3D Visualization of Oil Displacement in Porous Media by the Injection of Microcapsule Suspension using Confocal Microscopy

Abstract

In the past decades, oil companies have shown growing interest in increasing oil recovery efficiency. Commonly, after primary and secondary recovery phases, a large amount of oil remains trapped inside the reservoir. Thus, the number of studies focused on enhanced oil recovery is growing, aiming to increase the recovery factor. The focus of this work is to study the fundamentals of oil displacement in porous media using a confocal laser scanning microscope, which enables 3D visualization of dynamic phenomena with a good spacial and time resolution. The analysis was on oil displacement that results from the use of a suspension of gellan gum microcapsules in water injected after water injection. These microcapsules moving along with the water, blocked some of the preferential paths and forced the water to displace trapped oil ganglia. The result achieved was a collection of 3D images from artificial porous media, in which it was possible to distinguish the distribution of phases (microcapsules, oil, and aqueous phases) inside the porous media, before and after the microcapsules injection. These images showed that indeed the gellan gum microcapsules blocked preferential water paths and that, after the blockage, some oil ganglia were displaced from their original positions. This work applied modern techniques of microscopy to investigate the concept behind enhanced oil recovery using microcapsules.

Exploring Potential of Gellan Gum for Enhanced Oil Recovery

“…The injection of the microcapsules into 38%-porosity and 232D-permeability homogeneous porous media made of glass spheres allowed for the mobilization of residual oil saturation (immobile oil), which was visually proven by using confocal microscopy (Figure 15). In fact, it was shown that within an 11 mm-length porous model, the injection of microcapsules allowed for a reduction in the residual oil saturation from 32.9 to 25.7% [69]. Unfortunately, the images presented in the paper demonstrate that even in high-permeability porous channels, the deep penetration of microcapsules is problematic.…”

“…Moreover, no pressure gradient data were presented in this paper; however, from the figure above, it is evident that the gel microcapsules plug the porous media. Almost in all tests, the gellan gum was injected in the form of a solution; however, in [69], the gellan gum was used to prepare 104 µm-diameter microcapsules with a soft 5 µm-thickness shell, which presumably allowed for better penetration into 120-200 µmsize pores [69]. The injection of the microcapsules into 38%-porosity and 232D-permeability homogeneous porous media made of glass spheres allowed for the mobilization of residual oil saturation (immobile oil), which was visually proven by using confocal microscopy (Figure 15).…”