Deposition In Porous Media Research Articles

Permeability Impairment Study Due to Asphaltene Deposition: Experimental and Modeling Approach

This fact is well known that during any scenario of production, asphaltene deposition in porous media has a substantial effect on oil flow. But a clear understanding of asphaltene deposition mechanisms can help to minimize asphaltenic problem in oil-bearing formations. In this study, the experimental results of three dynamic CO2 miscible injection tests were investigated. Regarding the effects of adsorption, mechanical entrapment, and sweeping mechanisms on permeability behavior, a mathematical mass and permeability variation model were developed. According to the experimental results asphaltene deposition causes a 70% loss of sand stone initial permeability while the loss is significantly low in carbonate cores, about 30%. The model validation shows that the main particulate processes of Asphaltene deposition in sandstone cores are the cake forming and adsorption while in the case of carbonate cores, are the gradual pore blocking and pore sweeping. Obtained results from mass model provide that entrainment and deposition coefficients in square mass model lead to a more flexible trend than the linear variation of general model.

Experimental, modelling and optimisation of asphaltene deposition and adsorption in porous media

AbstractThe deposition of asphaltene is considered to be one of the most difficult problems during oil production. Asphaltene deposition in the reservoir is a complex problem; and, due to the depth of reservoirs, it is impossible to do field experiments. Thus, to study the effects of asphaltene deposition, it is essential to rely on different models that are developed for asphaltene adsorption and deposition on the basis of the laboratory experimental results. In this manuscript, the focus is on the adsorption and deposition of asphaltene in porous media. A new model for asphaltene adsorption and deposition in porous media and a corresponding numerical method are developed using an implicit scheme. A procedure for estimating the asphaltene deposition and adsorption parameters is described, and a new optimisation method is introduced. This method applies the genetic algorithm to investigate an initial set of parameters as an input for the direct search optimisation method. The direct search estimates the asphaltene deposition and adsorption parameters, which results in an acceptable match with the experimental data. To validate the model, both the available experimental data in the literature and data from this study are examined with the developed model; and, reasonable results are obtained. © 2011 Canadian Society for Chemical Engineering

Modeling Formation Damage due to Asphaltene Deposition in the Porous Media

Asphaltene deposition in a reservoir severely reduces the effective permeability and results in a reduction in oil production. The main term in asphaltene deposition modeling in the porous media is pore surface deposition. Previous models do not describe the effects of different parameters (i.e., concentration, velocity, and temperature) on the pore surface deposition term. We report the results of a series of experiments carried out to study the effects of the above parameters on the surface deposition term using an accurate thermal method. Based on these data, a new expression for the surface deposition term has been developed and implemented in asphaltene deposition modeling. The developed model was used in simulating formation damage due to asphaltene deposition in porous media. The results are very promising and the calculated permeabilities are in very good agreement with the experimental data reported in the literature.

Predicting attachment efficiency of colloid deposition under unfavorable attachment conditions

This study presents an a priori model for predicting attachment efficiency of colloid deposition in porous media under unfavorable conditions. The model takes into account coupled effects of diffusion and hydrodynamic forces on colloid attachment efficiency that result from both primary and secondary minimum deposition. Effect of diffusion was quantified using the Maxwell approach, and influence of hydrodynamic drag was determined by comparing adhesive and hydrodynamic torques that act on the attached colloids. Main findings from this study include (1) the attachment efficiency does not change with increase of flow velocity until it reaches a critical value at which the attachment efficiency decreases as flow velocity further increases and (2) the attachment efficiency increases with increasing collector diameter when the condition that adhesive torque is greater than hydrodynamic torque is not guaranteed over the entire collector surface. Whereas the classic filtration theory only takes into account the effects of system hydrodynamics on single collector contact efficiency, we show additionally their effects on attachment efficiency. Furthermore, results of this study imply that in addition to the important role that collector size plays in the straining process, which has been the focus of many recent studies, it also influences the attachment process thus must be considered when describing colloid retention and transport in porous media under unfavorable attachment conditions.

