摘要
高温地热生产井碳酸钙结垢定量评价涉及到复杂的物理和化学过程,其中井筒中的两相流研究是评价的基础.本文首先基于质量守恒、能量守恒和动量守恒方程,建立了CO_(2)-H_(2)O体系井筒两相相变稳定流动模型,提出了稳健的求解方法,并验证了其计算结果的可靠性.然后,在西藏羊八井地热田典型井开展了静止和放喷状态下的井筒中的温度和压力测试,并结合放喷试验,采用开发的模型成功评价了高温地热生产井筒两相流动过程.结果显示:气相和液相之间的速度差对井筒中温度和压力的分布有决定性的影响,不考虑气相和液体之间的速度差,会使模型计算结果远远偏离测量值.在开采速率19.10 kg/s的条件下,计算的井口温度和压力分别约为128℃和2.6 bar;井口的气相质量分数在6%~7%之间,对应的井口气相饱和度约为0.84;从闪蒸点往上大概20~30 m气相和液相中CO_(2)质量分数变化较为剧烈,也是碳酸钙结垢严重井段.
The quantitative evaluation of calcite scaling in high temperature geothermal production wells involves complex physical and chemical processes,in which the two-phase flow in the wellbore is the basis for the evaluation.Based on mass,energy and momentum conservations,this paper firstly constructs a model for governing the two-phase steady flow with phase transition in the presence of CO_(2)in the wellbore.A robust calculation method is presented and the calculation is validated.Then the temperature and pressure measurements in a typical geothermal well were carried out during discharge tests including static and dynamic test in the Yangbajing geothermal field,Tibet.Combined with the discharge test,the model is successfully used to evaluate the two-phase flow process in a high temperature production well.The results show that the velocity difference between the gas and liquid phase has a decisive impact on the profiles of temperature and pressure in the wellbore.If the velocity difference is not considered in the model,the calculations will deviate far from the measurements.At the production rate of 19.10 kg/s,the calculated wellhead temperature and pressure are about 128℃and 2.6 bar,respectively.The wellhead gas mass fraction is between 6%and 7%,and the corresponding gas phase saturation is about 0.84.The CO_(2)mass fractions in both gas and liquid phases change sharply about 20-30 m up from the flash point,indicating that serious calcite scaling will occur in this well section.
作者
雷宏武
白冰
崔银祥
谢迎春
李进
侯学文
Lei Hongwu;Bai Bing;Cui Yinxiang;Xie Yingchun;Li Jin;Hou Xuewen(State Key Laboratory of Geomechanics and Geotechnical Engineering,Institute of Rock and Soil Mechanics,Chinese Academy of Sciences,Wuhan 430071,China;CNNP Kunhua Energy Development Co.Ltd.,Hangzhou 310000,China;No.280 Research Institute of Nuclear Industry,Guanghan 618300,China)
出处
《地球科学》
EI
CAS
CSCD
北大核心
2023年第3期923-934,共12页
Earth Science
基金
国家自然科学基金项目(No.41972316)
中国核工业集团有限公司集中研发项目“地热勘查开发利用关键技术研究”
四川省科技创新人才项目(No.2022JDRC0027)。
关键词
地热能
两相流动
二氧化碳
数值模拟
羊八井
水文地质学
geothermal energy
two-phase flow
CO_(2)
numerical simulation
Yangbajing
hydrogeology
