地热能作为一种关键的清洁可再生资源，在中国储量丰富，尤其是中深层地热，资源开发潜力巨大。推动中深层地热资源的开发利用，对于优化中国能源消费结构、实现节能减排以及推进“双碳”目标具有深远影响。研究以陕西地区某地热井为例，提出了在地热井同-井筒内实施“下采上灌”的技术方案，综合考虑了内管-环空-井周地层的动态换热过程，构建了水平井井筒和储层流固热三维耦合模型，通过这一模型深入探讨了隔层厚度、地层渗透率和孔隙度以及完井管柱结构对取热效果的影响。研究结果表明隔层的有无对取热效果的影响显著。无隔层时，在分层采灌30 a后，采出水温度下降高达9 ℃。隔层厚度为40 m时，取热效果最好。在开采量和回灌量一定时，回灌层和隔层的孔隙度和渗透率的降低会降低取热效果，而开采层的渗透率和孔隙度对取热效果的影响不显著。

Geothermal energy, as a key clean and renewable resource, is abundant in China, particularly in medium- to deep-layer geothermal reservoirs, which hold significant development potential. Promoting the development and utilization of medium- to deep-layer geothermal resources is crucial for optimizing China’s energy consumption structure, achieving energy savings and emissions reductions, and advancing the “Dual Carbon” goals. This study took a geothermal well in Shaanxi as an example and proposed a “lower production and upper reinjection” technical scheme implemented within a single wellbore. By comprehensively considering the dynamic heat exchange processes among the inner pipe, annulus, and surrounding formation, a 3D coupled thermal-fluid-solid model of the horizontal wellbore and reservoir was established. The model was used to investigate the effects of interlayer thickness, formation permeability and porosity, and completion tubing structure on heat extraction efficiency. Results indicated that the interlayer significantly impacted heat extraction. Without an interlayer, the extracted water temperature decreased by as much as 9°C after 30 a of stratified production and reinjection. The optimal heat extraction was achieved with an interlayer thickness of 40 m. While maintaining constant production and reinjection rates, reductions in porosity and permeability of the reinjection layer and interlayer negatively impacted heat extraction, whereas the permeability and porosity of the production layer had minimal influence.