A Novel Workflow to Model Permeability Impairment through Particle Movement and Deposition in Porous Media

This article presents a practical transfer function type solution to a complex problem in which variations in a number of parameters can be taken into account. A new mathematical model, which is based on mass balance transfer function of particles movement/retention in porous media, has been derived. It is used to predict permeability reduction as a function of time. The linear forms as well as the radial forms of the model are described. Although the differential equations derived are similar to the general form of diffusion–convection equations, the marked difference is the suitability of the model, for being applied for variation of parameters, such as particle concentration in the fluid, injection rate, density of solid particles, against the depth and time of invasion. This transfer function has been solved, and the results of the simulation run agree reasonably well with the experimental damage data obtained in laboratory. Owing to its simplicity, this model is more practical to describe permeability reduction for the flow of suspended particles in porous media.

Hemispheres-in-Cell Geometry to Predict Colloid Deposition in Porous Media

Hemispheres-in-Cell Geometry to Predict Colloid Deposition in Porous Media

Non-isothermal Permeability Impairment by Fines Migration and Deposition in Porous Media including Dispersive Transport

Particle migration and deposition, and resulting permeability impairment occurring in porous media are described by a practical phenomenological model considering temperature variation and particle transport by advection and dispersion. Variation of the filter coefficient and permeability of porous matrix by temperature and particle deposition, and other essential factors are considered by means of the special correlations of the relevant variables and dimensionless numbers. Comparison of the numerical results, obtained using a finite-difference numerical scheme with and without considering the dispersion mechanism and temperature variation, reveals the significance of such effects on fines migration and deposition, and consequent permeability impairment in porous media. Improved model presented in this article can be instrumental for scientifically guided experimentation, analysis, and optimal design of processes involving in transport of colloidal and fine particles through geological subsurface formations.

Contribution of Extracellular Polymeric Substances on Representative Gram Negative and Gram Positive Bacterial Deposition in Porous Media

The significance of extracellular polymeric substances (EPS) on cell transport and retained bacteria profiles in packed porous media (quartz sand) was examined by direct comparison of the overall deposition kinetics and retained profiles of untreated bacteria (with EPS) versus those of treated cells (without EPS) from the same cell type. Four representative cell types, Pseudomonas sp. QG6 (gram-negative, motile), mutant Escherichia coli BL21 (gram-negative, nonmotile), Bacillus subtilis (gram-positive, motile), and Rhodococcus sp. QL2 (gram-positive, nonmotile), were employed to systematically determine the influence of EPS on cell transport and deposition behavior. Packed column experiments were conducted for the untreated and treated cells in both NaCl (four ionic strength ranging from 2.5 mM to 20 mM) and CaCl(2) (5 mM) solutions at pH 6.0. The breakthrough plateaus of untreated bacteria were lower than those of treated bacteria for all four cell types under all examined conditions (in both NaCl and CaCl(2) solutions), indicating that the presence of EPS on cell surfaces enhanced cell deposition in porous media regardless of cell type and motility. Retained profiles of both untreated and treated cells for all four cell types deviated from classic filtration theory (log-linear decreases). However, the degree of deviation was greater for all four untreated cells, indicating that the presence of EPS on cell surfaces increased the deviation of retained profiles from classic filtration theory. Elution experiments demonstrated that neither untreated nor treated cells preferentially deposited in secondary energy minima. Furthermore, the release of previously deposited cells in the secondary energy minima did not change the shape of retained cell profiles, indicating that deposition in secondary energy minima did not produce the observed deviations of retained profiles from classic filtration theory.

