<p>The rock fracture is fundamental to understanding the rock strength and predicting failure behavior in heterogeneous reservoirs. A weak rock exhibits frequent initiation and propagation of fractures, making it unsuitable for applications where strength is required. The prolonged storage of carbon dioxide in the porous rock depends on the fracture behavior of the reservoir and cap rock. Therefore, it is crucial to emphasize the fractured behavior of cap rock for the successful injection and storage of CO₂ in unconventional reservoirs. A shale sample obtained from Jarangdih Coalfield in Bokaro, Jharkhand, India, was considered for analysis as cap rock. The crack initiation and propagation in shale surfaces were analyzed in this study using the Extended Finite Element Method (XFEM) using a numerical analysis approach. The crack growth analysis at variable inlet pressure and fracture energy is reported in this study. The XFEM model successfully captured the transition from stable to unstable crack growth. The effect of Applied pressure, principal stress, strain, etc., on crack growth in the cap rock surface is reported in detail. A slight variation in the applied pressure is reflected in terms of the drastic failure of the rock. Mutual correlations were established between the applied pressure and the factors influencing crack growth to identify the most critical factors contributing to failure.</p>