Volume 25: Accelerated Energy Innovations and Emerging Technologies

Optimization of Pore Compressibility Lab-based measurements; Case Study of Supercritical CO2 Exposure and Dissolution Ali ToorajiPour, Hamed Aghaei, Mehdi Escrochi, Milad Farahani, Mohammad Kazem Amiri

Abstract

Injection of carbon dioxide into underground geological formations with proper structure is a common approach performed, such as, for geo-sequestration purposes. During this operation, host rock may then undergo a series of chemical and petrophysical alterations including dissolution and changes in pore structure. Subsequently, knowledge of potential variation in reservoir rock properties against these alterations is of great interest in planning for the geological storage of CO2. Amid these properties is the pore compressibility as a key factor in understanding of rock geomechanical behaviors. However, lab-based analysis of pore compressibility is a challenging procedure with ongoing issues. The present work provides a comparison between two different approaches for lab-based measurement of pore compressibility. The work compares usage of sister plugs and a single one to determine the effect of dissolution and applied pressure on pore compressibility in limestone samples exposed to supercritical CO2. For this purpose, core-flooding experiments with pore-water rich in CO2 were carried out to resemble real reservoir condition while the samples were undergone pore compressibility measurements with the above-mentioned approaches. In the end, it was revealed that using a single plug will provide more precise results compared to the sister plugs, however, attention must be paid to a number of critical parameters. In fact, injection and confining pressures are potential to cause pore closure, and so change the internal structure, during pre-injection pore compressibility measurement. Moreover, in case of using sister-plug approach, it is important to screen the samples based on their pore type and internal structure,

Keywords Limestone, pore volume compressibility, single and sister plugs, supercritical CO2