Fracturing shale gas reservoirs with carbon dioxide (CO2) represents an efficient technique in the extraction process. Enhancing the effectiveness of hydrofracturing in these reservoirs necessitates a precise analysis of their heterogeneous nature, mandating the use of 3D reservoir modelling. This modelling approach demonstrates the application of reservoir simulation techniques, crucial for forecasting successful fracturing methods in shale gas recovery. Conducting multi-stage fracturing tests on unconventional reservoirs using this model allows for the assessment of heterogeneity and variations in fracture distance, considering factors like fracture half-length, spacing, and conductivities. Employing CO2 as a fracturing fluid, a simulation study explores diverse conditions. The findings from simulation and modelling indicate a notable enhancement in shale gas recovery rates, exhibiting an increase ranging between approximately 3–7%. These improvements are linked to alterations in fracture half-length, spacing, and the number of fractures.