Microfluidic Devices for Characterizing Pore-scale Event Processes in Porous Media for Oil Recovery Applications

Abstract

Microfluidic devices are versatile tools for studying transport processes at a microscopic scale. A demand exists for microfluidic devices that are resistant to low molecular-weight oil components, unlike traditional polydimethylsiloxane (PDMS) devices. Here, we demonstrate a facile method for making a device with this property, and we use the product of this protocol for examining the pore-scale mechanisms by which foam recovers crude oil. A pattern is first designed using computer-aided design (CAD) software and printed on a transparency with a high-resolution printer. This pattern is then transferred to a photoresist via a lithography procedure. PDMS is cast on the pattern, cured in an oven, and removed to obtain a mold. A thiol-ene crosslinking polymer, commonly used as an optical adhesive (OA), is then poured onto the mold and cured under UV light. The PDMS mold is peeled away from the optical adhesive cast. A glass substrate is then prepared, and the two halves of the device are bonded together. Optical adhesive-based devices are more robust than traditional PDMS microfluidic devices. The epoxy structure is resistant to swelling by many organic solvents, which opens new possibilities for experiments involving light organic liquids. Additionally, the surface wettability behavior of these devices is more stable than that of PDMS. The construction of optical adhesive microfluidic devices is simple, yet requires incrementally more effort than the making of PDMS-based devices. Also, though optical adhesive devices are stable in organic liquids, they may exhibit reduced bond-strength after a long time. Optical adhesive microfluidic devices can be made in geometries that act as 2-D micromodels for porous media. These devices are applied in the study of oil displacement to improve our understanding of the pore-scale mechanisms involved in enhanced oil recovery and aquifer remediation.

Comparing the Coalescence Rate of Water-in-Oil Emulsions Stabilized with Asphaltenes and Asphaltene-like Molecules

“…Flow-focusing microfluidic devices are fabricated with Norland Optical Adhesive (NOA-81), based on a previously published procedure. 32 The devices were rendered oil-wet by using a 5 vol % toluene-based trichloro(octadecyl)silane (OTS, from Sigma-Aldrich, purity ≥ 90%). The OTS solution was injected at 60 μL/min via a syringe pump into the device and allowed to stand for 2 h. Wettability alteration of the NOA-81 was confirmed by contact angle measurements and determined to be 102°(KSV-CAM 200).…”

“…Flow-focusing microfluidic devices are fabricated with Norland Optical Adhesive (NOA-81), based on a previously published procedure . The devices were rendered oil-wet by using a 5 vol % toluene-based trichloro­(octadecyl)­silane (OTS, from Sigma-Aldrich, purity ≥ 90%).…”

A systematic approach to alkaline-surfactant-foam flooding of heavy oil: microfluidic assessment with a novel phase-behavior viscosity map

“…The flow experiments were conducted in micromodels. The micromodels are constructed from NOA 81 polymer (Norland) following a soft-lithography protocol as previously reported in the literature 49 , 50 . This platform was selected because the pore-scale phenomenon of the flow process may be directly observed via a light microscope while simultaneously obtaining pressure-drop data.…”

Exergy return on exergy investment analysis of natural-polymer (Guar-Arabic gum) enhanced oil recovery process

“…In Section "Case study: WAG, SAG and WAG + S" where the oil phase is present, function F oil is introduced to account for the effect of oil on foam. Oil can destabilize foam in porous media by varied mechanisms [15,25,33,63,64]. In this simulation, the parameter floil represent the oil saturation below which oil does not affect foam strength and F oil equals to 1, whereas the parameter fmoil represent the oil saturation above which foam is completely killed and F oil equals to 0.…”