Visual Understanding of Rock Wettability Distribution to Contact Angle Regions and Oil Displacement Patterns in the Silty Sand Reservoir via 2D Pore-Scale Modeling

Abstract This study, conducted using a silty sand reservoir rock extracted from a Kuwait-producing oilfield, provides crucial insights into fluid distribution patterns and mineralogy, as well as wettability contact angle preferences. The method used for visual identification not only captures rock physics but also suggests effective oil recovery displacement strategies. Visual identification is presented using 2D image technology and a Scanning Electron Microscope (SEM). Analytical data are presented from electron bombardments and backscattering reflections collected in the BSE detector. These analyses were used to characterize the various surface boundary morphology parameters of the silty sand mineral surfaces, including area, perimeter, mineral surface angles, and pore counts. Further necessary morphological measurements are length, width, and the static wettability contact angle between pore and grain spaces across the sample. The pore-wall wettability contact angle is accurately quantified by acquiring pore-scale images and original fluid distribution and capturing all counted pores. The 2-D approach has identified eighteen regions of fluid distribution patterns, of which about 38% are newly detected wettability regions, considering the geometrical contact angle mirror effect. The morphological statistical pore parameters are counted for 1,877 objects of pores at an X40 magnification level, with pore areas ranging from 7.8 µm² to 713,905.3 µm². This magnification level captures the most significant wettability-measured feature from the silty sand rock. The overall pore-grain wall wettability preference is medium water wet (MWW) with an overall averaged wettability contact angle of 35.35°, which makes the silty sand rock a candidate for secondary water displacement treatments. This research has significant implications for the petroleum industry, particularly in understanding the wettability contact angle distribution within reservoir rock, a critical factor in Al-Bazzaz's models. It will inspire and guide any future crude oil development in this field, opening new possibilities for cost-effective oil recovery strategies during the life cycle of this reservoir.