了在五点井网开采下注采井网参数对出口端温度及热提取的影响。研究结果表明:不同裂缝网络和井网模型下出口端温度下降幅度和热突破的时间不同;在相同裂缝网络下,井距越大,热突破时间越晚,当井距分别为50.0、100.0和150.0m时,热突破时间分别为2.0、5.2和15.0a;注水速率越小,温度下降越慢,当注水速率分别为0.1,0.2和0.3kg/s时,生产20.0a,温度下降幅度分别为53.0,34.5和26.8℃;通过正交实验分析方法得到注采参数中井距影响最大,其极差为13.15,其次为注水速率和注水温度,井网模型影响最小。

According to the process of heat extraction of fracture system in enhanced geothermal system(EGS)dry-hot-rock reservoir,a thermal-hydraulic coupling analytical model was established based on the discrete fracture network model.The Laplace transform was used to obtain the analytical solutions.The influence of the parameters of injection and production of five spot pattern was analyzed for the temperature and heat extraction at outlet.The results show that the temperature drop at outlet and the time of thermal breakthrough are different under different fracture network and well types.Under the same fracture network,the larger the fracture spacing is,the later the thermal breakthrough time is.When the fracture spacing is 50.0,100.0 and 150.0 m,the thermal breakthrough time is 2.0 a,5.2 aand 15.0 a,respectively.The smaller the injection rate is,the slower the temperature decreases.When the injection rate is 0.1,0.2 and 0.3 kg/s,in production of 20.0 a,the temperature decreases by53.0,34.5,and 26.8℃,respectively;Orthogonal experimental analysis shows that well spacing has the greatest influence on injection-production parameters with a range of 13.15,followed by injection rate and injection temperature,while well type has smallest influence.