When CO2 is injected into a deep saline aquifer, there exists a risk of cap fracture and wellbore breakthrough due to overpressure. Monitoring the geomechanical changes in the cap layer and reservoir is of great significance for evaluating the stability of CO2 injection. Distributed acoustic sensing (DAS), which can sensitively capture weak strain changes has become a new technology for CO2 storage monitoring. Based on the CO2 storage conceptual model, numerical simulation research on reservoir strain response during CO2 injection under different injection volumes and reservoir permeability were carried out. CO2 saturation, strain and wellbore pressure at monitoring points are taken as sample data. CO2 leakage warning models based on multi-layer perceptron (MLP), convolutional neural network (CNN) and Dual CNN architecture were established. The results show that the CO2 breakthrough and leakage warning model based on MLP, CNN and Dual CNN can effectively warn CO2 breakthrough and leakage, and the accuracy rate is higher than 98%. The research results provide a new method for monitoring and warning CO2 leakage by DAS in CCUS.
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