Fluids In Porous Media Research Articles

Transport Modelling of Multi-Phase Fluid Flow in Porous Media for Enhanced Oil Recovery

This article studies the combined effect of spatial heterogeneity and capillary pressure on the saturation of two fluids during the injection of immiscible nanoparticles. Various literature review exhibited that the nanoparticles are helpful in enhancing the oil recovery by varying several mechanisms, like wettability alteration, interfacial tension, disjoining pressure and mobility control. Multiphase modelling of fluids in porous media comprise balance equation formulation, and constitutive relations for both interphase mass transfer and pressure saturation curves. A classical equation of advection-dispersion is normally used to simulate the fluid flow in porous media, but this equation is unable to simulate nanoparticles flow due to the adsorption effect which happens. Several modifications on computational fluid dynamics (CFD) have been made to increase the number of unknown variables. The simulation results indicated the successful transportation of nanoparticles in two phase fluid flow in porous medium which helps in decreasing the wettability of rocks and hence increasing the oil recovery. The saturation, permeability and capillary pressure curves show that the wettability of the rocks increases with the increasing saturation of wetting phase (brine).

Numerical investigation on abnormally elevated pressure in laboratory-scale porous media caused by depressurized hydrate dissociation

Hydrate dissociation induced by artificial or environmental factors in submarine sediments may lead to drilling risks, submarine landslides, and the collapse of offshore platforms—all of which are associated with suddenly increased pore pressure. This study establishes a coupled model for the two-phase flow of fluids in porous media in which the pore pressure of water and gas are used as dependent variables and heat transfer and hydrate dissociation equations are combined. The simulation results of the model are consistent with Masuda’s experimental dataset. A quantifiable controlling hydrate dissociation specific reaction surface area (SRSA) model and an absolute permeability model are proposed to conduct numerical simulations of laboratory-scale hydrate cores, with the aim to investigate the mechanism of hydrate dissociation-induced geological hazard initiation and a law of their evolution in sediments. The results show that i) suddenly depressurized hydrate dissociation in porous media can be divided into three phases—pressure induction, transition, and temperature-controlled—and that the first two are much shorter than the third. Moreover, the lower initial permeability results in a shorter holding period for the first stage, and the transition phase becomes indistinguishable; conversely, the larger initial permeability makes the three stages more distinguishable; ii) hardly increasing the core permeability during the intermediate stage of hydrate dissociation makes the pore pressure rebound. However, the steep increase in SRSA does not result in a significant pore gas pressure rebound; conversely, a larger SRSA does facilitate pore pressure dissipation. This work provides theoretical and laboratory-scale model analyses for the safe development of natural gas hydrates bearing in marine sediments.

Studying the influence of capillary phenomena in two-phase filtration of immiscible fluids in porous media

The article deal with a new approach to the assessment of geological and technological efficiency of the implementation of the remedial cementing (a case study of water shut-off treatment) in the productive part of Vikulov suite in order to limit the level of water inflow into the near-well area of the array and maximize the duration of waterless period of crude oil production in the conditions of two-phase filtration.

Comparison between direct numerical simulations and effective models for fluid-porous flows using penalization

This work is devoted to a numerical study of two-dimensional incompressible flows in a fluid-porous medium system placed on an impermeable wall. Flow in the whole system is studied either at the pore scale or at the Darcy scale (using a one-domain approach) and the models at both scales are solved with a penalization method using the same formal Navier–Stokes equations modified by a Darcy-like term. Several effective medium penalized models are considered for the simulations. Various flow regimes are investigated ranging from laminar to turbulent. The velocity profiles inside and outside the porous medium show significant discrepancies between the different penalization models compared to the direct numerical simulations. This work motivates further studies about the spatial variations of the penalization coefficient to be introduced in the effective medium models in order to better reproduce the physics near the fluid-porous medium boundaries.

Characterization investigation on pore-resistance relationship of oil contaminants in soil porous structure

The leaked contaminants from buried oil pipelines have a great potential to damage the ecological environment. It is significant to accurately and effectively predict the migration destination and diffusion range of oil contaminants in soil, which can keep contaminants to a minimum, and also can help to formulate the environmental impact assessment and remediation plan. In this paper, the Quartet Structure Generation Set algorithm (QSGS) is adopted to reconstruct the soil porous structure, and the binary image segmentation method is introduced to evaluate the algorithm quantitatively. The D2Q9 scheme of Lattice Boltzmann Method (LBM) is employed to simulate the mesoscopic scale migration of oil contaminants in soil. The influence of different porosities on the velocity field, pressure field and streamline distribution of oil contaminants in the computational domain is analyzed. Based on the measurement experiment of resistance coefficient in porous medium, the linear relationship between the square root of pressure difference Δp0.5 and the percolation velocity v is obtained under four conditions. The migration resistance coefficient κR is introduced to characterize the migration ability of fluid in porous medium. When the contaminants type and permeation path length of fluid in porous medium are fixed, the migration resistance coefficient κR decreases with the increase of soil porosity, which can be described with a quadratic polynomial function. Thus, it is essential to investigate of pore-resistance relationship for the mesoscopic migration of oil contaminants in soil.

