In the quest to mitigate climate change and transition to sustainable energy sources, researchers are exploring innovative strategies that combine carbon dioxide (CO2) sequestration with geothermal energy extraction. A recent study published in *Meitian dizhi yu kantan* (which translates to *Geotectonics and Metallogeny*) offers a promising approach that could revolutionize how we manage deep saline aquifers, enhancing both CO2 storage and geothermal energy production.
Led by Zehao Xie from the State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation at Southwest Petroleum University in Chengdu, China, the research proposes a novel method that integrates CO2 sequestration with geothermal energy extraction in deep saline aquifers. These aquifers, characterized by high geothermal gradients and abundant geothermal resources, present an ideal environment for such dual-purpose development.
The study employs a thermo-hydro-chemical coupling numerical simulation model to explore the optimal injection mode, well patterns, and injection and production parameters. The findings reveal that extracting formation water and geothermal energy during CO2 injection can significantly delay the rise in formation pressure, thereby increasing the CO2 storage capacity by 16,500 tons. “This approach not only enhances the storage capacity but also provides a sustainable method for geothermal energy extraction,” Xie explains.
After the depletion of movable water, the study found that further geothermal energy extraction using CO2 as the work fluid yielded an additional 6.60 MJ of heat and increased the CO2 storage capacity by 30,800 tons. Geochemical reactions during CO2 injection also improved reservoir porosity and permeability, creating favorable conditions for continuous CO2 injection and geothermal energy extraction.
The research identifies intermittent injection as the optimal injection mode, as it delays the rise in formation pressure to the greatest extent. It also recommends arranging production and injection wells in the same aquifer, with more injection wells in the structurally lower parts of reservoirs compared to production wells. The optimal injection and production parameters include an injection rate of 10,000 cubic meters per day, an injection-to-production rate ratio of 0.8, an injection cycle of three months, and a cyclic injection-to-production time ratio of 1.
This innovative approach offers a novel philosophy for geologic CO2 sequestration in deep saline aquifers and serves as a valuable reference for achieving carbon neutrality and peak carbon dioxide emissions goals. By promoting efficient, collaborative resource development, this method could significantly impact the energy sector, providing a sustainable solution for both CO2 storage and geothermal energy production.
As the world seeks to transition to cleaner energy sources, research like this highlights the potential for integrating multiple technologies to achieve sustainable development goals. The findings published in *Meitian dizhi yu kantan* could shape future developments in the field, offering a blueprint for the energy sector to harness the untapped potential of deep saline aquifers.