High Permeability Porous Media Research Articles

Impact of Polymer Rheology on Gel Treatment Performance of Horizontal Wells with Severe Channeling

Summary Gel treatment has been a cost-effective method to control the conformance of a reservoir with severe heterogeneity problems. The water channels in such reservoirs can be classified as open fractures or high permeability porous media with pore-throat network. Many simulation studies have been conducted to discuss gel treatment performance for conformance control. However, nobody considered the polymer rheology difference in open fractures and porous media in simulation. Previous simulation studies also ignored the residual resistance factor as a function of rock permeability rather than a constant parameter. In this study, a conceptual simulation model was established to simulate the linear flow system for the reservoir with horizontal wells considering the two factors mentioned above. The results demonstrate that the gel treatment always provides the better placement results in the open fracture type channel than pore-throat network type channel. Moreover, it is very necessary to consider residual resistance factor as a function of permeability, which is based on the experimental results and can provide much greater plugging efficiency in the higher permeable channels than constant residual resistance factor. Sensitivity analysis studies and multifactor analysis indicate that increasing oil viscosity and permeability ratio has a strong positive influence on conformance control results, which indicate in-situ gel treatment can be better applied in heavy or viscous oil reservoirs with fracture-like channels. Besides, the results also indicate that in reservoirs with severe channeling problem where channel velocity was high, the differences of gelant placement and profile improvement in models with two different types of channels could be enlarged greatly.

Coarsening reduction strategies to stabilize CO2-foam formed with a zwitterionic surfactant in porous media

Micromodel experiments at high-pressure high-temperature conditions were performed to evaluate the impact of different coarsening reduction strategies on CO2-foams stabilized with a zwitterionic surfactant, using silica nanoparticles in small concentration and mixing CO2 with a less water-soluble gas (nitrogen). The CO2-foam stabilized only by the surfactant showed poor behavior in the porous media, while an improvement in both foam texture (bubble density at the inlet of the micromodel) and gas trapping was qualitatively seen in the experiments using a nanofluid containing silica nanoparticles. The strong adsorption of the nanoparticles at the gas-water interface allowed to reduce the coarsening mechanism, reaching a minimum pressure gradient for strong foam generation throughout the micromodel chip. The use of a small concentration of nanoparticles in combination with the zwitterionic surfactant proved to be effective in reducing gas mobility without significant increase in pressure drop, which could be used as a strategy to control the mobility of injected CO2 in high permeability porous media, with reduced loss of injectivity. Coarsening was also reduced by using a mixture of CO2 and N2 as foaming gas, with an even greater gas mobility reduction, achieving a pressure drop 7.6 times higher compared to the CO2-foam stabilized only by surfactant. Furthermore, larger areas with trapped gas were visualized along the micromodel when co-injecting the mixture of gases and the zwitterionic surfactant solution. The large decrease in gas mobility seen for this strategy suggests that using a gas mixture would be suitable to control gas mobility in high-permeability channels and to block thief zones. The combination of using a gas mixture and a nanofluid to decrease CO2-foam destruction in porous media yielded a slight reduction in gas mobility, similar to that obtained with CO2-foam in the presence of nanoparticles, for they had similar pressure-drop values at same injection flow rate. The results obtained in this work demonstrated the importance of interfacial phenomena for tuning of coarsening and coalescence mechanisms associated with CO2-foam stability to the desired pore-scale application.

The effects of in-situ emulsion formation and superficial velocity on foam performance in high-permeability porous media

Foam has been considered as a mobility control agent for Enhanced Oil Recovery (EOR) applications in heterogeneous and fractured reservoirs. Foam enhances sweep efficiency by enabling the injected gas to flow from high-permeability to low-permeability regions. The foam injection velocity is an essential factor affecting foam mobility control and flow behavior. Furthermore, the presence of remaining oil adversely impacts foam generation leading to a failure in governing mobility control. In this study, foam performance in establishing mobility control effect and favorable apparent viscosity was experimentally investigated under a range of total superficial velocities in the presence and absence of crude oil during foam propagation in high permeability sand packs representing a propped fracture network. In the absence of oil, a pronounced effect of total superficial velocity on the mobility control performance was observed at the transition foam quality regime. Co-injection of oil and foam led to noticeable foam destabilization, as expected. However, a further increase in oil fractional flow resulted in larger overall flow resistance. We found that the formation of in-situ surfactant/oil emulsion contributed to the high apparent viscosity exhibited at the steady-state condition. These findings suggest that the steady-state flow resistance established during foam flooding at high oil saturations should be interpreted as the mobility control effect resulting from emulsion formation rather than the development of strong foam.

