Development of novel microfluidic methodology for investigating mobilisation and displacement mechanisms in enhanced oil recovery processes

The objective in the project will be to develop novel microfluidic methodology for fundamental studies, screening and optimization of mobilization and displacement of crude oil in EOR processes.

Background:

Enhanced oil recovery (EOR) is the final stage in the recovery of crude oil from reservoirs. Much of the oil remaining in the reservoir prior to this stage is microscopically trapped in the pores by capillary action. The amount of remaining oil depends largely on the ratio between the viscous forces displacing the oil and the capillary forces trapping the oil. This ratio (the capillary number) can be kept above a critical value by various chemical EOR processes. These can broadly be divided into the following categories: i) Polymer injection, where the viscous forces are increased by increasing the viscosity of water by polymers ii) Surfactant based injection, where the basic principle is that the surfactant adsorb at the oil-water interface and reduce the capillary forces and iii) Surfactant-Polymer injection, which combine the above effects. In addition, low-salinity water flooding has demonstrated increased oil recovery, either as a stand-alone method or in combination with above processes. In all cases, the interactions between crude oil, brineand reservoir rocks are essential for their efficiency. This means that how much, how fast and how complete oil can be extracted from a reservoir is largely governed by phenomena and processes that occur at the pore level, i.e. at length scales in the micro- to nanometer range.

A microfluidic system is a lab-on-a-chip (or reservoir-on-a-chip) device where micro-volumes of fluids can be controlled and studied in micro-channels or networks of micro-channels, and the fluid behavior often is followed by microscopy methods. This means that the technique is well suited for visualization and fundamental studies of phenomena governing oil mobilization and displacement at length scales where the capillary forces dominate.

Anticipated outcome:
- New microfluidic methodology which will be a relatively rapid, low-cost and highly reproducible way of following oil mobilisation and displacement, and thereby resulting in more efficient screening and optimisation of EOR formulations.
- Improved fundamental knowledge of phenomena and processes that govern oil mobilisation and displacement in porous media.

Better knowledge about how the physicochemical properties of the oil and water phases and the pore properties are linked, which will further improve the fundamental understanding of two-phase flow and displacement mechanisms in porous media.

Photo of the microfluidic setup at Ugelstad Laboratory, NTNU. The inverted microscope connected to the high-speed camera to the left and the stage with syringe pumps to the right