Under the “dual carbon” initiative, geothermal energy is gaining attention as a focus of development due to its stability, high quality, abundant reserves, and green, low-carbon attributes. Petroleum companies have inherent advantages in geothermal energy development, yet effective reference models and experiences for market-oriented and large-scale applications remain limited. Leveraging these advantages to advance geothermal energy development has become a new developmental challenge for petroleum enterprises. PetroChina Jidong Oilfield seized the opportunity to expand its geothermal business by utilizing a comprehensive resource assessment system, scientific planning, efficient project execution, and extensive management experience. The introduction of advanced sandstone reservoir pressure-free reinjection technology has successfully addressed the challenge of large-scale sandstone geothermal reservoir development, establishing a new model for urban district heating and clean energy substitution. This replicable and scalable “Jidong Model” provides a blueprint for traditional petroleum companies in geothermal resource development, fostering a green, low-carbon, and high-quality transformation in the industry through new productivity models.

The global energy structure is undergoing a fundamental shift from a reliance on fossil fuels with clean energy as a supplement, to a focus on clean energy supported by fossil fuels. Clean, renewable geothermal resources are gradually becoming a key energy source for sustainable development. This study focused on Gaocheng District in southwestern Hebei Province, leveraging its unique geological structural characteristics and abundant geothermal reserves. A refined geothermal resource assessment system was established, forming the basis for optimal well placement and spacing for efficient geothermal resource development. Results indicated that the development area had excellent heat source conditions, a highly favorable reservoir-caprock system, and low scaling and corrosion risks from formation fluids, indicating high-quality geothermal resources. Forty extraction and reinjection wells were deployed with a 1:1 ratio（20 extraction wells and 20 reinjection wells）. With a well spacing of 380 m and a projected operational lifespan of 30 years, the setup was expected to support sustainable heat exchange and heating needs. Based on geological structural characteristics, this study provides a valuable reference for the sustained and efficient exploitation of geothermal resources.

With the growing global demand for clean energy, geothermal resources as a renewable energy source have attracted widespread attention. This study evaluated the geothermal resource development potential and application prospects in the Xiangfu District of Kaifeng City. The results showed that the vertical temperature field of the thermal reservoir in the Xiangfu District could be divided into varying temperature zones, constant temperature zones, and increasing temperature zones, with depth significantly influencing the temperature distribution. The geothermal gradient increased with depth above 500 m and gradually decreased below 500 m. Chemical analysis of geothermal fluids showed significant differences in the water chemistry types between thermal reservoirs at different depths, with no significant hydraulic connection between the reservoirs. Based on the maximum allowable depth reduction method and the extracted water volume method, the total exploitable geothermal fluid without reinjection was estimated to be 9,390×10⁴ m³. Under complete reinjection conditions, the total exploitable geothermal fluid was estimated to be 360.7×10⁸ m³, indicating substantial development potential. These research findings provide a scientific basis and guidance for the efficient development and utilization of geothermal resources in the Xiangfu District.

Geothermal energy and petroleum are both vital subsurface energy resources. Numerical simulation of geothermal and reservoir systems is a key technology for evaluating and optimizing the development and utilization of these resources, playing an essential guiding role in the energy sector. By comparing the foundational mathematical models, numerical methods, and case studies of geothermal and reservoir simulations, this study highlights the similarities and differences in their application to the development of these two energy sources. In terms of simulation methods, geothermal numerical simulations focus on heat conduction and geothermal field variation, whereas reservoir numerical simulations emphasize fluid dynamics and the oil extraction process. Regarding simulation results, geothermal simulations are used for geothermal resource development planning and the optimization of key production parameters, while reservoir simulations are primarily applied to reserve estimation, injection-production parameter optimization, and well production management. This comparative analysis provides theoretical and practical guidance for research and applications in geothermal energy and petroleum engineering, promoting the efficient and sustainable utilization of both energy resources.

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.

Drilling medium-deep geothermal wells is costly, but converting existing depleted oil and gas wells into geothermal wells can significantly reduce these costs. This study analyzed heat extraction performance based on the engineering parameters and test data of a geothermal well reconstructed from a depleted oil and gas well in the northern Shaanxi region. Long-term heat extraction performance was simulated numerically to explore the impact of inner pipe design parameters. The study found that improving the thermal insulation of the inner pipe had a more significant impact on geothermal well heat extraction power as depth increased and flow rate decreased. However, the diameter of the inner pipe had a minimal influence on heat extraction performance and was less sensitive to changes in depth and flow rate, resulting in a limited overall impact. Additionally, the study quantified the effect of inner pipe material selection on the system's economic performance throughout its life cycle. Results indicated that reducing the inner pipe's thermal conductivity from 0.2 W/（m·K） to 0.02 W/（m·K） under certain working conditions could increase the outlet water temperature by 0.66 °C during one heating season. However, it also raised the average heating cost by 0.035 RMB/（kW·h） and extended the payback period by 1.83 a. Therefore, considering the limited benefits of using high-insulation inner pipe materials, it is recommended to prioritize temperature and pressure resistance when designing inner pipes for geothermal wells reconstructed from depleted oil and gas wells.

Geothermal energy, as a clean energy source, plays an important role in China's energy transition. Energy companies across the country are actively promoting geothermal development projects. PetroChina Jidong Oilfield Company is a leader in the large-scale development of geothermal resources and has established the largest geothermal heating demonstration base in China, the Caofeidian new town geothermal heating project. As a key project for public welfare, geothermal heating requires cost reduction, quality improvement, and efficiency enhancement for large-scale development. With long construction cycles and stringent requirements, Jidong Oilfield has achieved low-cost, high-efficiency geothermal well drilling through various technological measures, including integrated geological engineering profile design, optimization and simplification of wellbore structure, cementing design optimization, and rapid drilling technology improvements. This research combines practical case studies from the Jidong Oilfield geothermal heating project, analyzing the factors influencing cost and construction progress, identifying construction issues, and detailing countermeasures and implementation effects. This paper offers valuable solutions for optimizing geothermal well design and cost reduction in large-scale geothermal development projects.

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.