Polymer Flooding in Heterogeneous Heavy Oil Reservoirs: Experimental and Simulation Studies.

Polymer flooding (PF) in heterogeneous heavy oil reservoirs is not only closely related to polymer degradation, but also to non-Newtonian flow. In this paper, both experimental and simulation methods are combined to investigate this type of flooding. Through experiments, the degradation of polymer, rheological properties of fluids, and flow of fluids in porous media were determined. Based on the experimental results, a novel mathematical model was established, and a new PF simulator was designed, validated, and further applied to study the effects of polymer degradation, polymer solution shear thinning, and non-Newtonian flow on PF in heterogeneous heavy oil reservoirs. These experimental results demonstrated that the polymer first-order static degradation rate constant was lower than the polymer first-order dynamic degradation rate constant; the polymer solution and heavy oil were non-Newtonian fluids, with shear thinning and Bingham fluid properties, respectively; and the heavy oil threshold pressure gradient (TPG) in low-permeability porous media was higher than that in high-permeability porous media. All comparison results showed that the designed simulator was highly accurate and reliable, and could well describe both polymer degradation and non-Newtonian flow, with special emphasis on the distinction between polymer static and dynamic degradation and heavy oil TPG. Furthermore, the simulation results verified that polymer degradation, polymer solution shear thinning, and heavy oil TPG all had negative effects on the efficiency of PF in heterogeneous heavy oil reservoirs.

Experimental and numerical upscaling of foam flow in highly permeable porous media

Foam in porous media has been studied as a tool for various applications. Recently, the technology has become relevant for contaminated-aquifer remediation, where porous media are highly permeable. Therefore, the behavior of foam flow in high permeability porous media still raises numerous questions. In particular, upscaling of the foam flow from pore to Darcy scale is still under debate. Since the behavior of bulk foam has been studied principally in the food and cosmetics industries, and foam flow in porous media has mainly been investigated in the oil industry, the link between bulk-foam behavior and foam flow in porous media is still missing. The upscaling of foam flow from the pore scale to the laboratory scale could give valuable insight for understanding foam flow in aquifers.We studied the behavior of pre-generated foam with different foam qualities through the rheological characterization of bulk foam using a rheometer and also when flowing in a porous medium composed of 1 mm glass beads. Foam was formed by co-injecting surfactant solution and nitrogen gas through a porous column filled by fine sand. The homogenization method is used to study macroscopic foam flow properties in porous media by solving the non-linear boundary value problem. The rheology of bulk foam is then used as an input in the upscaling procedure for foam flow in different periodic model 2D and 3D unit cells.From our experiments, we found that the bulk foam is a yield-stress fluid and that the yield-stress values increase with foam quality. Moreover, the rheology of bulk foam corresponds well to the yield stress (Herschel-Bulkley-Papanastasiou) model. We found that foam behaves as a continuous yield-stress fluid in highly permeable porous media. It was also shown that the apparent foam viscosity in porous media increases with the foam quality at the same total flow rate. The results obtained from the rheometer successfully match the outcomes of apparent foam viscosity obtained by flow in porous media by a shifting parameter for the same foam quality. The apparent foam viscosity found in 1 mm glass-bead packing was much higher than bulk foam viscosity.Experimental results were compared to numerical results on simple unit cells. Although we observed considerable differences between the experimental and numerical results of upscaling, the general trend was identical. The differences can be explained by the complexity of the foam flow in porous media, especially foam compressibility. We found that foam flow at low capillary numbers is influenced by the trapping effect and at high pressure gradients by the compressibility. Compressibility was estimated for foam flow in 1 mm glass-bead packing. When foam compressibility is insignificant, the upscaling model can predict foam-flow behavior well at the Darcy scale.