Biomimetic porous polypropylene foams with special wettability properties

Nowadays, the subject of wettability still has received little attention in the scientific literature, especially in the cellular solids, despite its significant role in the pervasiveness of the water treatment. Herein, inspired by the mussel, a green method was developed to construct nano-/micro-structures on the multi-structural polypropylene (like the dense solids, big hollow, small hollow and hierarchical open/closed-cell porous structure) by the surface-adherent polydopamine. Moreover, the relationship between both surface chemical and physical (such as pore structure and size) properties of the porous media, and wettability were studied. Besides, water–glycerol mixture solutions with various viscosities were used to study the spreading and imbibition behavior in the porous polypropylene foams, and the surface free energy of the different cellular solids (before and after modification) was estimated by Owens-Wendt equation. More interestingly, different kinds of the super-wetting materials like super-amphiphilic and hierarchical super-hydrophilic/super-hydrophobic, etc., were successful prepared. Both fundamental theoretical and numerical analysis were also conducted to reveal the mechanism of the penetration or surface repellency toward a drop, and to predict the transport of fluids in porous media. We believe that this work may serve as a source of inspiration in designing other advanced functional materials.

Investigation of the resonance of nonwetting droplets in constricted capillary tubes

Fluids in porous media could resonate due to passing seismic waves when meeting certain conditions of excitation frequency and pore geometry. This study of the resonance of fluids can contribute to applications in hydrocarbon microtremor analysis, enhanced oil recovery methods, and environmental remediation of nonaqueous phase liquid contamination. In this study, the analytical expression of the frequency response function and temporal response function is derived to characterize the resonance of two-phase immiscible fluids in the constricted tube. The computational fluid dynamics modeling is used to validate this resonance theory by achieving a good agreement in the prediction of output/input amplification ratio in the frequency and time domains.

Combination of MRI and SEM to Assess Changes in the Chemical Properties and Permeability of Porous Media due to Barite Precipitation

The understanding of the dissolution and precipitation of minerals and its impact on the transport of fluids in porous media is essential for various subsurface applications, including shale gas production using hydraulic fracturing (“fracking”), CO2 sequestration, or geothermal energy extraction. In this work, we conducted a flow through column experiment to investigate the effect of barite precipitation following the dissolution of celestine and consequential permeability changes. These processes were assessed by a combination of 3D non-invasive magnetic resonance imaging, scanning electron microscopy, and conventional permeability measurements. The formation of barite overgrowths on the surface of celestine manifested in a reduced transverse relaxation time due to its higher magnetic susceptibility compared to the original celestine. Two empirical nuclear magnetic resonance (NMR) porosity–permeability relations could successfully predict the observed changes in permeability by the change in the transverse relaxation times and porosity. Based on the observation that the advancement of the reaction front follows the square root of time, and micro-continuum reactive transport modelling of the solid/fluid interface, it can be inferred that the mineral overgrowth is porous and allows the diffusion of solutes, thus affecting the mineral reactivity in the system. Our current investigation indicates that the porosity of the newly formed precipitate and consequently its diffusion properties depend on the supersaturation in solution that prevails during precipitation.

Quantitative Characterization of Foam Transient Structure in Porous Media and Analysis of Its Flow Behavior Based on Fractal Theory

Foam fluid is widely used in petroleum industry, so the behavior of foam fluid flow in porous media directly affects the application effect of foam. However, the foam flow pattern in porous media is difficult to established because of its dynamic change of interface structure and unpredictable boundary condition. In this work, the transient structural changes of foam fluid in porous media are quantitatively characterized, and the flow behavior is analyzed based on fractal theory and visual experiments. Firstly, the foam fractal characteristics are verified and the fractal dimension is calculated. Results shows that the foam fractal dimension is between 1.5~2.0, and the foam flow can be divided into three stages: gas-liquid two-phase flow, foam unstable flow stage and foam stable flow stage. In addition, the evaluation indexes of foam performance in porous media are proposed to evaluate the influencing factors. Namely, the fractal dimension in stable stage Dfoam-s and the time needed to reach stability Ts....

