Some Aspects of Polymer Retention in Porous Media Using a C14-Tagged Hydrolyzed Polyacrylamide

1975 ◽  
Vol 15 (04) ◽  
pp. 323-337 ◽  
Author(s):  
M.T. Szabo
Keyword(s):  
Porous Media ◽  
Oil Recovery ◽  
Pore Volume ◽  
Produced Water ◽  
Polymer Concentration ◽  
Oil Saturation ◽  
Polymer Flow ◽  
Hydrolyzed Polyacrylamide ◽  
Polymer Retention ◽  
Inaccessible Pore Volume

Abstract Numerous single-phase flow and oil-recovery tests were carried out in unconsolidated sands and Berea sandstone cores using C14-tagged, hydrolyzed polyacrylamide solutions. The polymer-retention polyacrylamide solutions. The polymer-retention data from these flow tests are compared with data obtained from static adsorption tests. Polymer concentrations in produced water in Polymer-flooding tests were studied using various Polymer-flooding tests were studied using various polymer concentrations, slug sizes, salt polymer concentrations, slug sizes, salt concentrations, and different permeability sands. Results show that polymer retention by mechanical entrapment had a dominant role in determining the total polymer retention in short sand packs. However, the role of mechanical entrapment was less in the large-surface-area Berea cores. In oil-recovery tests, high polymer concentrations were noted at water breakthrough in sand-pack experiments, an indication that the irreducible water was not displaced effectively ahead of the polymer slug. However, in similar tests with Berea cores, a denuded zone developed at the leading edge of the polymer slug. polymer slug. The existence of inaccessible pore volume to polymer flow is shown both in sand packs and in polymer flow is shown both in sand packs and in sandstone cores. Absolute polymer-retention values show an almost linear dependency on polymer concentration. The effect of polymer slug size on absolute polymer retention is also discussed. Distribution of retained polymer in sand packs showed an exponential decline with distance. The "dynamic polymer-retention" values in short sand packs showed much higher vales than the ‘static packs showed much higher vales than the’ static polymer-adsorption" values caused by mechanical polymer-adsorption" values caused by mechanical entrapment. The mechanism of polymer retention in silica sands and sandstones is described, based on the observed phenomenon. Introduction It is widely recognized that, as polymer solution flows in a porous medium, a portion of the polymer is retained. It is evident that both physical adsorption and mechanical entrapment contribute to polymer retention. The question of the relative importance of these retention mechanisms has not been studied adequately. The effect of residual oil saturation on polymer retention and the polymer retention during the displacement of oil from porous media has also been studied inadequately. Mungen et al. have reported a few data on polymer concentration in produced water in oil-recovery tests. However, no produced water in oil-recovery tests. However, no comparison was made between polymer retention at 100-percent water saturation and at partial oil saturation. It has been shown that the actual size of the flowing polymer molecules, with the associated water, can approach the dimensions of certain smaller pores found in porous media. Therefore, an inaccessible pore volume exists in which no polymer flow occurs. In this study, the existence polymer flow occurs. In this study, the existence of inaccessible pore volume is shown clearly, both in sand and sandstone. Although polymer-retention values have been reported for various conditions, correlation is difficult because of the differing conditions of measurements. The effect of slug size, polymer concentration, salinity, and type of porous media on polymer retention has not been systematically studied. The purpose of this study was to develop answers to these questions, rather than to provide adsorption data for actual field core samples. For this reason, unconsolidated silica sands were used in most of the experiments reported. This permitted identical, uniform single-layer and multilayer porous media to be constructed for repeated experiments under varying test conditions. Some experiments were also carried out in Berea sandstone cores to determine whether sand-pack results can be extrapolated to consolidated sandstones. Using a C 14-tagged polymer provided a very rapid, simple, and accurate polymer-concentration determination technique. SPEJ P. 323