Pore-Scale Investigation on the Plugging Behavior of Submicron-Sized Microspheres for Heterogeneous Porous Media with Higher Permeability

Reservoir heterogeneity is regarded as one of the main reasons leading to low oil recovery for both conventional and unconventional reservoirs. High-permeability layers or fractures could result in ineffective water or gas injection and generate nonuniform profile. Polymer microspheres have been widely applied for the conformance control to overcome the bypass of injected fluids and improve the sweep efficiency. For the purpose of examining the plugging performance of submicron-sized microspheres in high-permeability porous media, systematic investigations were implemented incorporating macroscale blocking rate tests using core samples and pore-scale water migration analysis via nuclear magnetic resonance (NMR). Experimental results indicate that microsphere particle size dominates the plugging performance among three studied factors and core permeability has the least influence on the plugging performance. Subsequently, microsphere flooding was conducted to investigate its oil recovery capability. Different oil recovery behaviors were observed for cores with different permeability. For cores with lower permeability, oil recovery increased stepwise with microsphere injection whereas for higher permeability cores oil recovery rapidly increased and reached a plateau. This experimental work provides a better understanding on the plugging behavior of microspheres and could be employed as a reference for screening and optimizing the microsphere flooding process for profile control in heterogeneous reservoirs.

Polymer flooding in high-temperature and high-salinity heterogeneous reservoir by using diutan gum

Diutan gum, a biopolymer that has been widely used in cement and concrete industries, was introduced in this work to alleviate severe viscosity loss and the poor water solubility of polyacrylamide and its modified products in high-temperature and high-salinity reservoirs. Diutan gum is an exopolysaccharide secreted by sphingomonas. The rheological properties and capacity of diutan gum to enhance oil recovery in high-temperature and high-salinity heterogeneous reservoir (T = 130 °C, Total salinity = 223.07 g L−1, Vk = 0.93) was investigated and compared with those of two other kinds of biopolymer thickeners (xanthan and konjac gum), which are commonly used in oilfield development. The three biopolymers show pseudoplastic fluid properties in a steady-state rheological test: given the strong interactions in the double-helix structure of diutan gum, the number of the Newtonian zone and the shear rate of this zone are higher than the those of the two other biopolymers. The storage modulus (G′) of diutan gum are higher than its loss modulus (G″) in all the concentrations and frequencies measured through viscoelasticity tests. This result indicates that diutan gum exhibits remarkable elasticity in slow displacement speed while it seeping in porous media. The capability of establish flow resistance in high-permeability porous medium in high-temperature and high-salinity environment by three biopolymers was studied, and their viscosity and microscopic properties of injected and produced fluid were investigated to understand the reason why diutan gum can have good fluidity control ability. Oil displacement efficiency can be improved by the elasticity of the diutan gum even without an increase in displacement speed. The results of the oil displacement experiments in the heterogeneity model imply that diutan gum is more effective in improving the water injection profile of each layer than xanthan and konjac gum. The water channeling in the high-permeability layer is restrained, and the sweep ability of the displacement phase is improved. Furthermore, the effect of polymer flooding can be maintained for a long time. Under high-temperature, high-salinity and strong heterogeneity, diutan gum recovers 19.34% of original oil in place (OOIP). This value is higher than the values obtained with xanthan gum (14.15% OOIP) and konjac gum (8.60% OOIP). This finding implies that the diutan gum has great application potential in the development of high-temperature and high-salinity reservoirs with strong heterogeneity.

COMPUTATION OF TRANSIENT RADIATIVE REACTIVE THERMOSOLUTAL MAGNETOHYDRODYNAMIC CONVECTION IN INCLINED MHD HALL GENERATOR FLOW WITH DISSIPATION AND CROSS DIFFUSION

