St1 Deep Heat Project with its two deep wells extending to 6.2 - 6.4 km depth is the world’s deepest industrial geothermal energy project. The aim is to build an EGS (enhanced geothermal system) at the depth of about 5 - 6 km. The project is a pilot aiming at exploring the technical and economic feasibility of geothermal energy in the crystalline rock conditions of Finland for production of thermal power to a district heating network. Due to the demands of the district heating, the aim is to produce hot fluid at about 100C and re-inject it to the formation at 50C. The 100C goal requires to drill to about 6 km depth. The drill site is located in Espoo, next to the Fortum district heating plant on the Aalto University campus. So far (2020) the project has drilled a 2 km deep completely cored pilot hole (OTN-1), and two deep wells OTN-2 to 6.2 km and OTN-3 to 6.4 km. Hydraulic conductivity has been enhanced by hydraulic stimulation in both deep wells in 2018 and 2020. The extreme depth level sets significant challenges for drilling and hydraulic stimulation, as well as controlling of induced seismicity. At present, the project proceeds with the installation of production pumps in OTN-2 and OTN-3, and first test cross-hole pumpings are expected to start in January 2021. In the presentation we provide an insight to the project and its major achievements and challenges.

St1 Deep Heat Project 的两口深井延伸至 6.2 - 6.4 公里深度，是世界上最深的工业地热能源项目。目的是在大约 5 - 6 公里的深度建立一个 EGS（增强型地热系统）。该项目是一个试点项目，旨在探索在芬兰结晶岩条件下利用地热能为区域供热网络生产热电的技术和经济可行性。由于区域供热的需求，目标是生产约 100 摄氏度的热流体并在 50 摄氏度时将其重新注入地层。100C 目标需要钻到大约 6 公里的深度。钻探地点位于埃斯波，毗邻阿尔托大学校园的 Fortum 区域供热厂。到目前为止（2020 年），该项目已钻探了 2 公里深的完全取芯导向孔（OTN-1）和两口深井 OTN-2 至 6。2 公里和 OTN-3 到 6.4 公里。2018 年和 2020 年，两口深井的水力增产提高了导水率。极端深度水平对钻井和水力增产以及诱发地震活动的控制提出了重大挑战。目前，该项目在 OTN-2 和 OTN-3 安装生产泵，预计 2021 年 1 月开始首次测试跨孔泵送。在演示中，我们提供了对该项目及其主要成就的见解和挑战。