Effect of Concentration on HPAM Retention in Porous Media

SPE Journal ◽  
2014 ◽  
Vol 19 (03) ◽  
pp. 373-380 ◽  
Author(s):  
Guoyin Zhang ◽  
R.S.. S. Seright
Keyword(s):  
Porous Medium ◽  
Porous Media ◽  
Polymer Solution ◽  
Polymer Concentration ◽  
Retention Mechanism ◽  
Dynamic Measurements ◽  
Polymer Molecules ◽  
Adsorbed Polymer ◽  
Hydrolyzed Polyacrylamide ◽  
Polymer Retention

Summary This paper investigates the effect of hydrolyzed polyacrylamide (HPAM) polymer concentration on retention in porous media by use of both static and dynamic measurements. Consistent results by use of these two methods show that different polymer-retention behaviors exist in dilute, semidilute, and concentrated regions. In both the dilute and concentrated regions, polymer retention has little dependence on concentration. In contrast, in the semidilute region, polymer retention is concentration dependent. If a porous medium is first contacted sufficiently with dilute polymer solution to satisfy the retention, no significant additional retention occurs during exposure to higher HPAM concentrations. On the basis of the experimental results, a concentration-related retention mechanism is proposed that considers the orientation of the adsorbed polymer molecules and the interaction between molecular coils in solution. By use of this model, we explain why polymer retention does not show much dependence on concentration in the dilute and concentrated regimes. Further, in the semidilute region, we explain how moderate coil interactions lead to mixed adsorbed-polymer orientation and magnitude on rock surfaces, and retention becomes concentration dependent. In field applications of polymer and chemical floods, reduced polymer retention may be achieved by first injecting a low-concentration polymer bank.

Field vs. Laboratory Polymer-Retention Values for a Polymer Flood in the Tambaredjo Field

2014 ◽  
Vol 17 (03) ◽  
pp. 314-325 ◽  
Author(s):  
R.N.. N. Manichand ◽  
R.S.. S. Seright
Keyword(s):  
Oil Recovery ◽  
Pore Volume ◽  
High Surface ◽  
High Surface Area ◽  
High Permeability ◽  
Permeable Rock ◽  
Polymer Flood ◽  
Production Wells ◽  
Polymer Retention ◽  
Inaccessible Pore Volume

Summary During a polymer flood, polymer retention can have a major impact on the rate of polymer propagation through a reservoir, and consequently on oil recovery. A review of the polymer-retention literature revealed that iron and high-surface-area minerals (e.g., clays) dominate polymer-retention measurements in permeable rock and sand (>100 md). A review of the literature on inaccessible pore volume (IAPV) revealed inconsistent and unexplained behavior. A conservative approach to design of a polymer flood in high-permeability (>1 darcy) sands would assume that IAPV is zero. Laboratory measurements using fluids and sands associated with the Sarah Maria polymer flood in Suriname suggested polymer retention and IAPV values near zero [0±20 μg/g for retention and 0±10% pore volume (PV) for IAPV]. A procedure was developed using salinity-tracer and polymer concentrations from production wells to estimate polymer retention during the Sarah Maria polymer flood in the Tambaredjo reservoir. Field calculations indicated much higher polymer-retention values than those from laboratory tests, typically ranging from approximately 50 to 250 μg/g. Field cores necessarily represent an extremely small fraction of the reservoir. Because of the importance of polymer retention, there is considerable value in deriving polymer retention from field results, so that information can be used in the design of project expansions.

Retention and Flow Characteristics of Polymer Solutions in Porous Media

1977 ◽  
Vol 17 (02) ◽  
pp. 111-121 ◽  
Author(s):  
J.G. Dominguez ◽  
G.P. Willhite
Keyword(s):  
Porous Media ◽  
Flow Rate ◽  
Polymer Solutions ◽  
Polymer Concentration ◽  
Flow Characteristics ◽  
Porous Matrix ◽  
Polymer Molecules ◽  
Partially Hydrolyzed Polyacrylamide ◽  
Hydrolyzed Polyacrylamide ◽  
Polymer Retention

