<p>Cyclic Steam Stimulation (CSS) is a crucial thermal Enhanced Oil Recovery (EOR) technique for heavy crude oil. However, its effectiveness depends on precise parameter optimization and operational design, with CO₂ gas emissions during steam generation often overlooked. This study thoroughly evaluates CSS effectiveness in a heavy oil sandstone reservoir, focusing on eight selected CSS wells. Three of these wells were compared to three wells producing with primary recovery (cold wells), all from the same layer and sharing identical facies and heterogeneity systems. The investigation employs the Chan model to diagnose excessive water production and analyzes well bottom hole pressures using the hydrostatic pressure formula. A novel process is introduced to calculate CO₂ gas emissions from each CSS well's steam generator based on the total energy required for a CSS cycle, measured in Mega Joules (MJ). The comparative analysis reveals that, after five years, total oil production from the CSS wells is 13%, 25%, and 17% lower than that from the cold wells, despite an increase in the cumulative steam injection of 4%, 60%, and 44% for wells 2, 4, and 6, respectively. Additionally, cumulative water production (Wp) from the three CSS wells over the five years is 76% higher than from the cold wells. The combined financial gain from the three CSS wells is only 15.7% of the profit from the three cold wells. CO₂ gas emissions per oil barrel increased with each cycle for the CSS wells. In summary, the results highlight the substantial CO₂ gas emissions associated with CSS operations, underscoring the need for careful consideration in the CSS design process. Despite CSS's effectiveness in enhancing heavy oil recovery, potential drawbacks such as steam channeling and excessive water production necessitate caution. Therefore, continuous review of CSS implementation and exploration of alternative strategies, including a combination of EOR methods and steam additives, are recommended to improve long-term CSS efficiency.</p>