Two-Phase Flow Simulation and Physical Property Changes at Partial Saturations Using Pore Microstructures of Carbonate Rocks

Abstract:

Carbonate rocks have very heterogeneous structures due to their complex depositional and diagenetic processes. We performed two-phase lattice-Boltzmann flow simulation on high-resolution pore microstructures of two carbonate rocks with different porosity-types: inter-particle and fracture. From the simulations, we obtained detailed distribution of oil and water in the pore space. The distributions of oil-phase showed noticeable difference between drainage and imbibition stages even at the same oil saturation. Fingering effect was well observed in the rock with inter-particle porosity. On the other hand, there was no significant flow near fractures in the sample with fractures. The visualization was very helpful to understand underlying characteristics of oil and water movement in carbonate rocks. We also calculated P-wave velocity and electrical conductivity at different saturations during the two-phase flow simulations. The P-wave velocity and electrical conductivity showed high sensitivity to saturation changes in the sample with fractures, which implies that they can be used to predict the saturation. However, we found very little sensitivity in the sample with inter-particle porosity due to the high frame stiffness. We think that these numerical experiments with digital rocks would be a good complementary tool to understand the characteristics of carbonate reservoir rocks more quantitatively.
Acknowledgements: This research was supported by the Basic Research Project of the Korea Institute of Geoscience and Mineral Resources (KIGAM) funded by the Ministry of Trade, Industry and Energy of Korea (GP2012-029), and “Energy Efficiency & Resources of the Korea Institute of Energy Technology Evaluation and Planning (KETEP) grant” funded by the Ministry of Trade, Industry & energy (No. 20132010201760).