Abstract Retention and flow characteristics of a solution containing Pusher 700, a high-molecular-weight, partially hydrolyzed polyacrylamide, were studied partially hydrolyzed polyacrylamide, were studied in an 86-md core made by compacting Teflon powder. The quantity, of polymer retained during linear displacement experiments ranged from 10 to 21 mu gm/gm for polymer concentrations of 100 to 500 ppm in 2-percent NaCl solutions. Nearly all retention ppm in 2-percent NaCl solutions. Nearly all retention was attributed to mechanical entrapment because of low polymer adsorption on the Teflon surface. Flow rate affected polymer retention. In increase in velocity was accompanied by polymer retention. Polymer was expelled when the flow rate was Polymer was expelled when the flow rate was reduced. Inaccessible pore volume was about 19 percent of the total pore volume. percent of the total pore volume.Resistance factors in different sections of the core ranged Pam 2 to 10 /or solutions of 100 to 500 ppm polymer concentration in 2-percent NaCl. ppm polymer concentration in 2-percent NaCl. Permeability reduction resulting from polymer Permeability reduction resulting from polymer retention produces the resistance factor in most of the core at a velocity of 3.2 ft/D. Resistance factors in the Teflon cores were two to three times lower than those reported for natural porous media where polymer is also retained by adsorption. Introduction The search for a low-cost, effective mobility control agent is currently focused on dilute aqueous solutions containing partially hydrolyzed polyacrylamides or polysaccharides. Rheological polyacrylamides or polysaccharides. Rheological properties have been studied, including the properties have been studied, including the effects of polymer concentration, shear rate, electrolyte concentration, and type of electrolyte. Correlation of rheological data and models with the flow behavior of polymer solutions in porous media has been complicated by the many interactions that occur between the complex porous matrix and the polymer solutions. Some data have been correlated using non-Newtonian rheological models to describe the variation of fluid viscosity with the apparent shear rate that the fluid experiences as it flows through the tortuous paths in porous media. These correlations have adjustable parameters determined from the particular set of parameters determined from the particular set of data used to develop the correlation. Investigators studying partially hydrolyzed polyacrylamide solutions observed apparent polyacrylamide solutions observed apparent viscosities 5 to 20 times the values measured in a conventional viscometer at the shear rates believed to exist in the porous media. These viscosity increases were not anticipated from the rheological behavior of the fluids. Pye introduced the concept of the resistance factor to quantify this effect. Burcik observed a decrease in the mobility of brine in a Berea sandstone disk that had been previously contacted with partially hydrolyzed previously contacted with partially hydrolyzed polyacrylamide. The mobility reduction persisted polyacrylamide. The mobility reduction persisted even after 100 PV of brine had been flushed through the disk. Burcik concluded that polymer molecules retained in the pore structure by adsorption or mechanical entrapment were hydrophillic and restricted the flow of water. Gogarty made an extensive experimental study of partially hydrolyzed polyacrylamide solutions in porous media and concluded that these polymer porous media and concluded that these polymer solutions reduced the permeability of the porous media. He noosed that polymer retention in natural cores occurred by mechanical entrapment and adsorption. Both mechanisms contributed to the resistance and residual or flushed resistance factors observed with polyacrylamide solutions. Other evidence of interactions between the polymer solution and the porous matrix was found. polymer solution and the porous matrix was found. Adsorption of polymer molecules on the surface of materials present in the porous matrix has been demonstrated in batch adsorption experiments. Material-balance calculations made on the streams entering and leaving porous media following step changes in concentrations show retention of polymer molecules in the porous media. polymer molecules in the porous media. A dependence of polymer retention on flow rate has been reported. Szabo devised a set of static and flow experiments in which polymer adsorption was held to a low level by using silica sand with a small surface area. Mechanical entrapment was found to be the dominant retention mechanism in short sand packs. packs. SPEJ P. 111

Micellar Flooding The Propagation of the Polymer Mobility Buffer Bank

1978 ◽  
Vol 18 (01) ◽  
pp. 5-12 ◽  
Author(s):  
S.P. Gupta
Keyword(s):  
Pore Volume ◽  
Pore Space ◽  
Polymer Concentration ◽  
Propagation Rate ◽  
Field Application ◽  
Water Mixing ◽  
Shear Degradation ◽  
Polymer Retention ◽  
Inaccessible Pore Volume ◽  
Space Volume