The present article investigates the collective influence of chemical reaction, viscous dissipation and Hall current magnetic effects on timedependent radiative magnetohydrodynamic flow, heat and mass transfer from an inclined wall embedded in a homogenous, isotropic highpermeability porous medium. The model developed is relevant to near wall magnetohydrodynamic energy generator transport phenomena in which chemical corrosion effects may arise during operations. The governing non-linear partial differential equations for mass, momentum, energy and species conservation are transformed into a system of coupled non-linear dimensionless partial differential equations with appropriate similarity variables. The normalized conservation equations are then solved with a robust finite element method (MATLABFEM) subject to corresponding initial and boundary conditions. Important dimensionless parameters emerging are Eckert number, thermal Grashof number, solutal Grashof number, magnetic body force parameter, Hall parameter, permeability parameter, Dufour number, Soret number, time, radiation-conduction parameter, chemical reaction parameter, heat absorption parameter, Prandtl number, Schmidt number and wall angle. Primary velocity is enhanced with Eckert number, thermal Grashof number, solutal Grashof number, Hall parameter, permeability parameter, Dufour number, Soret number, radiation-conduction parameter and time whereas it is reduced with first order chemical reaction parameter, heat absorption, magnetic body force parameter, Prandtl number, Schmidt number and wall inclination. Secondary velocity is elevated with Eckert number, solutal Grashof number, thermal Grashof number, magnetic body force parameter, Hall parameter, radiation-conduction parameter, Dufour number, Soret number and time whereas it is suppressed with reaction parameter, heat absorption, Prandtl number, Schmidt number and wall inclination. Temperature is enhanced with Eckert number, Dufour number, heat absorption, radiation-conduction parameter and time whereas it is depressed with Prandtl number. Species concentration is reduced with increasing chemical reaction parameter (destructive homogenous reaction) and Schmidt number whereas it is elevated with Soret number and time. Extensive discussion of the finite element formulation, convergence and validation is provided Skin friction, Nusselt number and Sherwood number distributions are also provided for selected parameter variation. Validation of solutions with published literature is also included for several special cases, namely non-reactive, non-dissipative flow in the absence of heat generation or absorption. Further validation is included using a multi-step differential transform method (MS-DTM). The present simulations provide an interesting insight into complex fluid/thermal/species diffusion characteristics in the boundary layer region of relevance to working MHD generator systems.

The role of flow rates on flow patterns and saturation in high-permeability porous media

This study aimed to investigate dynamic CO2 drainage using high-resolution magnetic resonance imaging (MRI) technology. Gaseous and supercritical CO2 were injected downward in brine-saturated porous media at different flow rates at 40 °C/6 MPa and 40 °C/8 MPa. These flow rates (0.015, 0.03 and 0.1 mL/min, under 10 Mt/year), as reflected in, were chosen according to the distance (1 km–100 m) from the injection well. Three stages were found from the change of signal intensity during CO2 drainage: before the CO2 front reached the field of view (FOV), breakthrough, and steady state. Channelling or drainage fronts immediately established through the large pores, and CO2 travelled vertically through these channels until breakthrough. The breakthrough time decreased with increasing flow rates and was longer for ScCO2 than gCO2 at the same flow rate, resulting in a longer residence time for ScCO2 in the sample. At low flow rates, the fingers first established along the larger pore spaces (especially at 0.015 mL/min) and then gradually extended into adjacent regions, resulting in a relatively flat interface. However, at high flow rates, the front moved along the larger pore spaces until breakthrough. The flow patterns for ScCO2 drainage were more uniform than those for gCO2 drainage. The pore volume fraction occupied by CO2, as a quantitative parameter of the flow pattern, reflected that the sweep efficiency and pore space utilization were optimized at 0.03 mL/min (Ca = 4.35 × 10−9 for gCO2 and Ca = 1.06 × 10-8 for ScCO2). The effect of the flow rate on the CO2 saturation and distribution was analysed. At low flow rates, the saturation gradient along the porous media gradually reduced, but trend to be stable at high flow rates. Additionally, the saturation at breakthrough and steady state were observed to be linearly related to the maximum rate of change in saturation during CO2 injection. Overly fast drainage results in relatively low saturation and an inhomogeneous distribution. The results can be applied to provide information for enhancing pore space utilization and improving sweep efficiencies during field storage.

