The impact of formation characteristics on CO2 sequestration into an aquifer



With the increasing trends in global temperature and CO2 emissions, there is expanding interest in geological storing as potential sites for the safe and fast disposal of CO2. This expanding interest necessitates the need of studying the effects of geological parameters on CO2 sequestration. The processes that occur in CO2 sequestration are complex with many different parameters influencing the behavior of the injected CO2 and therefore numerical simulations are required.

The objective of this research is to study the impact of the aquifer properties and operational parameters to understand the CO2 plume behavior and their contribution to various trapping mechanisms. Such study will help minimize uncertainty in estimates of the capacity and injectivity of CO2. In order to accomplish these objectives, selection of a set of representative characteristics for an aquifer as base case was first modeled. Next variation of injection schemes and rates were modeled to evaluate CO2 plume behavior and the potential of CO2 storage volume.

In addition this study demonstrates how different trapping mechanisms are influenced by variation of reservoir properties and dip angle. These studies show that bottom injection of CO2 at high rates for a slight dipping aquifer has a significant impact on the total amount of CO2 injected, dissolved and trapped in the aquifer. Bottom completion and high-rate injection allow more CO2 to be injected and the plume to come into contact with larger amount of brine due to buoyancy effect and larger distribution of the plume, which will enhance solubility and residual trapping mechanisms. Temperature and pressure have a slight impact on the solubility of CO2. The results also show that reservoir permeability has a large impact on the dissolved and trapped CO2, as it facilitates the lateral migration of CO2 enhancing dissolution into the brine.



Figure 8: Relevant Transport Processes of CO2

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