增强型地热系统垂直裂隙热储热开采过程数值模拟

摘要

增强型地热系统(Enhanced Geothermal System,EGS)作为开采深层地热资源最为有效的方法已经成为国际研究热点.充分探究EGS运行时热储内热量的开采过程对评估EGS性能及今后EGS商业开采过程中工程优化控制有着重要意义.文章建立了平行相间的垂直裂隙系统EGS开采模型,运用FLUENT软件对多平行垂直裂隙情形下增强型地热系统热储热开采过程进行了数值模拟.同时,通过改变对热储热开采过程有影响的裂隙宽度和水流速度两个参数,对比研究了其对热储热开采过程的影响.研究结果显示,裂隙宽度和水流速度对热储热开采过程影响较大,且影响效应几乎一致.当裂隙宽度为1 mm、裂隙水流速度为1 cm/s时,开采20 a时间内无论是裂隙宽度扩大1倍还是水流速度提高1倍,对热储内经济可用热能的开采率提升均超过25％,对热储内热能开采速率提升达到252％.%As the most effective method to extract deep geothermal resources,enhanced geothermal systems (EGS) has been a hot spot of academic research all over the world.It is of vital significance to make a full understanding mining process of the heat in reservoir for assessment of reservoir performance and project's optimal control.In this paper,a numerical simulation has been made to study the heat mining process in the EGS reservoir by FLUENT with vertical multi-fracture model.And the value of two influential factors,fracture width and fluid velocity has been changed to find out how they will affect the heat mining process.The results showed both the two factors have a heavy but nearly the same influence on the heat mining process.And either 1 mm of the original fracture width or 1 cm/s of fluid velocity is doubled,the mining ratio of economic & available heat energy in the reservoir has increased by over 25％,and also the mining rate of heat energy in the reservoir has increased by 252％.