Numerical investigation on laminar slot-jet impinging on a surface at uniform heat flux in a channel partially filled with a porous medium

Jet impingement of a cold fluid is an efficient cooling method of a heated surface. Jets employed together with porous media with high porosity and thermal conductibility, such as aluminum foams, allows to improve the heat removal from a heated surface. In the present study, a parallel-plate channel filled partially with a high permeability porous medium and a single slot jet impinging on the porous medium is investigated numerically. The opposite wall to the air slot jet is partially heated at uniform heat flux. The porous medium is modeled using the Brinkman–Forchheimer-extended Darcy model that takes into account viscosity and inertia effects. The analysis in the porous medium is accomplished under local thermal equilibrium conditions and a two-dimensional numerical model is developed to evaluate the hydrodynamic and heat transfer characteristics within the channel. The investigations are carried out for 1<Pe<1000 and 10<Ra*<1000 at several thickness of the porous medium. Results indicate that for the channel with a porous medium thickness equal to the channel gap the highest average Nusselt number are detected.

Finite element computation of transient dissipative double diffusive magneto-convective nanofluid flow from a rotating vertical porous surface in porous media

This article aimed to investigate the transient dissipative magnetohydrodynamic double diffusive free convective boundary layer flow of electrically conducting nanofluids from a stationary or moving vertical porous surface in a rotating high permeability porous medium, considering buoyancy, thermal radiation and first-order chemical reaction. Thermo-diffusion (Soret) and diffuso-thermo (Dufour) effects are also considered. Darcy’s law is employed. The mathematical model is formulated by considering water-based nanofluids containing metallic nano-particles for both stationary and moving plate cases. Three nanofluids are examined, namely copper, aluminium oxide or titanium oxide in water. The transformed non-linear, coupled, dimensionless partial differential equations describing the flow are solved with physically appropriate boundary conditions using Galerkin weighted residual scheme. For prescribed permeability, numerical results are presented graphically for the influence of a number of emerging parameters. Validation of finite element solutions for skin friction and Nusselt number is achieved via comparison with the previously published work as special cases of the present investigation and very good correlation obtained. Increasing rotational parameter is observed to reduce both primary and secondary velocity components. Primary and secondary velocities are consistently elevated with increasing Soret, Dufour, thermal Grashof and solutal Grashof numbers. Increasing Schmidt number, chemical reaction and suction parameter both suppress nano-particle concentration whereas the converse behavior is computed with increasing Soret number. The study is relevant to high-temperature rotating chemical engineering systems exploiting magnetized nanofluids and also electromagnetic nanomaterial manufacturing processes.

Modeling of inertial multi-phase flows through high permeability porous media: Friction closure laws

During a severe accident in a nuclear reactor, the core may be fragmented in a debris bed made of millimetric particles. The main safety procedure consists in injecting water into the core leading to a steam-water flow through a hot porous medium. To assess the coolability of debris bed, there is a need for an accurate two-phase flow model including closure laws for the pressure drop. In this article, a new model for calculating pressure losses in two-phase, incompressible, Newtonian fluid flows through homogeneous porous media is proposed. It has been obtained following recent developments in theoretical averaging of momentum equations in porous media. The pressure drops in the momentum equations are determined by eight terms corresponding to the viscous and inertial friction in liquid and gas phases, and interfacial friction between the phases. Analytical correlations with the void fraction have been formulated for each term using an original experimental database containing measurements of pressure drops, average velocities and void fractions from the IRSN CALIDE experiment. The new model has then been validated against the experimental data for various liquid and gas Reynolds numbers up to several hundreds. Finally, it has been compared to the models, usually used in the “severe accident” codes, which are based on a generalization of the Ergun law for multi-phase flows. The results show that the new model gives a better prediction both for the pressure drop and for the void fraction.

Numerical Study of Nonlinear Heat Transfer from a Wavy Surface to a High Permeability Medium with Pseudo-Spectral and Smoothed Particle Methods

Motivated by petro-chemical geological systems, we consider the natural convection boundary layer flow from a vertical isothermal wavy surface adjacent to a saturated non-Darcian high permeability porous medium. High permeability is considered to represent geologically sparsely packed porous media. Both Darcian drag and Forchheimer inertial drag terms are included in the velocity boundary layer equation. A high permeability medium is considered. We employ a sinusoidal relation for the wavy surface. Using a set of transformations, the momentum and heat conservation equations are converted from an (x, y) coordinate system to an ( $$x, \eta )$$ dimensionless system. The two-point boundary value problem is then solved numerically with a pseudo-spectral method based on combining the Bellman–Kalaba quasi linearization method with the Chebyschev spectral collocation technique (SQLM). The SQLM computations are demonstrated to achieve excellent correlation with smoothed particle hydrodynamic (SPH) Lagrangian solutions. We study the effect of Darcy number (Da), Forchheimer number (Fs), amplitude wavelength (A) and Prandtl number (Pr) on the velocity and temperature distributions in the regime. Local Nusselt number is also computed for selected cases. The study finds important applications in petroleum engineering and also energy systems exploiting porous media and undulating (wavy) surface geometry. The SQLM algorithm is shown to be exceptionally robust and achieves fast convergence and excellent accuracy in nonlinear heat transfer simulations.