Abstract This study shows the factors that affect the polymer mobility buffer bank, that is, slug size and polymer mobility buffer bank, that is, slug size and concentration. The slug size is a function of polymer/chase-water mixing, polymer inaccessible polymer/chase-water mixing, polymer inaccessible pore volume (IPV), and polymer retention. The pore volume (IPV), and polymer retention. The designed polymer concentration depends on polymer apparent viscosity and, to varying degrees, on shear degradation. The polymer/chase-water mixing-zone volume at a given mobility ratio is the same for glycerine (classical miscible fluid), biopolymer, and polyacrylamide. However, the propagation rate of the polyacrylamide. However, the propagation rate of the mining zone is much higher for polymer than for glycerine because of IPV. Therefore, a larger polymer bank is required to protect the micellar polymer bank is required to protect the micellar slug than would be indicated by mixing-zone volume alone. IPV increased as polymer concentration decreased over the investigated range. A micellar fluid ahead of the polymer bank increased IPV. When polyacrylamides are used in the mobility buffer bank, their concentration should be increased to compensate for the effect of shear degradation. For each field application, shear-degradation tests should be conducted in field cores using field brine and at anticipated sand-face velocities. The loss of polyacrylamide effectiveness because of shear degradation should be determined from apparent viscosity measurement of the sheared polymer, not from polymer concentration, Brookfield viscosity, or screen factor. Introduction In a micellar flood, water-soluble polymers are used as a mobility buffer to protect the micellar slug from invasion by high-mobility chase water. In addition, polymer may be added to the micellar fluid to adjust viscosity, to improve sweep in a waterflood, as a preflush in micellar flood to improve the sweep, to control water production in producers, and for selective partial plugging of high-permeability thief zones. Biopolymers (Xanthan gum) and polyacrylamides are two classes of polymers most commonly used in oil recovery processes. processes. When designing a polymer slug for field application, proper sizing and chemical concentration are critical variables. In a micellar flood, the polymer-mobility buffer-bank size depends on polymer inaccessible pore volume (IPV), mixing, polymer inaccessible pore volume (IPV), mixing, and polymer retention. Because the primary purpose of the polymer bank is to provide adequate mobility control, a sufficient polymer concentration must be selected. However, the concentration for polyacrylamides often must be increased to account polyacrylamides often must be increased to account for losses resulting from shear degradation. This study was undertakento determine the magnitude of and variables affecting polymer inaccessible pore volume (IPV),to characterize the effect of IPV on polymer/chase-water mixing behavior, andto examine polyacrylamide shear degradation. In these IPV and mixing studies, the biopolymer is Kelzan MF TM (Xanflood); and the polyacrylamide is Dow Pusher 500. In shear polyacrylamide is Dow Pusher 500. In shear degradation studies, the polyacrylamides are Dow Pusher 500, Pusher 700, and Amoco Chemicals Pusher 500, Pusher 700, and Amoco Chemicals Sweepaid 105 (an experimental polymer). POLYMER INACCESSIBLE PORE VOLUME POLYMER INACCESSIBLE PORE VOLUME Polymers propagate through porous media more rapidly than through their carrier water. The pore space volume available for polymer flow is pore space volume available for polymer flow is less than the volume available to water. The volume in which polymer cannot flow commonly is called polymer inaccessible pore volume (IPV). The polymer inaccessible pore volume (IPV). The exact mechanism of IPV is not clear. However, it has been estimated that the polymer molecule size is of the same order as pore sizes in rock. In many cases, the smaller rock pores are not capable of transporting polymer molecules, but can transport water. Another phenomenon possibly contributing to IPV is the inability of the polymer molecule center to get near the pore wall. As a result, the average velocity of the polymer molecules is greater than that of water molecules. SPEJ p. 5

