Key technologies for exploitation and utilization of geothermal fields in fluvial sandstone thermal reservoirs: A case study of Gaoshangpu-Liuzan geothermal field in Nanpu Sag, Bohai Bay Basin

The Nanpu Sag in the Huanghua Depression of the Bohai Bay Basin is rich in geothermal resources, with multiple geothermal fields identified, including Gaoshangpu-Liuzan, Nanpu, and Matouying. The thermal reservoirs, primarily composed of fluvial sandstone from the Guantao Formation, exhibit advantages such as high temperatures（70-90 ℃）, significant water amounts (100 m3/h), large-scale reservoirs, and thick caprocks. However, their development faces several challenges, including optimal target area selection, sustainability evaluation, efficient drilling and production processes, reinjection into sandstone reservoirs, long-distance centralized thermal water transportation, and intelligent monitoring. To address these challenges, practical exploration in the Gaoshangpu-Liuzan geothermal field has led to the development of five core technologies: 1） optimization and detailed resource evaluation technology for exploration areas; 2） well placement and thermal field simulation technology; 3） geothermal well drilling, completion, and pressure-free reinjection for sandstone thermal reservoirs; 4） multi-well collection and long-distance thermal water transportation technology; 5） intelligent management and control technology for geothermal development. These advancements provide technical support for geothermal heating projects in the Gaoshangpu-Liuzan geothermal field and the geothermal development efforts of Jidong Oilfield.