Dynamics of diffusive and convective transport in porous media: A fractal analysis of 3-D images obtained by laser technology

The objective of this paper was to use laser imaging technique to visualize the diffusion controlled mass transfer process in porous media. Cubical models made of different materials (oil-wet plexiglass and water wet glass) and filled with 1mm and 4mm glass beads and different types of oils were used to visualize the -Fickian- diffusion of solvent with different densities and viscosities. 3-D visualization technique with laser sheet scanning of refractive index matched glass-bead-pack model was used to study the effect of permeability, solvent density, viscosity and boundary effect on mixing by diffusion. Three types of solvents were used: (1) solvent with density higher than oil but low viscosity, (2) solvent lighter than oil but has high viscosity, and (3) solvent lighter but less viscous than oil.It was observed through 3-D images obtained from the experiments that the width (area) of the solvent swept region and fingering depended on the density of the solvent and the speed of the process was higher in the high permeability porous media (4mm glass beads). Wider fingers and swept areas were observed for less viscous solvent. Solvents 1 and 2 slowly mixed and rose to the top of the model filling most of the pores in the model, and then diffused into the unswept region. Solvent 3 reached the top of the model in an extremely short time along the boundary with thin fingering and displaces downward afterwards. The frontal progresses of solvent-oil interfaces (mixing zone) were analyzed quantitatively through the change of the fractal dimension during the process. The fractal dimension increased before the solvent reached at the top of the model. For solvents 1 and 2, the fractal dimension decreased afterward. For solvent 3, the value declined rapidly because the solvent took time to spread along the top of the model due to its extremely low viscosity and density.

Free and forced gas convection in highly permeable, dry porous media

The spatial and temporal distribution of gas species within the vadose zone is determined by biochemical sources and by transport mechanisms. Here, two mechanisms that can transfer gas at high rates across the earth-atmosphere interface are studied. The first is thermal convection venting (TCV), a free convection process that develops under conditions of sufficient temperature and density gradients. The second mechanism is wind-induced convection (WIC), an outcome of atmospheric surface winds that drive air movement within the porous media by a forced-convection process. Both of these advective mechanisms can dominate gas transport in high permeability porous media, and the objective of this study was to determine the permeability values that are relevant for these mechanisms to become significant for gas transport. Experiments were performed using large columns filled with four different single-sized spherical particles of 1 to 4cm in diameter. The experiments were conducted in a climate-controlled laboratory, where surface winds and temperature gradients were imposed and monitored. A tracer gas of CO2-enriched air was used to quantify the impact of TCV and WIC on gas exchange between the porous media and the atmosphere. A permeability range of 10−7 to 10−6m2 was found to be sufficient for the onset of TCV when imposed temperature gradients were similar to standard nighttime atmospheric conditions, leading to full or partial venting of the column. Surface wind with a velocity of 1.5ms−1 drove WIC to a depth of 0.3m in most experimental conditions. The impact of WIC on net gas transport was not observed at the bottom-most sensor (0.9m), except under conditions of very high permeability (2.4 10−6m2) and a large temperature difference (6.5°Cm−1), when both TCV and WIC worked simultaneously. Results confirm that TCV and WIC can significantly contribute to gas transport through porous media with sufficiently high permeability.

Spectral quasilinear numerical simulation of micropolar convective wall plumes in high permeability porous media

Laminar natural convection plume of a microstructural non-Newtonian fluid along a vertical surface about a line heat source in a saturated high permeability porous medium is studied. The transformed non-linear boundary value problem is solved numerically using a rigorously tested SQLM algorithm, which combines a spectral collocationmethod with the quasilinearization method (QLM). The effects of Grashof number, Prandtl number, Darcy number and Eringen micropolar rheological material parameters are examined. Excellent stability and convergence of the spectral method is demonstrated. Validation of solutions with the Keller box finite difference is included. Applications of the study arise in geological (petroleum) fluid dynamics.

