城市深层地热能可持续开采多场耦合效应数值模拟研究进展

Coupled multi-field effect on sustainable development of deep geothermalenergy in cities

我国中深层(200~3000 m)和深层(>3000 m)地热资源储量丰富,具有很大的开发空间,可持续开发利用地热资源将是碳达峰、碳中和目标如期实现的重要保障之一。然而,地热能开采过程涉及复杂的温度场、渗流场、应力场耦合效应。为此,总结了笔者团队在水热型地热资源开发利用多场耦合效应数值模拟方面的研究成果,包括面向城市深层地热能可持续开采的资源量评价、采灌方案优化设计方法和在典型地热工程中的示范应用。从温度、水位、变形3个方面给出了深层地热能可持续开采的多指标评价体系,以及基于数值模型的可采地热能计算公式。基于深层地热井-储系统多场耦合数值模型给出了满足可持续开采标准的可采地热能评价方法,提出了开采井风险评价的“红绿灯系统”,并依托雄安新区容东安置区地热开发利用工程验证了资源评价方法的合理性。基于深层地热井-储系统多场耦合数值模型给出了满足可持续开采标准的采灌方案优化设计方法,采用Plackett-Burman设计构建了代理模型,通过多响应优化实现了参数的快速优化,并依托北京市城市副中心地热开发利用工程验证了采灌方案优化设计方法的合理性。为城市深层地热能可持续开采提供了理论与工具支撑,以促进城市深层地热能更大规模和更高质量的开发利用。

There is abundant geothermal resource in the intermediate-deep(200-3000 m)and deep(>3000 m)geothermal reservoirs in China,which has great potential for development,and the sustainable development and utilization of geothermal energy is one of the important guarantees for carbon peaking and carbon neutrality goals to be achieved on schedule.However,the exploitation process of geothermal energy involves some complex interactions between temperature,seepage and stress fields.Therefore,the achievements on the coupled multi-field effects in the development of hydrothermal geothermal resources obtained by the authors are summarized,including the resource assessment for the sustainable development of urban deep geothermal energy,the method of optimal design of exploitation schemes,and demonstrated applications in typical geothermal engineering.A multi-index assessment system for the sustainable development of urban deep geothermal energy from the aspects of temperature,water level and deformation,as well as the calculation formula of recoverable geothermal energy based on numerical model are proposed.Based on the coupled multi-field numerical model of deep geothermal well-reservoir system,the method of recoverable geothermal energy assessment which meets sustainable development criteria is presented,and the‘traffic light system’for the risk assessment of production wells is proposed.Relying on the urban geothermal development project in the Rongdong resettlement district of Xiongan New Area,the rationality of the proposed method of geothermal energy assessment is demonstrated.Based on the coupled multi-field numerical model of deep geothermal well-reservoir system,the method of optimal design of exploitation schemes which meets the sustainable development criteria is presented,the surrogate model is constructed by the Plackett-Burman design,and the rapid optimization of parameters is realized by multiple response optimization.Relying on the urban geothermal development project in the Beijing Municipal Administrative Center,the rationality of the proposed method of optimal design of exploitation schemes is demonstrated.In this study,the theoretical and numerical supports for the sustainable development of urban deep geothermal energy are provided,which promotes the development and utilization of urban deep geothermal energy on a larger scale and with higher quality.