Impact of Non-Condensable Gas Selection on CO2 Mitigation and Economic Viability in Steam and Gas Push

초록

In the oil sands industry of Canada, steam-assisted gravity drainage (SAGD) is a major source of greenhouse gas (GHG) emissions, primarily due to its reliance on combustion of natural gas for steam. Lowering the cumulative steam-oil ratio (cSOR) is crucial for reducing emissions, with steam and gas push (SAGP) emerging as a viable alternative. This study conducted a sensitivity analysis of non-condensable gas (NCG) types-methane, nitrogen, and carbon dioxide (CO2)-at mole fractions of 0.1, 0.5, 1.0, 2.0, and 4.0 mol%, using a three-dimensional (3D) heterogeneous reservoir model. Among these, the 0.1 mol% CO2 case yielded the lowest cSOR (2.39), demonstrating its effectiveness as an NCG in SAGP. The economic viability of SAGD and SAGP was assessed under the Canadian carbon tax policy using a net present value (NPV) analysis. Because SAGD exhibited the highest carbon emission intensity (0.75 tonCO2eq/m3), it was most affected by the carbon tax. Contrastingly, SAGP demonstrated lower carbon emission intensity (CH4 0.5 mol%, 0.51 tonCO2eq/m3; N2 0.5 mol%, 0.57 tonCO2eq/m3; CO2 0.1 mol%, 0.55 tonCO2eq/m3), mitigating the economic impact of the carbon tax. The 0.1 mol% CO2 case achieved the highest NPV ($13.97MM),a324.62$3.29 MM). Furthermore, NPV increased when stored CO2 was considered for carbon sequestration. These results suggest that using CO2 in SAGP can enhance both environmental and economic performance compared with those of the previously preferred NCG types such as methane and nitrogen. This study confirms the potential of CO2 as a viable NCG not merely for storage, but also for use in oil sands production, particularly under carbon tax policies.

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