Hemispheres-in-Cell Geometry to Predict Colloid Deposition in Porous Media

A "hemispheres-in-cell" geometry is provided for prediction of colloid retention during transport in porous media. This new geometry preserves the utilities provided in the Happel sphere-in-cell geometry; namely, the ability to predict deposition for a range of porosities, and representation of the influence of neighboring collectors on the fluid flow field. The new geometry, which includes grain to grain contact, is justified by the eventual goal of predicting colloid deposition in the presence of energy barriers, which has been shown in previous literature to involve deposition within grain to grain contacts for colloid:collector ratios greater than approximately 0.005. In order to serve as a platform for predicting deposition in the presence of energy barriers, the model must be shown capable of quantitatively predicting deposition in the absence of energy barriers, which is a requirement that was not met by previous grain to grain contact geometries. This paper describes development of the fluid flow field and particle trajectory simulations for the hemispheres-in-cell geometry in the absence of energy barriers, and demonstrates that the resulting simulations compare favorably to existing models and experiments. A correlation equation for predicting collector efficiencies in the hemispheres-in-cell model in the absence of energy barriers was developed via regression of numerical results to dimensionless parameters.

Experimental and Theoretical Study of Calcium Sulphate Precipitation in Porous Media Using Glass Micromodel

Mixing of two incompatible waters in water injection projects is usually associated with mineral scale formation and deposition in porous media. Deposition process dramatically affects the performance of water injection scenarios by reduction of porosity and mainly permeability of the rock. In this study, a series of experiments has been conducted to investigate the effect of different parameters on the gradual process of Calcium Sulphate precipitation. These include temperature, concentration of mixing brines, pressure, and flow rate. Due to the visual nature of the glass micromodel, a glass sandstone pattern with water-wet characteristics was used as porous medium to easily observe the scaling formation and distribution. In addition, tracing the movement of the solid particles is highly facilitated in this newly suggested experimental setup. The captured photos in microscopy scanning show that the deposition is initiated from the walls of the pores and throats and extend toward the middle space of porous medium and solid crystals look like chicken roost. For better understanding of the effect of any aforementioned parameter, the related permeability reduction curve versus injected pore volume of the brine solutions was plotted. The results indicated that as the temperature, brine concentration, and flow rate increase the scaling tendency increases as well. The pressure has a minor role on the process development. Deposition of CaSO4 manifests a functional form of permeability reduction due to the effect of different parameters. Therefore, an exponential functionality (correlation) was proposed which incorporates all physical parameters that affect the behavior of the system in dimensionless form. Reynolds number, scaling index, and deviation from equilibrium conditions are the backbone of this correlation. The adjustable exponents of the equation was determined and optimized by means of Genetic Algorithm optimization scheme. This meaningful correlation can also predict the core extracted data with reasonable accuracy.

Particle Size Distribution, Concentration, and Magnetic Attraction Affect Transport of Polymer-Modified Fe0 Nanoparticles in Sand Columns

The effect of particle concentration, size distribution (polydispersity) and magnetic attractive forces (Fe(0) content) on agglomeration and transport of poly(styrene sulfonate) (PSS) modified NZVI was studied in water-saturated sand (d(p) = 300 microm) columns. Particle concentrations ranged from 0.03 to 6 g/L in 5 mM NaCl/5 mM NaHCO3 at a pore water velocity of 3.2 x 10(-4) m/s. Three NZVI dispersions with different intrinsic particle size distributions obtained from sequential sedimentation are compared. The influence of magnetic attraction (Fe(0) content) on NZVI agglomeration and deposition in porous media is assessed by comparing the deposition behavior of PSS-modified NZVI (magnetic) having different Fe(0) contents with PSS-modified hematite (nonmagnetic) with the same surface modifier. At low particle concentration (30 mg/L) all particles were mobile in sand columns regardless of size or magnetic attractive forces. At high concentration (1 to 6 g/L), deposition of the relatively monodisperse dispersion containing PSS-modified NZVI (hydrodynamic radius (R(H)) = 24 nm) with the lowest Fe(0) content (4 wt%) is low (attachment efficiency (alpha) = 2.5 x 10(-3)), insensitive to particle concentration, and similar to PSS-modified hematite. At 1 to 6 g/L, the attachment efficiency of polydisperse dispersions containing both primary particles and sintered aggregates (R(H) from 15 to 260 nm) of PSS-modified NZVI with a range of Fe(0) content (10-60%) is greater (alpha = 1.2 x 10(-2) to 7.2 x 10(-2) and is sensitive to particle size distribution. The greater attachment for larger, more polydisperse Fe(0) nanoparticles with higher Fe(0) content is a result of their agglomeration during transport in porous media because the magnetic attractive force between particles increases with the sixth power of particle/agglomerate radius. A filtration model that considers agglomeration in porous media and subsequent deposition explains the observed transport of polydisperse PSS-modified NZVI at high concentration.

