In the heart of Shandong, China, researchers are delving into the fiery depths of geothermal energy, seeking to unlock the secrets of heat-damaged granite. Their findings could revolutionize the way we harness energy from the Earth’s crust, offering a glimpse into a future where geothermal power becomes a more viable and efficient source of clean energy.
Dr. Wu Xinghui, from the School of City and Architecture Engineering at Zaozhuang University, is at the forefront of this research. His team has been exploring the behavior of deep granite rocks under extreme heat conditions, mimicking the environment found in dry-hot granite reservoirs. “Understanding how these rocks react to thermal stress is crucial for the efficient extraction of geothermal energy,” Dr. Wu explains. “The mechanical properties of the rocks change significantly when exposed to high temperatures, and this affects how we can safely and effectively extract energy from them.”
The team subjected granite samples from Yantai, Shandong, to thermal shock treatments, simulating the conditions found in deep geothermal reservoirs. They then used the Brazilian splitting test, a method that involves applying a compressive force along the diameter of a disk-shaped sample, to observe how the rocks fracture. By combining this with digital image processing technology, they could monitor the initiation, propagation, and penetration of fractures on the rock’s surface in real-time.
Their findings, published in the Journal of Mining Science, reveal that the thermal damage process alters the rock’s microstructure, leading to two distinct crack initiation patterns during the splitting process. As the temperature increases, the longitudinal wave velocity and indirect tensile strength of the rock decrease. This is a critical finding for the energy sector, as it provides insight into the temperature thresholds at which the rock’s mechanical properties change most significantly.
Within the range of 450 to 600 degrees Celsius, the team observed a linear relationship between the temperature and the decrease in the rock’s longitudinal wave velocity and indirect tensile strength. This temperature range is particularly relevant for geothermal energy extraction, as it is within the range of many dry-hot granite reservoirs.
The implications of this research are far-reaching. By understanding how heat affects the mechanical properties of granite, energy companies can develop more efficient drilling and extraction methods. This could lead to a significant increase in the amount of geothermal energy that can be extracted from a single reservoir, making geothermal power a more competitive and viable source of clean energy.
Moreover, this research could pave the way for the co-extraction of deep geothermal resources and minerals. As Dr. Wu puts it, “The future of geothermal energy lies in our ability to extract not just heat, but also the valuable minerals found in these deep reservoirs. This research brings us one step closer to that future.”
As the world continues to seek out clean and renewable energy sources, the work of Dr. Wu and his team offers a promising path forward. Their research, published in the Journal of Mining Science (translated from 矿业科学学报), provides valuable insights into the behavior of heat-damaged granite, paving the way for more efficient and effective geothermal energy extraction. The future of geothermal energy is heating up, and it’s all thanks to the work of dedicated researchers like Dr. Wu.