Qualification of New Methods for Measuring In Situ Rheology of Non-Newtonian Fluids in Porous Media.

Pressure drop (ΔP) versus volumetric injection rate (Q) data from linear core floods have typically been used to measure in situ rheology of non-Newtonian fluids in porous media. However, linear flow is characterized by steady-state conditions, in contrast to radial flow where both pressure and shear-forces have non-linear gradients. In this paper, we qualify recently developed methods for measuring in situ rheology in radial flow experiments, and then quantitatively investigate the robustness of these methods against pressure measurement error. Application of the new methods to experimental data also enabled accurate investigation of memory and rate effects during polymer flow through porous media. A radial polymer flow experiment using partially hydrolyzed polyacrylamide (HPAM) was performed on a Bentheimer sandstone disc where pressure ports distributed between a central injector and the perimeter production line enabled a detailed analysis of pressure variation with radial distance. It has been suggested that the observed shear-thinning behavior of HPAM solutions at low flux in porous media could be an experimental artifact due to the use of insufficiently accurate pressure transducers. Consequently, a generic simulation study was conducted where the level of pressure measurement error on in situ polymer rheology was quantitatively investigated. Results clearly demonstrate the robustness of the history match methods to pressure measurement error typical for radial flow experiments, where negligible deviations from the reference rheology was observed. It was not until the error level was increased to five-fold of typical conditions that significant deviation from the reference rheology emerged. Based on results from pore network modelling, Chauveteau (1981) demonstrated that polymer flow in porous media may at some rate be influenced by the prior history. In this paper, polymer memory effects could be evaluated at the Darcy scale by history matching the pressure drop between individual pressure ports and the producer as a function of injection rate (conventional method). Since the number of successive contraction events increases with radial distance, the polymer has a different pre-history at the various pressure ports. Rheology curves obtained from history matching the radial flow experiment were overlapping, which shows that there is no influence of geometry on in-situ rheology for the particular HPAM polymer investigated. In addition, the onset of shear-thickening was independent of volumetric injection rate in radial flow.

Partial Differential Equation-Based Trajectory Planning for Multiple Unmanned Air Vehicles in Dynamic and Uncertain Environments

Abstract This paper proposes a physics-inspired method for unmanned aerial vehicle (UAV) trajectory planning in three dimensions using partial differential equations (PDEs) for application in dynamic hostile environments. The proposed method exploits the dynamical property of fluid flowing through a porous medium. This method evaluates risk to generate porosity values throughout the computational domain. The trajectory that encounters the highest porosity values determines the trajectory from the point of origin to the goal position. The best trajectory is found using the reaction of the fluid in porous media by the way of streamlines obtained by numerically solving the PDEs representing the fluid flow. Constraints due to UAV dynamics, obstacles, and predefined way points are applied to the problem after solving for the best trajectory to find the optimal and feasible trajectory. This method shows near-optimality and much reduced computational effort when compared to the other typical numerical optimization methods.

Leakage, heat transfer and thermal deformation analysis method for contacting finger seals based on coupled porous media and real structure models

Finger seal is a type of compliant seal configuration that has superior sealing performance compared with conventional labyrinth seals and brush seals. However, complex working conditions lead to leakage, thermal gradient and deformation, which can be more serious for a contacting finger seal due to frictional heating. In this paper, a leakage and thermal performance analysis method coupled with porous media and a real structure model was developed to numerically simulate the leakage, heat transfer and thermal deformation characteristics of a contacting finger seal. The method innovatively established a porous media fluid dynamics and heat transfer model and modified the frictional heating model by introducing the concept of a friction work conversion ratio. Then, the thermal deformation of the fingers was calculated on the basis of pressure and temperature results by using the thermal-stress module of ANSYS Workbench. The results show that the leakage analysis porous media model has good calculation accuracy and most of the fluid leaks through the finger foot, while the pressure drops mainly in this field. The highest finger temperature occurs at the downstream side of the contact surface between the finger foot and the rotor. The largest thermal deformation of each laminate occurs at the finger foot toe and increases slightly along the flow direction. Additionally, the largest relative circumferential thermal deformation can reduce the gap between the fingers by approximately 5%, which is beneficial for reducing leakage. It is suggested to increase the seal inner diameter at the finger foot toe but decrease it at the finger foot heel during the design process to decrease wear and leakage.

