Abstract
To enable the study of improved oil recovery (IOR) from carbonate rock via laboratory experiments at the pore scale, we have developed a novel microfluidic chip containing a 3D packed bed of calcite particles. The utilization of fluorescently labeled water phase enabled visualization up to 1–2 particle layers with confocal laser scanning microscopy. Porosity and residual oil saturation (ROS) in this space are quantified from image stacks in the depth direction (Z). To obtain reliable average ROS values, Z stacks are captured at various XY locations and sampled over several time-steps in the steady state. All image stacks are binarized using Otsu’s method, subsequent to automated corrections for imperfect illumination and Z-drifts of the microscope stage. Low salinity IOR was mimicked using a packed bed that was initially saturated with water and then with mineral oil. Steady state ROS values showed no significant dependence on capillary number (Ca) in the range from 6 × 10–7 to 2 × 10–5. In contrast, chemical modification of the pore space via adsorption of water-extracted crude oil components yielded significantly higher ROS values, in agreement with a more oil-wet porous medium. These results indicate a good potential for using packed beds on a chip as an efficient screening tool for the optimization and development of different IOR methods.
Highlights
Despite decades of research and development, the efficient recovery of oil from reservoir rock remains a challenging problem
We will show that a packed-bed microfluidic chip, combined with our image analysis method, allows to detect changes in residual oil saturation (ROS) caused by changes in the waterflooding physicochemical conditions
Further data analysis was performed automatically with Matlab codes to quantify the area fraction of fluorescein-dyed water per individual image. By averaging this fraction over the different Z slices while taking into account all (X, Y) regions of interest (ROI), an average water volume fraction, representative for the packed bed is calculated as a function of time
Summary
Despite decades of research and development, the efficient recovery of oil from reservoir rock remains a challenging problem. Even with current improved oil recovery (IOR) methods, a significant volume of the oil typically remains behind in the reservoir (Sheng 2013). A comprehensive understanding of how SWF works is still lacking, as evidenced by scattered results from different field studies in clastics, (Bartels et al 2019) and ongoing debates on underlying mechanisms in the scientific literature (Hao et al 2019), in particular to carbonate reservoirs. Convergence towards a unified understanding has been hampered by the difficulty to acquire experimental data that allow straightforward analysis on the effect of
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Free) 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call
