利用废弃油井和高温溶腔开采地热能的数值模拟

NUMERICAL SIMULATION OF EXPLOITING GEOTHERMAL ENERGY USING ABANDONED OIL WELL AND HOT CAVITY

探究以废弃油井作为注入井和采出井,以高温溶腔作为主要热储的换热系统,建立注入井和采出井的二维换热模型,利用有限差分法离散其能量的偏微分方程,并用交替半隐式算法(ADI)求解温度场;建立高温溶洞换热的三维换热模型,考虑其多孔性质,并利用有限元分析软件Fluent进行数值分析。该文中工质的物性来源于美国国家标准与技术研究院(NIST)数据库提供的实际气体模型,分析过程中考虑其物性变化,探究流体出口温度随运行时间、地温梯度、入口压力、入口温度、质量流量、岩层孔隙率、工质种类等因素的变化规律,研究结果表明,影响工质出口温度最重要的因素为入口温度、地温梯度和质量流量,在实际开采过程中应重点考虑这几个因素。

A heat transfer system using abandoned oil well as its injection and production well and hot cavity as its geothermal reservoir was studied. The 2D heat transfer model of injection and production well was established, and its energy partial differential equation was discretized by finite difference method and the temperature field was solved through alternating semi-implicit algorithm. The 3D heat transfer model of hot cavity was set up by considering its porous property, and numerical analysis was developed using finite element analysis software Fluent. The property of working fluid used real gas model from the database provided by NIST. The various property of fluid was taken into account in the whole analysis, and the change of fluid temperature of the system＇ s outlet following changing of running time, geothermal gradient, pressure and temperature at inlet, mass flow rate, rock＇ s porosity and different working fluid was studied. The results indicate that inlet temperature, geothermal gradient and mass flow rate are the most important factors affecting outlet temperature, so these factors have to be considered in the actual process of exploitation.