In the heart of China’s Xiong’an New Area, a groundbreaking study led by Ya-hui Yao from the Center for Hydrogeology and Environmental Geology, China Geological Survey, has shed new light on the vertical distribution of heat flow in the Niutuozhen geothermal field. The findings, published in the Journal of Groundwater Science and Engineering, could significantly impact the geothermal energy sector by providing a deeper understanding of heat flow dynamics in ancient geothermal systems.
The study focused on the D01 deep geothermal scientific drilling well, which exposed the entire Gaoyuzhuang Formation karst geothermal reservoir and drilled 1,723.67 meters into the Archean crystalline basement. This depth provided a unique opportunity to analyze the vertical distribution of heat flow, a critical factor in understanding and harnessing geothermal energy.
The research revealed distinct segmentation in the geothermal gradient and rock thermophysical properties. The Gaoyuzhuang Formation, dominated by convection, showed significant temperature inversions corresponding to karst fracture developments. In contrast, the Archean crystalline basement exhibited conductive heat transfer. After 551 days of static equilibrium, the average geothermal gradients were determined to be −0.8°C/km for the Gaoyuzhuang Formation and 18.2°C/km for the Archean crystalline basement.
Ya-hui Yao emphasized the significance of these findings, stating, “The heat flow of the Neogene sedimentary caprock is significantly higher than that of the Archean crystalline basement at the D01 well, with an excess of 44.7 mW/m2 accounting for approximately 50% of the total heat flow in the Neogene sedimentary caprock.” This discrepancy is primarily attributed to lateral and vertical thermal convection within the high-porosity and high-permeability karst dolomite layer and the Niudong fault, respectively.
The study calculated the Archean heat flow at the D01 well as (43.9±7.0) mW/m2, while the heat flow for the Neogene sedimentary cap was estimated at 88.6 mW/m2. This quantitative revelation of the vertical distribution of heat flow provides empirical evidence for the genetic mechanism of the convection-conduction geothermal system in sedimentary basins.
The implications of this research are vast for the energy sector. Understanding the vertical distribution of heat flow and the mechanisms behind it can help optimize geothermal energy extraction. By identifying the areas with the highest heat flow, energy companies can target these zones for more efficient and cost-effective geothermal power generation. This could lead to a significant boost in the viability of geothermal energy as a renewable and sustainable power source.
Moreover, the study’s findings could influence future geothermal projects by providing a clearer picture of the subsurface heat dynamics. This knowledge can guide drilling strategies, reservoir management, and the overall design of geothermal systems, potentially reducing risks and enhancing the economic feasibility of geothermal projects.
As the world continues to seek sustainable energy solutions, the insights from Yao’s research offer a promising pathway forward. By leveraging the unique characteristics of ancient geothermal systems, the geothermal energy sector can unlock new potential and contribute to a greener energy future.