Effective Rheology of Bi-viscous Non-newtonian Fluids in Porous Media

We model the flow of a bi-viscous non-Newtonian fluid in a porous medium by a square lattice where the links obey a piece-wise linear constitutive equation. We find numerically that the flow regime where the network transitions from all links behaving according to the first linear part of the constitutive equation to all links behaving according to the second linear part of the constitutive equation, is characterized by a critical point. We measure two critical exponents associated with this critical point, one of the being the correlation length exponent. We find that both critical exponents depend on the parameters of the model.

Numerical analysis of a steady flow in a non-uniform capillary

Fluids in porous media driven by the capillary force are greatly affected by capillary?s geometrical structure. The steady flow in a non-uniform capillary is numerically analyzed by the finite element method. With the given initial and boundary conditions, the flow velocity distribution with different geometrical parameters is obtained, and the result is in a good agreement with the experimental data.

New insight into the Fourier-like and Darcy-like models in porous medium

In this study, we propose the general calculus operators based on the Richardson scaling law and Korcak scaling law. The Richardson-scaling-law calculus is considered to investigate the Fourier-like law for the scaling-law flow of the heat in the heat-transfer process. The Korcak-scaling-law calculus is used to model the Darcy-like law for describing the scaling-law flow of the fluid in porous medium. The formulas are as the special cases of the topology calculus proposed for descriptions of the fractal scaling-law behaviors in nature phenomena.

Thermal Impulse Response in Porous Media for Transpiration-Cooling Systems

A solution of the coupled differential equations for fluid and solid phases in a one-dimensional porous medium in thermal nonequilibrium is presented using the concept of analyzing the impulse response. The impulse response is shown to be sensitive to the volumetric heat transfer coefficient and the coolant mass flux. Experimental data obtained from surface heating of transpiration-cooled porous zirconium di-boride () samples are compared to a newly developed theoretical model. The surface and backside temperatures of the solid are measured using thermographic imaging and thermocouple instrumentation. The noninteger system identification approach is used to experimentally obtain the thermal impulse response, which is then compared to the model prediction. Good agreement is found between the simulated and experimental data with average deviations below 10%. The developed model provides the basis for inverse heat transfer measurements and further analysis of transpiration-cooled materials.

English

English

GPU-based Real-time Porous Medium Dynamic Network Simulation

Porous medium network simulation is to accurately describe the seepage law of multiphase fluids in porous media. Researchers have studied the relationship between various macroscopic physical properties of multiphase fluids (e.g. relative permeability, capillary pressure and fluid saturation) from theoretical, experimental, and computer simulation. This research introduces the construction method of stochastic pore network model and describes the calculation steps of pore network pressure field. In this research, the computational efficiency of the GPU-based pore network was compared with CPU. The calculation speed and simulation model scale of the pressure domain of the random pore network were improved.

A general peridynamics model for multiphase transport of non-Newtonian compressible fluids in porous media

A general state-based peridynamics model is developed to simulate transport of fluids in an arbitrary heterogeneous porous medium. The generality encompasses modeling of multiphase, multi-component flow of non-Newtonian and compressible fluids, which is often encountered in but not limited to subsurface reservoirs. Peridynamic model is especially useful for solving non-local problems, such as crack propagation, since it does not assume spatial continuity of field variables. Thus, the formulation presented here, combined with peridynamics-based damage model, can be used to simulate hydraulic fracturing with complex fluids. To demonstrate its capability to simulate multi-phase flow in porous media, the derived model is verified against the analytical Buckley-Leverett solution for immiscible Newtonian two-phase flow. Further, the non-Newtonian two-phase fluid flow in porous media is verified by simulating the polymer flood process involving immiscible displacement of a Newtonian fluid by a non-Newtonian fluid against a generalized solution obtained by Wu et al. [22]. The non-local solutions are shown to be consistent with the corresponding local solutions in limiting cases. Moreover, mass conservation of all the phases is satisfied, irrespective of discretization and extent of non-locality.

Mathematical Simulation of local transfer for non-Newtonian uid in porous fabrics

Many processes in the polymer composite, textile, food, and pharmaceutical industries are associated with the flow of non-Newtonian fluids in porous media. This paper considers the mathematical model of a multi-scale process for the filtration of non-Newtonian fluid in periodic porous fabrics. The model should be based on a three-dimensional Navier-Stokes equation with non-Newtonian Carreau-Yasuda viscosity using the asymptotic averaging method. A numerical algorithm was developed for solving local problems of non-Newtonian fluids in periodic cells, and the distribution of velocity, pressure and non-Newtonian viscosity in a single pore was obtained. The algorithm for calculating the permeability tensor is developed, and the effects of fluid rheology are also highlighted.