Asphaltene multilayer growth in porous medium probed by SANS

Presence of suspended particles such as asphaltene in crude oils could significantly affect the production by means of deposition in porous media especially near the well bore. We investigate this phenomenon using the ability of Small Angle Neutron Scattering technique to probe directly the asphaltene adsorption process in a porous medium at the nanometer length scale under flow conditions. A device based on a quartz tube filled with SiC particles constitute the porous medium in which an asphaltene solution in a mixture of good (toluene)/bad (heptane) solvent is injected under controlled flow. The contrast matching technique enables to match the porous medium scattering contributions and to measure the signal of the deposit. Such a device can be used for curves surface measurements on a setup originally designed for bulk studies and permit thus the direct comparison with measurements on flat surfaces (neutron reflectivity) and indirect adsorption measurements (adsorption isotherm). We show here that asphaltene in good solvent leads to a monolayer whereas addition of bad solvent results in a multilayer growth which is consistent with the deposition behaviour described in the literature.

Aggregation and transport of copper oxide nanoparticles in porous media

In this study, microscopic aggregates of copper oxide (CuO) nanoparticles were visualized in porous media for the first time. Two-dimensional microscopic visualization results showed that CuO aggregates formed in porous media regardless of flow velocity. The results demonstrated that flow velocity determined the density and location of aggregate deposition in porous media. The lower the flow velocity, the greater the number of aggregates deposited, and the larger the area of deposition-that is, it was not limited to the pore neck. Transport of CuO nanoparticles was also evaluated by comparing breakthrough curves at three different flow velocities. The higher the Darcy flow velocity, the more the CuO nanoparticles are discharged from the porous medium, and the less deposited they are within the medium. Surfactants significantly affected the fate and transport of CuO nanoparticles in porous media. Most of the CuO nanoparticles present in the surfactant solution flowed through the porous medium, while only 30% of the nanoparticles in water flowed through the medium. However, the results also demonstrated that some CuO aggregates did form, even in the presence of a surfactant.

Permeability reduction by asphaltenes and resins deposition in porous media

The deposition of crude oil polar fractions such as asphaltenes and resins in oil reservoir rocks reduce considerably the rock permeability and the oil production. In the present work, a crude oil and various core samples were extracted from Rhourd–Nouss (RN) reservoir rock. Afterwards, core flow experiments were carried out in the laboratory to investigate permeability reduction that causes formation damage. The core permeability damage was evaluated by flooding Soltrol, through the sample and measuring the solvent permeabilities, Ki and Kf, respectively, before and after injection of a given pore volume number of the crude oil.The data indicate that upon flooding the crude oil through the porous medium, considerable permeability reduction, expressed as the ratio (Ki−Kf)/Ki, and ranging from 72.4% to 98.3% were observed. The permeability reduction is found to result from irreversible retention of asphaltenes and resins in the porous core sample. However, no correlations could be established between the depth of the well, the core porosity, the core mineral compositions determined by X-ray analysis, and the permeability damage factors. In addition, effluents flowing away from RN wells were collected and analysed at various periods, after carrying out aromatic solvents squeezes. The amount of saturates, aromatics, resins, and asphaltenes (SARA analysis), of the crude oil, the deposited crude oil fraction, and the effluent’s residues were measured and compared. The asphaltenes weight percent was found to increase from 1.56% for the crude oil to 11.42% for the deposited oil fraction, and was in the range 1.37–2.36% for the effluent’s residues. Such results indicate that the deposited oil fraction and the effluent’s residues consist mainly of asphaltenes and resins.

