The feasibility of underground injection and storage of CO2 is associated with many technical and economic challenges. Careful engineering design, economic evaluation, and risk assessment are essential steps towards successful implementation of such complex projects. To address some of these issues, reservoir simulations were conducted on different prototypes with properties relevant to potential storage sites in Alberta. The study covers important aspects of injection into two major types of geological formations: saline aquifers and hydrocarbon reservoirs.
In the case of CO2 storage into saline aquifers, the two important studied phenomena were (i) the fate of dissolved H2S in a sour aquifer and (ii) the feasibility of injecting large volumes of CO2 into a very large aquifer.
In the case of CO2 storage in hydrocarbon reservoirs, the feasibility of CO2 EOR/ storage in the tight portion of Pembina Cardium field was studied. Various design parameters and operating conditions can affect the performance of a WAG flood. The parameters considered here are those related to development pattern, hydraulic fracture geometry, WAG parameters and the timing of the switch between different schemes. CO2 EOR performance was assessed based on the oil recovery factor and the amount of stored CO2. However, to reflect the effect of time, the net present value of the projects was also considered. The effect of all parameters on objective functions was investigated using a compositional simulator. Design of experiment was then utilized to perform a comprehensive statistical analysis to recognize the most prominent factors in fulfillment of each objective function. Response surfaces were generated to quantify the effect of the factors on the objective functions. Optimization was carried out to find those sets of factors, which provided the highest recovery, storage, and NPV.
To reduce the uncertainty related to CO2-EOR projects, comprehensive economic studies are required to minimize the risk of failure under different market. Therefore, a rigorous workflow was provided for the industry to evaluate CO2 EOR and storage in tight oil reservoirs. Based on this workflow, it would be possible to quantify the amount of incentives required to make the coupled CO2 EOR and storage economically attractive.