Influence of Polymer-Molecule/Wall Interactions on Mobility Control

1981 ◽  
Vol 21 (05) ◽  
pp. 613-622 ◽  
Author(s):  
J.L. Duda ◽  
E.E. Klaus ◽  
S.K. Fan
Keyword(s):  
Porous Media ◽  
Shear Rate ◽  
Pore Volume ◽  
Xanthan Gum ◽  
Mobility Control ◽  
Permeability Reduction ◽  
Polymer Flow ◽  
Inaccessible Pore Volume ◽  
Wall Interactions ◽  
Low Shear

Abstract This paper presents the results of a study of molecule/wall interactions on permeability modification of consolidated porous media by polymer solutions. The experiments were conducted with a newly developed low-shear porous media viscometer. This is a simple-to-use, versatile instrument that is particularly useful for measurements at the low shear rates characteristic of reservoir flooding. The key for obtaining reproducible, steadystate results was to expose the porous medium to several hundred pore volumes of polymer solution to saturate it with polymer. The effective permeability during polymer flow and the residual permeability were determined for xanthan gum and polyacrylamide solutions in Berea sandstone, Bradford sandstone, filter papers, and Nuclepore filters. A mechanistic interpretation of the coupling of adsorption, mechanical entrapment, shear rate, and inaccessible pore volume effects on the effective and residual permeabilities was developed. This is the first study to show that inaccessible pore volume can influence the residual permeability significantly. Introduction Solutions of high-molecular-weight polymers are being used as modified waterfloods and to control the mobility of the waterflood that follows the chemical slug in enhanced oil recovery. Currently, two distinctly different polymers are used most commonly for this application. The most popular mobility-control polymer is partially hydrolyzed polyacrylamide. This polyelectrolyte is sensitive to electrolytes and is susceptible to mechanical degradation. The second most frequently used mobility-control polymer is a polysaccharide called xanthan gum. This biopolymer is produced by a fermentation process and is less sensitive to electrolytes and shear degradation than polyacrylamide. Polyacrylamide increases the viscosity of aqueous solutions and causes changes in the permeability of porous media by adsorption and mechanical entrapment in pores whose dimensions are the same order of magnitude as the dimensions of the polymer in solutions. Numerous investigators have shown that polyacrylamide reduces the permeability of porous media during flow and that some of this permeability reduction is permanent. It generally is considered that xanthan gum reduces the mobility of a solution in porous media mainly by increasing the viscosity of the solution and that the action of the xanthan gum on the permeability is insignificant.The purpose of this study is to investigate the influence of polymer-molecule/wall interactions on mobility control. This investigation uses studies on the flow of xanthan gum and polyacrylamide solutions in various kinds of porous media with a wide range of characteristics. Although the permeability modification caused by xanthan gum molecules is not as pronounced as that caused by polyacrylamide, the polymer/wall interactions with this biopolymer are significant. Results of permeability-reduction studies during polymer flow and the residual permeability reduction as functions of shear rate, initial permeability, hydrodynamic size of polymer molecule in solution, electrolyte (NaCl) concentration, polymer concentration, and porous media characteristics are reported. The experiments were conducted with a newly developed low-shear porous media viscometer. Permeability modifications during and after polymer flow can be determined accurately with this simple instrument that eliminates the need for pumps and pressure measuring devices. The results of this investigation have been used to develop a mechanistic interpretation for the influence of molecule/wall interactions on mobility, which incorporates adsorption, mechanical entrapment, shear rate, and inaccessible pore volume effects. SPEJ P. 613^

Determination of Adsorption-Retention Constants and Inaccessible Pore Volume for High-Molecular Polymers

2021 ◽  
Author(s):  
Konstantin Mikhailovich Fedorov ◽  
Tatyana Anatolyevna Pospelova ◽  
Aleksandr Vyacheslavovich Kobyashev ◽  
Aleksandr Yanovich Gilmanov ◽  
Tatyana Nikolaevna Kovalchuk ◽  
...  
Keyword(s):  
Inverse Problem ◽  
Oil Recovery ◽  
Pore Volume ◽  
Polymer Concentration ◽  
Experimental Studies ◽  
Front Propagation ◽  
Polymer Transport ◽  
Non Destructive ◽  
Inaccessible Pore Volume

