High‐Speed Quantification of Pore‐Scale Multiphase Flow of Water and Supercritical CO
            2
            in 2‐D Heterogeneous Porous Micromodels: Flow Regimes and Interface Dynamics

Summary Wettability is a major factor that influences multiphase flow in porous media. Numerous experimental studies have reported wettability effects on relative permeability. Laboratory determination for the impact of wettability on relative permeability continues to be a challenge because of difficulties with quantifying wettability alteration, correcting for capillary-end effect, and observing pore-scale flow regimes during core-scale experiments. Herein, we studied the impact of wettability alteration on relative permeability by integrating laboratory steady-state experiments with in-situ high-resolution imaging. We characterized wettability alteration at the core scale by conventional laboratory methods and used history matching for relative permeability determination to account for capillary-end effect. We found that because of wettability alteration from water-wet to mixed-wet conditions, oil relative permeability decreased while water relative permeability slightly increased. For the mixed-wet condition, the pore-scale data demonstrated that the interaction of viscous and capillary forces resulted in viscous-dominated flow, whereby nonwetting phase was able to flow through the smaller regions of the pore space. Overall, this study demonstrates how special-core-analysis (SCAL) techniques can be coupled with pore-scale imaging to provide further insights on pore-scale flow regimes during dynamic coreflooding experiments.

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Quantifying the Dynamics of Water-CO2 Multiphase Flow in Microfluidic Porous Media Using High-Speed Micro-PIV

Volume 10: Fluids Engineering ◽

10.1115/imece2020-24545 ◽

2020 ◽

Author(s):

Yaofa Li ◽

Gianluca Blois ◽

Farzan Kazemifar ◽

Kenneth T. Christensen

Keyword(s):

Porous Media ◽

Multiphase Flow ◽

High Speed ◽

Flow In Porous Media ◽

Low Flow ◽

Scale Model ◽

Pore Scale ◽

Micro Piv ◽

Liquid Co2 ◽

The Impact

Abstract Multiphase flow in porous media is central to a large range of applications in the energy and environmental sectors, such as enhanced oil recovery, groundwater remediation, and geologic CO2 storage and sequestration (CCS). Herein we present an experimental study of pore-scale flow dynamics of liquid CO2 and water in two-dimensional (2D) heterogeneous porous micromodels employing high-speed microscopic particle image velocimetry (micro-PIV). This novel technique allowed us to spatially and temporally resolve the dynamics of multiphase flow of CO2 and water under reservoir-relevant conditions for varying wettabilities and thus to evaluate the impact of wettability on the observed physics and dynamics. The preliminary results show that multiphase flow of liquid CO2 and water in hydrophilic micromodels is strongly dominated by successive pore-scale burst events, resulting in velocities of two orders of magnitude larger than the bulk velocity. When the surface wettability was altered such that imbibtion takes place, capillarity and instability are significantly suppressed, leading to more compact and axi-symmetric displacement of water by liquid CO2 with generally low flow velocities. To our knowledge, this work represents the first of its kind, and will be useful for advancing our fundamental understanding and facilitating pore-scale model development and validation.

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The Origin of Non-thermal Fluctuations in Multiphase Flow in Porous Media

Frontiers in Water ◽

10.3389/frwa.2021.671399 ◽

2021 ◽

Vol 3 ◽

Author(s):

Maja Rücker ◽

Apostolos Georgiadis ◽

Ryan T. Armstrong ◽

Holger Ott ◽

Niels Brussee ◽

...

Keyword(s):

Multiphase Flow ◽

Pressure Fluctuations ◽

Flow Theory ◽

Flow Regimes ◽

Energy Scale ◽

Dynamic Imaging ◽

Pore Scale ◽

Fractional Flow ◽

Flow Experiments ◽

Fractional Flow Theory

Core flooding experiments to determine multiphase flow in properties of rock such as relative permeability can show significant fluctuations in terms of pressure, saturation, and electrical conductivity. That is typically not considered in the Darcy scale interpretation but treated as noise. However, in recent years, flow regimes that exhibit spatio-temporal variations in pore scale occupancy related to fluid phase pressure changes have been identified. They are associated with topological changes in the fluid configurations caused by pore-scale instabilities such as snap-off. The common understanding of Darcy-scale flow regimes is that pore-scale phenomena and their signature should have averaged out at the scale of representative elementary volumes (REV) and above. In this work, it is demonstrated that pressure fluctuations observed in centimeter-scale experiments commonly considered Darcy-scale at fractional flow conditions, where wetting and non-wetting phases are co-injected into porous rock at small (<10−6) capillary numbers are ultimately caused by pore-scale processes, but there is also a Darcy-scale fractional flow theory aspect. We compare fluctuations in fractional flow experiments conducted on samples of few centimeters size with respective experiments and in-situ micro-CT imaging at pore-scale resolution using synchrotron-based X-ray computed micro-tomography. On that basis we can establish a systematic causality from pore to Darcy scale. At the pore scale, dynamic imaging allows to directly observe the associated breakup and coalescence processes of non-wetting phase clusters, which follow “trajectories” in a “phase diagram” defined by fractional flow and capillary number and can be used to categorize flow regimes. Connected pathway flow would be represented by a fixed point, whereas processes such as ganglion dynamics follow trajectories but are still overall capillary-dominated. That suggests that the origin of the pressure fluctuations observed in centimeter-sized fractional flow experiments are capillary effects. The energy scale of the pressure fluctuations corresponds to 105-106 times the thermal energy scale. This means the fluctuations are non-thermal. At the centimeter scale, there are non-monotonic and even oscillatory solutions permissible by the fractional flow theory, which allow the fluctuations to be visible and—depending on exact conditions—significant at centimeter scale, within the viscous limit of classical (Darcy scale) fractional flow theory. That also means that the phenomenon involves both capillary aspects from the pore or cluster scale and viscous aspects of fractional flow and occurs right at the transition, where the physical description concept changes from pore to Darcy scale.

