Abstract
AbstractThe phase of CO2 present in a saline reservoir influences the change of the pore geometry properties of reservoir rocks and consequently the transport and storage integrity of the reservoir. In this study, digital rock physics was used to evaluate pore geometry properties of rocks saturated with the different phaseCO2-brine under reservoir conditions. The changes in the pore geometry properties due to the different phaseCO2-brine-rock interaction were quantified. In addition to compression, CO2-brine-rock interaction caused a further reduction in porosity by precipitation. Compared to the dry sample, the porosity of the gaseous CO2-br sample was reduced the most, and was lower by 15% after saturation and compression. There was reduction in the pre-compression porosity after compression for all the samples, however, the reduction was highest in the gaseous CO2-br-saturated sample (13%). The flatness of pore surfaces was reduced, and pores became less rounded after compression, especially in supercritical CO2-br-saturated rock. The results from this research provide a valuable input to guide a robust simulation of CO2 storage in reservoir rocks where different phases of CO2 could be present.
Highlights
Dissolution, residual and capillary trappings are methods of trapping CO2 in a saline reservoir
This research focuses on the changes of the pore geometry properties in the reservoir rocks when saturated with different p haseCO2-brine
The porosity of the br, g CO2-br, scCO2-br, and gCO2 samples was lower by 13%, 15%, 6% and higher by 4%, respectively. These results imply that the presence of brine cause a reduction in porosity of reservoir rocks under stress but this reduction is further accelerated by the presence of C O2 (gCO2-br > scCO2-br), that g CO2-br-saturated sample showed the highest reduction in porosity after saturation and after compression indicates that the process responsible for change in porosity in this research is most active if the C O2 in the brine saline reservoir is gaseous compared to the other phases
Summary
Dissolution, residual and capillary trappings are methods of trapping CO2 in a saline reservoir. This study looks at the effect of different p haseCO2-brine on the pore geometry properties of saline reservoir rocks. Most researches on the effect of C O2 on reservoir properties like Delle Piane and Sarout (2016), Pimienta et al (2017), He et al (2019), Isaka et al (2020) and Huang et al (2020) have assumed that C O2 remains in a single-phase throughout the storage history. It is clear that research on the effect of different phaseCO2-brine on the pore geometry properties of reservoir rocks is lacking. This research sets out to evaluate the changes to the pore geometry of a saline rock due to the different phaseCO2-brine using digital rock physics. This research focuses on the changes of the pore geometry properties (pore volume, shape, flatness, equivalent radius, and sphericity) in the reservoir rocks when saturated with different p haseCO2-brine. Storage modeling studies as well as open up new ways of simulating CO2-brine-rock interaction
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