CO_(2)单井增强地热系统取热性能研究  

Heat Extraction Performance of CO_(2) Single-Well Enhanced Geothermal System

作　　者：卜宪标 郭志鹏[1,2] 李华山 王显龙[2] 龚宇烈[2] 王令宝[2] BU Xian-biao;GUO Zhi-peng;LI Hua-shan;WANG Xian-long;GONG Yu-lie;WANG Ling-bao(School of Engineering Science,University of Science and Technology of China,Hefei 230026,China;Guangzhou Institute of Energy Conversion,Chinese Academy of Sciences,Guangzhou 510640,China)

机构地区：[1]中国科学技术大学工程科学学院,合肥230026 [2]中国科学院广州能源研究所,广州510640

出　　处：《新能源进展》2022年第6期509-518,共10页Advances in New and Renewable Energy

基　　金：国家自然科学基金项目(42102336)。

摘　　要：为提高闭式单井系统取热性能,提出一种CO_(2)单井增强地热系统(CO_(2)-SEGS)。建立井筒流动换热和储层热−流−固耦合的数学模型,考虑CO_(2)可压缩性以及井纵向压力传递特性,对比分析了水和CO_(2)在SEGS中的取热性能,研究系统取热性能与封隔间距、井筒保温的关系。结果表明:(1)额定循环流量下,井口生产温度从134.09℃降低至116.06℃;CO_(2)在采出过程中降压膨胀做功,产生明显的温降效应,中心管井口温度比底部低约57℃。(2)井筒不同位置处CO_(2)的密度、热容差异很大,当循环流量小于50 kg/s时,依靠浮升力作用,SEGS可实现自主循环运行,无需额外泵功。(3)当水和CO_(2)的流量分别为15 kg/s和40 kg/s时,两者年均取热速率近似相等,CO_(2)的采出温度比水低约40℃,而压力损耗远小于水。(4)SEGS取热性能与封隔间距以及中心管保温性能呈正相关。研究结果可为SEGS系统的开发提供参考。A CO_(2) single-well enhanced geothermal system(CO_(2)-SEGS)was proposed to improve the heat transfer capacity.A mathematical model of a coupling of the wellbore and reservoir was developed,and CO_(2) compressibility and longitudinal pressure transfer were considered.The heat extraction performance of water and CO_(2) in SEGS was compared and analyzed to study the relationship between heat extraction performance and sealing spacing and well tube insulation.The following research results were obtained.First,the wellhead production temperature decreased from 134.09oC to 116.06oC under the rated injection flow,and CO_(2) expanded to do work with the drop of its pressure in the extraction process so as to generate a remarkable temperature drop effect with a temperature drop of about 57oC.Second,the density and heat capacity of CO_(2) varied greatly at different locations of the well tube.When the injection flow was less than 50 kg/s,SEGS can achieve independent circulation through buoyancy without additional pump power.Third,when the flow rates of water and CO_(2) were 15 kg/s and 40 kg/s,respectively,their average output power was approximately equal,the production temperature of CO_(2) was about 40oC lower than that of water,while the pressure loss was much less than that of water.Fourth,SEGS heat extraction performance was positively correlated with the sealing spacing and the insulation performance of the central pipe.The results can be used to guide the development of SEGS.

关 键 词：地热能 单井 数值模拟 增强型地热系统 超临界CO_(2) 

分 类 号：TK529[动力工程及工程热物理—热能工程]