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Pore-Scale Dynamics of Liquid CO2–Water Displacement in 2D Axisymmetric Porous Micromodels Under Strong Drainage and Weak Imbibition Conditions: High-Speed μPIV Measurements

Frontiers in Water ◽

10.3389/frwa.2021.710370 ◽

2021 ◽

Vol 3 ◽

Author(s):

Yaofa Li ◽

Gianluca Blois ◽

Farzan Kazemifar ◽

Razin S. Molla ◽

Kenneth T. Christensen

Keyword(s):

Surface Energy ◽

Multiphase Flow ◽

High Speed ◽

Flow Instability ◽

Flow Dynamics ◽

Flow In Porous Media ◽

Pore Scale ◽

External Work ◽

Direct Observations ◽

Filling Mechanism

Resolving pore-scale transient flow dynamics is crucial to understanding the physics underlying multiphase flow in porous media and informing large-scale predictive models. Surface properties of the porous matrix play an important role in controlling such physics, yet interfacial mechanisms remain poorly understood, in part due to a lack of direct observations. This study reports on an experimental investigation of the pore-scale flow dynamics of liquid CO2 and water in two-dimensional (2D) circular porous micromodels with different surface characteristics employing high-speed microscopic particle image velocimetry (μPIV). The design of the micromodel minimized side boundary effects due to the limited size of the domain. The high-speed μPIV technique resolved the spatial and temporal dynamics of multiphase flow of CO2 and water under reservoir-relevant conditions, for both drainage and imbibition scenarios. When CO2 displaced water in a hydrophilic micromodel (i.e., drainage), unstable capillary fingering occurred and the pore flow was dominated by successive pore-scale burst events (i.e., Haines jumps). When the same experiment was repeated in a nearly neutral wetting micromodel (i.e., weak imbibition), flow instability and fluctuations were virtually eliminated, leading to a more compact displacement pattern. Energy balance analysis indicates that the conversion efficiency between surface energy and external work is less than 30%, and that kinetic energy is a disproportionately smaller contributor to the energy budget. This is true even during a Haines jump event, which induces velocities typically two orders of magnitude higher than the bulk velocity. These novel measurements further enabled direct observations of the meniscus displacement, revealing a significant alteration of the pore filling mechanisms during drainage and imbibition. While the former typically featured burst events, which often occur only at one of the several throats connecting a pore, the latter is typically dominated by a cooperative filling mechanism involving simultaneous invasion of a pore from multiple throats. This cooperative filling mechanism leads to merging of two interfaces and releases surface energy, causing instantaneous high-speed events that are similar, yet fundamentally different from, burst events. Finally, pore-scale velocity fields were statistically analyzed to provide a quantitative measure of the role of capillary effects in these pore flows.

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NUMERICAL SIMULATION OF INTERFACE AND PLUME FORMATION IN HIGH-SPEED MULTIPHASE FLOW

10.1615/tfec2017.mns.018638 ◽

2017 ◽

Author(s):

Carlton P. Adam ◽

Hamid Hadim

Keyword(s):

Numerical Simulation ◽

Multiphase Flow ◽

High Speed

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A New Waterflood Initialization Protocol With Wettability Alteration for Pore-Scale Multiphase Flow Experiments

Petrophysics – The SPWLA Journal of Formation Evaluation and Reservoir Description ◽

10.30632/pjv60n2-2019a4 ◽

2019 ◽

Vol 60 (2) ◽

pp. 264-272 ◽

Cited By ~ 3

Author(s):

Qingyang Lin ◽

◽

Branko Bijeljic ◽

Samuel C. Krevor ◽

Martin J. Blunt ◽

...

Keyword(s):

Multiphase Flow ◽

Wettability Alteration ◽

Pore Scale ◽

Flow Experiments

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Development and Validation of a Three-Dimensional Multiphase Flow CFD Analysis for Journal Bearings in Steam and Heavy Duty Gas Turbines

Volume 7: Structures and Dynamics, Parts A and B ◽

10.1115/gt2012-68201 ◽

2012 ◽

Cited By ~ 2

Author(s):

Stephan Uhkoetter ◽

Stefan aus der Wiesche ◽

Michael Kursch ◽

Christian Beck

Keyword(s):

Experimental Data ◽

Multiphase Flow ◽

Gas Turbines ◽

High Speed ◽

Three Dimensional ◽

Air Entrainment ◽

Journal Bearings ◽

Heavy Duty ◽

Present Contribution ◽

Two Phase

The traditional method for hydrodynamic journal bearing analysis usually applies the lubrication theory based on the Reynolds equation and suitable empirical modifications to cover turbulence, heat transfer, and cavitation. In cases of complex bearing geometries for steam and heavy-duty gas turbines this approach has its obvious restrictions in regard to detail flow recirculation, mixing, mass balance, and filling level phenomena. These limitations could be circumvented by applying a computational fluid dynamics (CFD) approach resting closer to the fundamental physical laws. The present contribution reports about the state of the art of such a fully three-dimensional multiphase-flow CFD approach including cavitation and air entrainment for high-speed turbo-machinery journal bearings. It has been developed and validated using experimental data. Due to the high ambient shear rates in bearings, the multiphase-flow model for journal bearings requires substantial modifications in comparison to common two-phase flow simulations. Based on experimental data, it is found, that particular cavitation phenomena are essential for the understanding of steam and heavy-duty type gas turbine journal bearings.

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