Development and performance of CO2-responsive foam fracturing fluid

CO2 foam fracturing fluid can effectively integrate CCUS technology into oil and gas field development, and its core advantages include low water consumption, excellent flowback performance, and strong sand-carrying capacity. For these reasons, it has received increasing attention in the oil and gas field development field. However, this type of fracturing fluid still has some prominent problems: The residue from gel breaking can easily cause formation pollution, the system cost is relatively high, and the utilization rate is low, which forms a significant technical bottleneck. In response to these issues, this study, based on the theory of clean fracturing fluid gel breaking without residue and the reusability of CO2-responsive wormlike micelles, innovatively combines CO2-responsive wormlike micelles with different types of surfactant-based foaming agents to construct a new CO2-responsive foam fracturing fluid system. A systematic performance evaluation of the system was conducted to clarify its defoaming rules under different temperature conditions. Compared with the traditional guar gum CO2 foam fracturing fluid, the new system has significant performance advantages. At 90 °C, its foam comprehensive value reached 19720 mL·min, 6150 mL·min higher than the guar gum fluid. After a 5400 s high-temperature and high-shear test at the same temperature, the residual viscosity of the new system was 67 mPa·s, which is higher than the guar gum fluid. This CO2-responsive foam fracturing fluid simultaneously possesses the application potential of both clean fracturing fluid and foam fracturing fluid. It can effectively solve key problems such as formation pollution and low system utilization rates, and laboratory evaluation experiments confirmed its excellent foaming and rheological properties. These results are of great significance for promoting CO2 foam fracturing technology to reach an advanced international level and supporting the low-carbon and high-efficiency development of unconventional oil and gas resources in China.