Dual-Wetting Porous Plate System to Measure Drainage and Imbibition Capillary Pressure: A Case Study on a Complex Reservoir Carbonate

Capillary pressures data are essential for understanding the initial fluid distribution in reservoirs prior to production (Primary drainage) or for predicting oil recovery during waterflooding processes (first imbibition). Coupled with Digital Rock Physics tools, these properties also provide valuable pore-scale insights into rock’s topology and wettability distribution within the pore network. Recent studies have demonstrated the predictivity of pore network multiphase flow simulations when accurate pore-scale wettability observations are performed, on simple and permeable rocks. Trying to understand different wettability patterns becomes even more important when dealing with complex rocks where a significant amount of porosity is below the resolution of 3D images. This paper introduces a dual-wetting porous plate system designed to measure both drainage and imbibition capillary pressure curves on the same rock, under constant experimental conditions, including wettability alteration. The PEEK cell is X-ray transparent, enabling 3D saturation monitoring via micro-CT, and is adaptable to SCAL protocols. Validation was performed on a 20mD complex carbonate reservoir rock, including wettability alteration with crude oil. Primary drainage and first imbibition capillary pressure curves were first both derived numerically with a conventional Unsteady State relative permeability experiment on a large sample. In a second time, we used a mini plug from the same SCAL sample’s depth, to derive primary drainage and imbibition capillary pressure curves with our dual-wetting porous plate system, under identical experimental conditions than the SCAL experiment. The results showed good agreement between the SCAL and our DRP experiments, confirming the proof of concept of the system. Additionally, 3D images processing of the mini plug enabled observation of the sequence of invasion of different porosity textures, providing insights into wettability distribution. This experimental design offers valuable input for understanding the impact of wettability patterns on multiphase flow properties.