Abstract The application of chemical enhanced oil recovery methods is based mainly on data from experiments. Determining the adsorption constants without destroying the sample remains a relevant problem. It is necessary for accurate data. The determination of filtration parameters of high-molecular polymers in a porous medium using special model is considered in this paper. The aim of the investigation is the solution of inverse problem of polymer transport with adsorption. The key data for this are the characteristic times of the polymer front propagation, water and rock densities, porosity, and initial polymer concentration. The solutions of the direct problem and the inverse problem from the characteristic form of equations are obtained. The algorithm of interpretation of adsorption-retention parameters and inaccessible pore volume form non-destructive experimental studies is developed. Comparison of the calculated values of the inaccessible pore volume with the results of laboratory studies leads to an error within 10%. The practical application of the algorithm was carried out using the data obtained in previously conducted experiments.

scholarly journals SURFACTANT-POLYMER FLOODING PERFORMANCE IN HETEROGENEOUS TWO-LAYERED POROUS MEDIA

2011 ◽  
Vol 12 (1) ◽  
pp. 31-38 ◽  
Author(s):  
Muhammad Taufiq Fathaddin ◽  
Asri Nugrahanti ◽  
Putri Nurizatulshira Buang ◽  
Khaled Abdalla Elraies
Keyword(s):  
Porous Media ◽  
Oil Recovery ◽  
Polymer Flooding ◽  
Water Flooding ◽  
Residual Oil ◽  
Oil Saturation ◽  
Reservoir Heterogeneity ◽  
Residual Oil Saturation ◽  
Layered Porous Media ◽  
Multiple Porosity

In this paper, simulation study was conducted to investigate the effect of spatial heterogeneity of multiple porosity fields on oil recovery, residual oil and microemulsion saturation. The generated porosity fields were applied into UTCHEM for simulating surfactant-polymer flooding in heterogeneous two-layered porous media. From the analysis, surfactant-polymer flooding was more sensitive than water flooding to the spatial distribution of multiple porosity fields. Residual oil saturation in upper and lower layers after water and polymer flooding was about the same with the reservoir heterogeneity. On the other hand, residual oil saturation in the two layers after surfactant-polymer flooding became more unequal as surfactant concentration increased. Surfactant-polymer flooding had higher oil recovery than water and polymer flooding within the range studied. The variation of oil recovery due to the reservoir heterogeneity was under 9.2%.

Coreflood Model Calibration for Alkali Surfactant Polymer Process from a High Salinity Reservoir to Design an ASP Pilot

2021 ◽  
Author(s):  
Marisely Urdaneta
Keyword(s):  
Numerical Simulation ◽  
Simulation Model ◽  
Oil Recovery ◽  
Water Saturation ◽  
Polymer Concentration ◽  
Chemical Flooding ◽  
Adsorption Parameters ◽  
Oil Saturation ◽  
The Core ◽  
Asp Flooding

Abstract This paper aims to address calibration of a coreflood Alkali Surfactant Polymer (ASP) formulation experiment through parametrization of fluid-fluid and rock-fluid interactions considering cation exchange capacity and by rock to guide an ASP pilot design. First of all, a series of chemical formulation experiments were studied in cores drilled from clastic reservoir so that displacement lab tests were run on linear and radial cores to determine the potential for oil recovery by ASP flooding and recommended the chemical formulation and flooding schemes, in terms of oil recovery. Therefore, to simulate the process, those tests performed with radial core injection were taken, because this type of test has a better representation of the fluid flow in reservoir, the fluids are injected by a perforation in the center of the core, moving in a radial direction the fluids inside the porous medium. Subsequently, displaced fluids are collected on the periphery of the core carrier and stored in graduated test tubes. The recommended test was carried out to the phase of numerical simulation and historical matching. Reservoir simulation is one of the most important tools available to predict behavior under chemical flooding conditions and to study sensitivities based on cost-effective process implementation. Then, a radial core simulation model was designed from formulation data with porosity of 42.6%, a pore volume (PV) of 344.45 ml, radius of 7.17 cm and weight of 1225.84 g. The initial oil saturation was 0.748 PV (257.58 ml), with a critical water saturation of 0.252 PV (86.78 ml). For the simulation model historical matching, adjustments were made until an acceptable comparison was obtained with laboratory test production data through parameterization of relative permeability curves, chemical adsorption parameters, polymer viscosity, among others; resulting in an accumulated effluents production mass 37% greater for alkali than obtained in the historical, regarding to surfactant the deviation was 8% considered acceptable and for the polymer the adjustment was very close. For the injector well bottom pressure, the viscosity ratio of the mixture was considered based on the polymer concentration and the effect of the shear rate on the viscosity of the polymer as well as the effect of salinity in the alkali case. Finally, a calibrated coreflood numerical simulation model was obtained for ASP flooding to design an ASP Pilot with a residual oil saturation of 0.09 PV (31 ml) meaning 64% more recovered oil compared to a waterflooding case.

