Microfluidic Investigation of Nanoparticles’ Role in Mobilizing Trapped Oil Droplets in Porous Media

Abstract

The flow of multiple fluid phases in porous media often results in trapped droplets of the nonwetting phase. Recent experimental and theoretical studies have suggested that nanoparticle aqueous dispersions may be effective at mobilizing trapped droplets of nonwetting fluid (oil) in porous media. Hypotheses to explain the observation include the nanoparticles' modification of solid wettability, droplet stabilization, and changes in interfacial tension and interface rheology. However, because it is difficult to observe droplet behavior on the pore scale, how those factors contribute to oil droplet mobilization has not been fully understood. In this work, we investigated the nanoparticles' role in nanoparticle-based improved recovery of the nonwetting phase through the direct observation of the mobilization of trapped oil droplets in microfluidic structures that mimic pore-throat geometries. A microfluidic platform was constructed for this study, on which different displacing liquids including aqueous surfactant solutions and nanoparticle suspensions were tested. We found that the nanoparticle concentration is positively related to the oil mobilization efficiency. An approximate mathematical model for calculating the maximum size of an oil droplet trapped in a pore-throat geometry for a fixed flow rate matches the experiment result for displacing liquid with no nanoparticles. The model still holds when the nanoparticle suspension is a displacing liquid. We concluded that nanoparticles mobilize oil in these geometries in a mechanism similar to that for surfactants, which is an increase in capillary number rather than an effect of other fluidic or interfacial properties such as the dynamics adsorption of nanoparticle or dilational rheology of a nanoparticle-adsorbed interface.

Retention of Nanoparticles: From Laboratory Cores to Outcrop Scale

“…Our rationale for using an analogous relationship is to obtain a realistic range of retention constant values in a two-site model at disparate scales. This empirical relation, given by (9), is based on mechanisms of deposition, interception, and sedimentation [36,38,51,70]:…”

“…Even though they have been widely used in various industries such as the medical field for enhanced imaging [1,2], targeted drug-delivery, and biosensing [3][4][5], NPs have yet to be adapted for their potentially attractive application in porous media. These applications may include enhanced hydrocarbon recovery through nanosuspensions [6][7][8][9], subsurface mapping through nanosensors [10,11], hydraulic fracture characterization through nanomagnetization of reservoirs [12], hydraulic fracturing fluid with better proppant transport ability through nanofoams [13], and convective heat transfer [14,15]. Many of these applications within porous media, such as enhanced oil recovery and subsurface mapping, would require the NPs to travel the depth and breadth of the targeted reservoir zone, which typically extend to hundreds of feet.…”

A review study on micro fluid chips for enhancing the oil recovery by injecting the chemical floods

“…It has been implemented to investigate different multi-phase flow phenomena in porous media at the pore level. Due to some recent advancement in micromodel chips, such as design of single-channel patterns with variable cross-section size, it provides opportunity to study the emulsion flow in parallel conduits [7], trapping of non-wetting phase at pore-throat structures and geometries pertinent to enhanced oil recovery [8] and the research in reservoir engineering. Additionally, 2-D and 3-D features in the micromodel geometry has been developed and commonly used but both have some limitations.…”

“…while in (3-D), physics is required in porous media especially for multi-phase flow where capillary effects are prominent, resolution and material limit, and 3-D printing technology [11]. Unfortunately, these limitations make it unmanageable to construct a 3-D micromodel as a basic model of truly micron-scale permeable medium [7,12].…”

Transport mechanism of deformable micro-gel particle through micropores with mechanical properties characterized by AFM

“…Due to the strong reservoir heterogeneity and fluid channeling, it is reported that the normal water flooding can only produce about 30% of the total reserves of oil 3 . To overcome these difficulties, several EOR techniques have been proposed, including polymer flooding 3–5 , oil-in-water (O/W) emulsions 6,7 and foam displacement 8 . Among these techniques, polymer flooding is considered as one of the most promising technologies 9 .…”