Speaker
Description
This study addresses the challenge of modeling multiphase flow in complex, multiscale carbonate rocks. Conventional pore network models often assume unresolved (sub-resolution) porosity to be poorly connected or permanently water-saturated. Here, we explicitly distinguish between grain-filling microporosity and pore-filling intermediate-sized pores, whose contributions to flow differ. We show that unresolved porosity, particularly intermediate-sized pores, can be well-connected and play an important role in maintaining flow pathways. Neglecting these pores may therefore lead to incomplete representations of the pore space. To overcome image resolution limitations, we developed a multiscale Generalized Network Model (GNM) that combines a micro-CT–resolved macropore network with an explicit sub-resolution network derived from difference maps between dry and brine-saturated micro-CT images. Sub-resolution porosity is represented using Darcy-type microlinks, capturing connectivity with reduced computational cost. The model is constrained using high-resolution primary drainage capillary pressure–saturation data from differential imaging porous-plate (DIPP) experiments. The framework is applied to two Ketton limestone samples and one reservoir carbonate sample with increasing structural complexity. Results show that including unresolved intermediate-sized pores is necessary to accurately capture pore connectivity and phase distributions. The model reproduces drainage capillary pressure within experimental uncertainty and agrees with published wetting-phase relative permeability data. The approach is further extended to model spontaneous imbibition and forced water injection by incorporating multiscale wettability effects. This work improves predictive capability for multiphase flow in carbonates and is relevant to applications including hydrocarbon recovery, CO₂ sequestration, groundwater flow, and engineered porous systems.
| Country | Turkiye |
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