Polyacrylamide Adsorption and Readsorption in Sandstone Porous Media

SPE Journal ◽  
2019 ◽  
Vol 25 (01) ◽  
pp. 497-514 ◽  
Author(s):  
Vitor H. S. Ferreira ◽  
Rosangela B. Z. L. Moreno
Keyword(s):  
Oil Recovery ◽  
Polymer Concentration ◽  
Polymer Adsorption ◽  
Mobility Control ◽  
Polymer Molecule ◽  
Type I ◽  
Type Iv ◽  
Polymer Retention ◽  
Successive Injection ◽  
Flowing Solution

Summary The term polymer retention describes all mechanisms that remove the polymer from the flowing solution, with adsorption being its primary cause. This phenomenon can lead to detrimental effects during polymer enhanced oil recovery (EOR). In this paper, we present an investigation of dynamic polymer adsorption in sandstone-outcrop cores using polymer solutions. We study the effects of permeability and polymer concentration on the adsorption under two conditions: on virgin cores (adsorption) and a previously polymer-flooded core (readsorption). According to the results, two concentration plateaus and two regions of concentration-dependent adsorption characterize the polymer adsorption in a virgin porous medium, following a proposed Type IV isotherm. The transition between the first plateau and the second adsorption region occurs near to the overlapping concentration from dilute to semidilute regimes (cp*). Polymer readsorption increases slightly with the successive injection of banks with a higher polymer concentration, following a Type I (Langmuir) isotherm. For that case, we propose a readsorption mechanism on the basis of the desorption of a polymer molecule section and the adsorption of a new free polymer molecule. The adsorption and readsorption isotherms are similar until cp*, while the adsorption is much higher than readsorption for concentrations higher than cp*. Therefore, if the polymer concentration of the mobility control bank is greater than cp*, the total polymer loss during field applications can be reduced by preinjecting a polymer bank of lower concentration.

A network model for capture of emulsion droplets in porous media

2008 ◽  
Vol 48 (1) ◽  
pp. 21
Author(s):  
Changhong Gao
Keyword(s):  
Porous Media ◽  
Enhanced Oil Recovery ◽  
Network Model ◽  
Oil Recovery ◽  
Produced Water ◽  
Permeability Reduction ◽  
Oil Droplets ◽  
New Approach ◽  
Reservoir Rocks ◽  
Emulsion Droplets

Capture of emulsion droplets in porous media can be costly or beneficial. When produced water is injected into reservoir for pressure maintenance, the oil droplets in produced water can plug reservoir rocks and cause the well to lose injectivity. Enhanced oil recovery (EOR) technology takes advantage of this feature and plugs high-injectivity zones with emulsions. Previous studies reveal that interception and straining are the mechanisms of permeability decline. Established models rely on filtration data to determine key parameters. In this work, a network model is proposed to simulate capture of oil droplets in reservoir rocks and resultant permeability reduction. The model is validated with test data and reasonably good results are obtained. The simulation also reveals that the wettability of the tested porous media was altered by injection of emulsions. The new approach considers the characteristics of the porous media and incorporates the damage mechanisms, thus providing more scientific insights into the flow and capture of droplets in porous media.

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