The Colloidal Approach. A Promising Route for Asphaltene Deposition Modelling

It is now widely recognized that asphaltene exist in crude oils both as dissolved and particulate matter and that asphatenic crude oils behave as colloidal systems. The objective of this research work is to check if, in porous media and under dynamic conditions, asphaltene also behave as colloids. In this case, their deposition kinetic should obey the classical laws for colloid deposition in porous media. To achieve this, asphaltene deposition kinetics has been investigated as a function of the main controlling parameters such as flow rate, asphaltene aggregation state, resin content and crude origin. The study has been performed, first under well controlled condition using model fluids and porous media, and then under more representative conditions using actual crude oils and outcrop sandstones. The results confirmed that, indeed, the kinetics of asphaltene deposition in porous media obeys the general scaling low of colloid deposition. They allowed us to propose general scaling laws for the deposition kinetics in the form , η is the capture efficiency and γ the shear rate. The exponents s are universal exponents that are characteristic of the deposition regimes while the power law pre-factors A encompass all the specific features of the system considered (asphaltene and porous media). These kinetic laws show that the thickness of the deposit increases rapidly with decreasing shear rate. Accordingly and under favourable conditions, a thick deposit is expected to form during heavy oil extraction from high permeability formations and under low flow rate conditions. Such deposition could then have significant impact on the efficiency of heavy oil recovery. Therefore, its impact on permeability and on flow properties of reservoir fluids needs to be assessed as a part of process optimisation and evaluation. The Colloidal approach provides a new and promising route for asphaltene deposition and associated permeability damage modelling.

Experimental Investigation on Asphaltene Deposition in Porous Media During Miscible Gas Injection

In this work the likelihood of asphaltene deposition problems during dynamic displacement of oil by natural gas in unconsolidated porous media is experimentally inspected. The two different rock materials, limestone and sandstone, are used as a representative of porous media. Dynamic flow experiments indicate that the increase of natural gas injection increases asphaltene deposition in the unconsolidated matrix. The results of the study show that increase in asphaltene deposition leads to pore plugging, porosity reduction and absolute permeability damage. Irreducible water measurements showed that natural gas-induced asphaltenes change the rock wettability to oil-wet.

Adhesion and Retention of a Bacterial Phytopathogen Erwinia chrysanthemi in Biofilm-Coated Porous Media

The goal of this study is to investigate the impact of biofilm physical and biological properties on bacterial transport and deposition in porous media. Experiments were performed in packed columns to examine the removal of Erwinia chrysanthemi (Ech3937), a phytopathogen, from the bulk fluid due to its attachmentto glass beads coated with Pseudomonas aeruginosa biofilms. Two isogenic P. aeruginosa strains, PAO1 and PD0300, with different EPS secretion capabilities and EPS compositions, were used to culture biofilms. The Ech3937 transport and distribution in packed columns were studied in both upflow and downflow cell injection modes over a range of solution ionic strengths. The results show that the presence of biofilm strongly interferes with the deposition behavior of Ech3937 in porous media. The spatial variation of deposited Ech3937 cells contradicts the log-linear pattern predicted by the classic filtration theory, indicating that the biofilm physical structure and polymeric interactions between the biofilm EPS and Ech3937 cell surface are the main mechanisms that control bacterial deposition. When the biofilm accumulation is relatively small, bacterial adhesion onto biofilm-coated porous media is mainly inhibited by steric forces. By contrast, cell deposition is enhanced by the reduced porous media porosity when biofilm is more abundant.

