The SaltPreCO2 project aimed to enhance our ability to predict the optimal conditions for injecting carbon dioxide (CO2) into saline aquifers for storage, a critical aspect of carbon capture and storage (CCS) technology. In aquifers, brine occupies the pore spaces in rock, and injected CO2 displaces the brine, essentially turning the system into a large subsurface storage tank. However, increasing the volume of injected CO2, while seemingly beneficial for storing more CO2, can lead to salt precipitation. This precipitation occurs when small salt crystals act as plugs, clogging the pores in the rock and reducing or even preventing gas flow. Moreover, elevated pressure can cause damage to the rock structure, potentially leading to leakage.
To address these challenges, the project conducted laboratory experiments and numerical simulations using rock samples obtained from several candidate storage reservoirs, subjecting them to high pressure-temperature conditions to simulate storage reservoir specifications. The aim was to study the interaction between CO2, brine, and various types of rocks and to understand how the fluid flow, geomechanical and geophysical properties of the rocks change when exposed to CO2 and brine under elavated thermodynamic conditions. Additionally, the project investigated the dynamics of flow through rock samples using miniature systems that pump CO2 and brine, allowing researchers to observe the impact of salt crystals on flow dynamics within the rock.
The project also aimed to develop accurate thermodynamic models and state-of-the-art equipment, such as microfluidic chips and Raman spectroscopy, to simulate reservoir conditions and measure the relevant quantities governing CO2/brine/rock interactions. These efforts were motivated by the need to address the challenges associated with CO2 storage, particularly in saline aquifers, and to improve our understanding of the behavior of injected CO2 and its impact on geological structures.
The motivation behind the project stemmed from the need to address the challenges associated with CO2 storage, particularly in saline aquifers, which are often located close to CO2 sources, making them potentially convenient storage sites. However, the behavior of injected CO2 and its impact on these geological structures were not well understood prior to this research.
The accomplishments of the SaltPreCO2 project include a deeper understanding of salt precipitation processes under high pressure in rock formations, leading to the development of more accurate thermodynamic and reactive transport models. These models have improved the prediction of CO2/brine/rock interactions, ultimately facilitating more efficient and effective storage strategies. Additionally, the project has contributed to the construction of new, advanced equipment and numerical packages capable of simulating reservoir conditions, further enhancing our ability to study and manage CO2 storage processes.