Effect of Degree of Branching on the Mechanism of Hyperbranched Polymer To Establish the Residual Resistance Factor in High-Permeability Porous Media

To improve a polymer’s oil recovery power, it is imperative to discuss its residual resistance factor (RRF), which is a significant parameter in the field and is associated with the polymer molecular structure. This study investigated the capability of three kinds of hyperbranched polymers (HPDAs) with various degrees of branching to establish the RRF in high permeability porous media by way of a one-dimensional sandpack model under different polymer solution concentrations, permeabilities, and injection rates. In addition, the mechanisms of these polymers to establish the RRF were surveyed through altering the wettability of the rock surface. Furthermore, the diameter distribution and microstructure of the injected and produced polymer solution were determined by utilizing dynamic light scattering and scanning electron microscopy, respectively. The experimental results showed that the RRFs of three kinds of hyperbranched polymers were different in variation trend with changes in external conditions. As t...

Numerical investigation on laminar slot-jet impinging in a confined porous medium in local thermal non-equilibrium

A numerical investigation on a single slot jet impinging in a porous parallel-plate channel containing an air-saturated, high permeability porous medium is accomplished. The wall opposite the slot jet is partially heated at uniform heat flux and the buoyancy effects are taken into account. The fluid flow is assumed two dimensional, laminar and steady.The porous medium is modeled using the Brinkman–Forchheimer-extended Darcy model and the Boussinesq approximation. The local thermal non-equilibrium (LTNE) hypothesis is invoked. The results are discussed in terms of streamlines, fluid and solid phase temperature fields, wall temperature profiles and local and average Nusselt numbers.The porous medium allows a more significant heat transfer close to the end of the heated part of the plate. For low Peclet numbers, forced flow and natural convection are opposite and the mean Nusselt number shows a decrease in heat transfer, whereas they are aiding for high Peclet numbers. Porosity effects on the average Nusselt numbers were found weak.

The study on permeability reduction performance of a hyperbranched polymer in high permeability porous medium

This paper was focused on the permeability reduction performance of a hyperbranched polymer in high permeability porous medium. Water solubility, rheological property, viscoelasticity, and filtration experiments were adopted for investigating the solubility and injectivity of the hyperbranched polymer. Atomic force microscope (AFM), scanning electron microscope (SEM), and shear experiments were conducted for studying the microscopic structure, adsorption behavior, and shear resistance, respectively. Besides, resistance factor (RF), residual resistance factor (RRF), and displacement experiments were adopted for investigating the permeability reduction performance and enhanced oil recovery (EOR) ability of the hyperbranched polymer. It was found that the hyperbranched polymer exhibited acceptable water solubility, remarkable shear resistance, perfect permeability reduction and EOR ability. It was also found that the hyperbranched polymer owned higher apparent viscosity, viscosity retention rate, and adsorption retention due to the special network structure of polymer molecular chain.

Experimental and Numerical Investigation of CO&lt;sub&gt;2&lt;/sub&gt; Injection into Water-Saturated Porous Media: Effect of Capillary Pressure on Displacement Efficiency

CO2 sequestration in deep saline aquifers is regard as the most promising option among all the CO2 storage technologies. Capillary pressure can influence the CO2 storage efficiency in the aquifers. The core-scale experimental and numerical simulation studies are usually used to understand the mechanism and degree of such influence. Based on both magnetic resonance imaging (MRI) technique and numerical simulation method, this study investigates the effect of capillary pressure on the CO2 displacement efficiency in water-saturated porous media especially in quantitative form. Our results indicate: (1) the magnitude of capillary pressure may significantly affect the CO2-water displacement efficiency, and the displacement efficiency declines with increasing capillary pressure; (2) Sensitivity of the numerical model to capillary pressure becomes more unobvious with increasing capillary pressure. Thus, an accurate capillary pressure parameter is particularly required for improving the reliability of the model predictions in the case of the high permeability porous media.