Detection of tobacco smoke deposition by hyperpolarized krypton-83 MRI

Despite the importance of the tobacco smoke particulate matter in the lungs to the etiology of pulmonary disease in cigarette smokers, little is currently known about the spatial distribution of particle deposition or the persistence of the resulting deposits in humans, and no satisfactory technique currently exists to directly observe tobacco smoke condensate in airways. In this proof-of-principle work, hyperpolarized (hp) 83Kr MRI and NMR spectroscopy are introduced as probes for tobacco smoke deposition in porous media. A reduction in the hp-83Kr longitudinal (T1) relaxation of up to 95% under near-ambient humidity, pressure and temperature conditions was observed when the krypton gas was brought into contact with surfaces that had been exposed to cigarette smoke. This smoke-induced acceleration of the 83Kr self-relaxation was observed for model glass surfaces that, in some experiments, were coated with bovine lung surfactant extract. However, a similar effect was not observed with hp-(129)Xe indicating that the 83Kr sensitivity to smoke deposition was not caused by paramagnetic species but rather by quadrupolar relaxation due to high adsorption affinity for the smoke deposits. The 83Kr T1 differences between smoke-treated and untreated surfaces were sufficient to produce a strong contrast in variable flip angle FLASH hp-83Kr MRI, suggesting that hp-83Kr may be a promising contrast agent for in vivo pulmonary MRI.

Excess Colloid Retention in Porous Media as a Function of Colloid Size, Fluid Velocity, and Grain Angularity

The deposition and re-entrainment behaviors of five sizes of carboxylate-modified microspheres (ranging from 0.1 to 2.0 microm) were examined both in porous media and impinging jet systems under a variety of environmentally relevant pore fluid velocities (2-8 m day-'), and in both the absence and the presence of an energy barrier to deposition. The magnitudes of the deposition efficiencies were compared among the porous media and impinging jet systems under equivalent fluid velocities, solution chemistries, and surface chemistries. The observed deposition efficiencies were factors of about 5 to 50 greater in the porous media relative to the impinging jet across the entire size range of microspheres examined, demonstrating that this excess deposition in porous media is relevant to a wide range of colloid sizes. The magnitude of excess deposition increased with increasing fluid velocity, and was greatest for the smallest colloids (0.1 microm). A range between 15% and 40% of the excess retained colloids were released upon introduction of low ionic strength solution, indicating that they were retained via secondary energy minima without direct contact with the grain surfaces. The observations indicate that pore geometry is a critical governor of colloid deposition in the presence of an energy barrier, even in porous media composed of spherical collectors. A portion of this excess deposition results from retention in flow stagnation zones.

Significance of straining in colloid deposition: Evidence and implications

Considerable research suggests that colloid deposition in porous media is frequently not consistent with filtration theory predictions under unfavorable attachment conditions. Filtration theory was developed from an analysis of colloid attachment to the solid‐water interface of a single spherical grain collector and therefore does not include the potential influence of pore structure, grain‐grain junctions, and surface roughness on straining deposition. This work highlights recent experimental evidence that indicates that straining can play an important role in colloid deposition under unfavorable attachment conditions and may explain many of the reported limitations of filtration theory. This conclusion is based upon pore size distribution information, size exclusion, time‐ and concentration‐dependent deposition behavior, colloid size distribution information, hyperexponential deposition profiles, the dependence of deposition on colloid and porous medium size, batch release rates, micromodel observations, and deposition at textural interfaces. The implications of straining in unsaturated and heterogeneous systems are also discussed, as well as the potential influence of system solution chemistry and hydrodynamics. The inability of attachment theory predictions to describe experimental colloid transport data under unfavorable conditions is demonstrated. Specific tests to identify the occurrence and/or absence of straining and attachment are proposed.