CO2-energized fracturing holds great potential for enhancing fracturing fluid flowback and enabling effective CO2 sequestration, while the effect of the choice of CO2 energization strategy on these processes is not yet fully understood. This study experimentally investigated three representative CO2 energization methods: Pre-fracturing injection, foam injection, and co-injection. Nuclear magnetic resonance techniques were applied to systematically analyze the influence of various CO2 injection parameters on fracturing fluid flowback behavior and CO2 storage in tight formations. The results showed that CO2 pre-fracturing increases displacement pressure and significantly improves flowback efficiency, with optimal performance achieved at a moderate injection volume. Reducing the injection rate and increasing the volume further enhanced the CO2 storage ratio. Foam injection facilitated flowback by improving foam quality, particularly in macropores. Co-injection achieved a favorable balance between high flowback efficiency and substantial CO2 retention. Furthermore, the three energization strategies were shown to lead to distinct fluid redistribution patterns within porous media: Pre-fracturing promoted CO2 retention in micropores and mesopores, foam injection reduced retention in macropores, and co-injection provided the most balanced performance in mesopores. These findings provide new insights into CO2-energized fracturing and sequestration mechanisms and offer technical guidance for optimizing CO2-based stimulation strategies in deep unconventional tight gas reservoirs.
Publications
- Article type
- Year
- Co-author
Article type
Year
Open Access
Original Article
Issue
Advances in Geo-Energy Research 2026, 19(1): 58-71
Published: 03 January 2026
Downloads:31
Total 1
京公网安备11010802044758号