The Study Of Fluids Flow Through Porous Media Using Microfluidic Devices

Download or read book The Study of Fluids Flow-through Porous Media Using Microfluidic Devices written by Feng Guo and published by . This book was released on 2019 with total page 148 pages. Available in PDF, EPUB and Kindle. Book excerpt: The goal of this research is implementing glass-fabricated microfluidic devices to study problems involving fluid flow through porous media problems, including; foam flooding in enhanced oil recovery (EOR), immiscible displacement instability, and CO2 sequestration in a deep saline aquifer. The relatively low viscosity and density of CO2 causes severe fingering, gravity override and high mobility through high permeability layers or fractures, which leads to low sweep efficiency in porous media. CO2 foam flooding stabilized by nanoparticles (NPs) is able to significantly increase CO2 injectant apparent viscosity thereby reducing its mobility and increasing the volumetric sweep efficiency in EOR and sequestration. A deep understanding of flow behaviors and displacement instabilities of CO2 (foam and gas) in porous media enhances the ability to predict oil recovery and CO2 storage and inform reservoir engineering decisions. This dissertation provides details of experimental work performed in NP-stabilized CO2 foam flooding, immiscible displacements and CO2 sequestration using different fabricated microfluidic devices. Several novel NPs candidates are investigated and evaluated in terms of foam stability and oil recovery. The flow behavior of CO2 foam and the resulting incremental oil recovery are investigated in both homogeneous and heterogeneous porous media. Flow instabilities and phase diagrams with boundaries of three flow regimes of immiscible displacement are investigated. In addition, the CO2 gas/foam storage capacity and efficiency in a deep saline aquifer are studied. In order to study NP-stabilized CO2 foam flooding in porous media, a homogeneous microfluidic device is fabricated in which the pore network is based on a 2D representation of a sample of Berea sandstone. Foam properties of NPs stabilized CO2 foam using silica (Si), nanoclay, fly ash and iron oxide (IO) and the resulting improvement in oil recovery are investigated using a series of modified bulk foam tests and microfluidic experiments. Results show that the size and/or size distribution, shape, and surface charge of the particles are influential parameters governing the foam stability and formability which have a direct relationship with oil recovery performance. The displacement observation shows the silica and fly ash NPs assisted by surfactant mixture (Alpha-Olefin Sulfonate (AOS)-Lauramidopropyl Betaine (LAPB)) generated stable foams and resulted in high ultimate oil recoveries (over 90%). Even though IO-surfactant mixtures generate foams with relatively inferior stability characteristics and ultimate recovery, approximately three quarters of the IO NPs are recovered once exposed to a magnetic field. Recovered IO NPs have the potential to be reused in EOR process. The implement of by-product fly ash and recyclable IO NP provides potential advantage of NPs on a commercial scale in EOR processes. A heterogeneous microfluidic device is fabricated, which consisted of a centrally located low permeability zone and two high permeability zones on its sides, to study flow behaviors of CO2 foam and its impact on mobility control in displacing oil in a heterogeneous porous medium. The results show that foam is able to mobilize and recover oil trapped in the low permeability zone by increasing the resistance to flow in the high permeability zones and diverting the surfactant solution into the adjacent low-permeability zone. Foam remains gas-rich in the high permeability zones and solvent-rich in the low permeability zone throughout the experiments. The observed displacement dynamics are explained by characterizing channel geometries (trapezoid) and calculating capillary entry pressure values for various fluids and zones of the medium. Flow behaviors and instabilities in two phase immiscible displacements are addressed using a glass microfluidic device. A series of microfluidic device immiscible displacement experiments are conducted across a range of capillary numbers (Ca) of 1E-4 to 9E-8 and viscosity ratio (M) from 1E-4 to 13.6E3. The microfluidic device features a water-wet porous medium based on a two-dimensional representation of a Berea sandstone; the displacement processes are captured using a high-resolution camera that allows visualization of the entire domain, while being able to resolve features as small as 10 μm. The study reports a correlation between fractal dimension of displacement fronts and displacement front patterns in the porous medium. Three flow regimes with boundaries are mapped on a two-dimensional parameter space (log M and log Ca), and phase diagrams proposed in the literature are superimposed for comparison. Results suggest that the transition regime may occupy a much larger region of the flow regime diagram than is suggested in recent literature. This two-phase immiscible displacement study not only extended works of previous studies using an advanced glass microfluidic device but also it may also help understand macroscopic processes at the continuum scale and provide insights into designing engineered porous media such as exchange columns and membranes with respect to desired immiscible displacement behaviors. In order to study CO2 sequestration in an aquifer with multiple variables, namely, fluids’ interfacial tension, injection rate, viscosity and the characteristics of the porous medium, a custom microfluidic device is developed. The pore network is based on a mosaic of Scanning Electron Microscopy (SEM) images of a thin section of the Lower Cretaceous Washita-Fredericksburg, which is a saline aquifer-bearing formation in east-central Mississippi, USA. The study investigates the effects of those variables on CO2 gas and foam injection into the brine-saturated porous medium. The results suggest that higher injection rates and CO2 foam injection are able to improve CO2 saturation, and therefore storage, in the microfluidic device; ultimate CO2 saturation from foam injection are approximately 20%-40% higher compared to results from gas injection. Thus, CO2 foam injection is a promising approach to reduce CO2 mobility and optimize the CO2 storage capacity in saline aquifer formations. In addition, legislation of CO2 sequestration and potential advantages of using CO2 foam for geological CO2 sequestration in the aforementioned saline aquifer, which is currently under study for commercial-scale CO2 storage, are also discussed. This research study shows advantages of using glass fabricated microfluidic devices with complex configurations to study several flow-through porous media problems. It enables visualization of fluids distributions and displacement fronts inside various porous media, therefore, providing insights into microscale displacement processes help elucidate fundamental mechanisms responsible for the observed flow behaviors.