A modelling study to evaluate the effect of impure CO2 on reservoir performance in a sandstone saline aquifer

Abstract

Carbon capture and storage (CCS) is expected to play a key role in meeting greenhouse gas emissions reduction targets. In the UK Southern North Sea, the Bunter Sandstone formation (BSF) has been identified as a potential reservoir which can store very large amounts of CO 2 . The formation has fairly good porosity and permeability and is sealed with both effective caprock and base rock, making CO 2 storage feasible at industrial scale. However, when CO 2 is captured, it typically contains impurities, which may shift the boundaries of the CO 2 phase diagram, implying that higher costs will be needed for storage operations. In this study, we modelled the effect of CO 2 and impurities (NO 2 , SO 2 , H 2 S) on the reservoir performance of the BSF. The injection of CO 2 at constant rate and pressure using a single horizontal well injection strategy was simulated for up to 30 years, as well as an additional 30 years of monitoring. The results suggest that impurities in the CO 2 stream affect injectivity differently, but the effects are usually encountered during early stages of injection into the BSF and may not necessarily affect cumulative injection over an extended period. It was also found that porosity of the storage site is the most important factor controlling the limits on injection. The simulations also suggest that CO 2 remains secured within the reservoir for 30 years after injection is completed, indicating that no post-injection leakage is anticipated.

Review on Experimental Investigation into Formation Damage during Geologic Carbon Sequestration: Advances and Outlook

“…The experiment of Zhao et al showed that pore structures were affected during CO 2 injection, in which the precipitation of secondary minerals changed the sorting behavior of the rock formation, especially the pore throats, causing the permeability to decline . The change in pore throats is because of the strong precipitation of carbonate minerals, feldspar and quartz. ,,,− The results of the experiment of Zhao et al. are presented in Figure .…”

Advances in Carbon Dioxide Storage Projects: Assessment and Perspectives

“…CO 2 storage in geological formations is considered to be an effective option to store it permanently and safely . The geological formation used includes deep saline aquifers, depleted oil and gas fields, storage in basalts, storage in coal, deep ocean, and hydrate formation . However, the main driving factor used to assess the storage requirements for the location include depth of the formation (more than 800 m), storage capacity, permeability and porosity, physical leakage, hydrogeology conditions, and seismicity activities …”