Optical measurements of oil release from calcite packed beds in microfluidic channels

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.

Roughness induced rotational slowdown near the colloidal glass transition

“…Local ϕ values were calculated by averaging (X,Y) images over a certain Z-range. Otsu's binarization method was used with an intensity threshold that was automatically adjusted per slice 24 . Bright pixels corresponding to fluorescent berries were not separated during intensity thresholding since they typically occupied only ~0.2% of the area per Z slice.…”

Effects of Fluid Aging and Reservoir Temperature on Waterflooding in 2.5D Glass Micromodels

“…34,35 In more holistic approaches, certain types of complexities are integrated into the design of the experiment. To better represent the complex structure of the porous rock medium, dual porosity/depth, 36,37 so-called 2.5D 38,39 and 3D micromodels, 40,41 have been used. Also, microfluidic studies at high temperature and pressure have recently seen the light.…”

“…In more holistic approaches, certain types of complexities are integrated into the design of the experiment. To better represent the complex structure of the porous rock medium, dual porosity/depth, , so-called 2.5D , and 3D micromodels, , have been used. Also, microfluidic studies at high temperature and pressure have recently seen the light. − Although the use of crude oil (CRO) in microfluidic devices has been relatively scarce, a growing trend can be observed here. ,− This has been made possible through the use of chemically resistant chip materials such as glass or silicon.…”

Experimental Investigation on the Pore-Scale Mechanism of Improved Sweep Efficiency by Low-Salinity Water Flooding Using a Reservoir-on-a-Chip

“…10−12 In practice, however, the underlying mechanism and pore-scale flow dynamics in a real reservoir are still not well understood as the water flooding performance and oil configuration in the porous rock still remain unaddressed. 13,14 The unknown mechanisms limit the field application of low-salinity water (LSW) flooding, and this motivated us to investigate the porescale flooding performance and mechanisms. One of the most attractive research areas about low-salinity water flooding is the wettability alteration from oil-wet or neutral-wet to water-wet by reducing the salinity of injected water.…”

“…Low-salinity water flooding (LSWF) is considered as a potential enhanced oil recovery (EOR) method due to its high efficiency and environment friendliness, and a number of studies on this topic have been published in recent years as a result of the growing interest in academia and industry. − In practice, however, the underlying mechanism and pore-scale flow dynamics in a real reservoir are still not well understood as the water flooding performance and oil configuration in the porous rock still remain unaddressed. , The unknown mechanisms limit the field application of low-salinity water (LSW) flooding, and this motivated us to investigate the pore-scale flooding performance and mechanisms.…”