Extensional Effects during Viscoelastic Polymer Flooding: Understanding Unresolved Challenges

SPE Journal ◽  
2020 ◽  
Vol 25 (04) ◽  
pp. 1827-1841 ◽  
Author(s):  
Madhar S. Azad ◽  
Japan J. Trivedi
Keyword(s):  
Relaxation Time ◽  
Oil Recovery ◽  
Capillary Number ◽  
Deborah Number ◽  
Polymer Flooding ◽  
Extensional Viscosity ◽  
Extensional Rheology ◽  
Residual Oil ◽  
Pressure Profiles

Summary Several studies have tried to relate polymers’ enhanced oil recovery (EOR) potential to their viscoelastic characteristics such as onset, rheo thickening, extensional viscosity, and Deborah number (De). Contradictions prevail when it comes to reduction in residual oil saturation (Sor) during polymer flooding and the role of extensional properties. De calculated using the oscillatory relaxation time fails to explain the different pressure profiles exhibited by the viscous and viscoelastic polymers. Extensional viscosity has been ignored in many studies as the reason for additional Sor reduction based on the core-scale apparent viscosity and core-scale capillary number (Nc). In recent studies, a significant oil mobilization was shown by the viscoelastic polymers even before the critical Nc, which indicates that the capillary theory breaks out under specific conditions during polymer flooding. Moreover, the additional residual oil recovery caused by the high-salinity polymer solutions cannot be explained by the oscillatory De. In this paper, we compile and examine many such unresolved challenges from various literature with rheological and petrophysical insights. The uniaxial bulk extensional rheology is performed on the relevant polymers using a capillary breakup extensional rheometer to measure the extensional relaxation time, maximum extensional viscosity at the critical De, and strain hardening index. A detailed analysis signifies the role of extensional rheology on the viscoelastic onset, rheo thickening, and Sor reduction even under varying salinity conditions. The results also highlight the advantages of extensional rheology over oscillatory rheology and validate the capillary theory using modified capillary number.

Quantification of the Viscoelastic Effects During Polymer Flooding: A Critical Review

SPE Journal ◽  
2019 ◽  
Vol 24 (06) ◽  
pp. 2731-2757 ◽  
Author(s):  
M. S. Azad ◽  
J. J. Trivedi
Keyword(s):  
Porous Media ◽  
Relaxation Time ◽  
Oil Recovery ◽  
Deborah Number ◽  
Polymer Flooding ◽  
Mechanical Degradation ◽  
Pore Scale ◽  
Viscoelastic Models ◽  
Viscoelastic Polymer ◽  
Viscoelastic Effects

Summary Since the late 1960s, several enhanced–oil–recovery (EOR) researchers have developed various continuum and pore–scale viscoelastic models for quantifying the altered injectivity and incremental oil recovery because of the polymer's viscoelastic effects. In this paper, limitations in each of the continuum and pore–scale models are discussed. The critiques are made on the basis of the contradicting literature. Most of the earlier models rely on the exclusive use of the Deborah number to quantify the viscoelastic effects. The Deborah number overlooks mechanical–degradation effects. There exists a large difference in the magnitudes of the reported Deborah number in the literature because of the inconsistency in using different relaxation time and residential time. Oscillatory relaxation time used by most of the EOR researchers to calculate the Deborah number failed to distinguish the different porous–media behavior of the viscous and viscoelastic polymer. Therefore, the accuracy of relaxation time obtained from the weak oscillatory field for EOR applications in porous media is questionable. The main limitation with all the existing continuum viscoelastic models is the empirical reliance on coreflood data to predict the shear–thickening effects in porous media. The strain hardening index, needed for quantifying the thickening regime, cannot be obtained by the conventional shear rheological techniques. The conventional capillary number (Nc) failed to explain the reduction in residual oil saturation (Sor) during viscoelastic polymer flooding. Pore–scale viscoelastic models use the conventional oscillatory Deborah number for quantifying the polymer's viscoelastic effects on Sor reduction. However, this approach has many drawbacks. Discussions on the shortcomings of the existing viscoelastic models caution the current chemical EOR (cEOR) researchers about their applications and potential consequences. Also, this research provides a path forward for future research to address the limitations associated with the quantification of viscoelastic flow through porous media.

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%.

scholarly journals Simulation of Surfactant Oil Recovery Processes and the Role of Phase Behaviour Parameters

Energies ◽  
2019 ◽  
Vol 12 (6) ◽  
pp. 983 ◽  
Author(s):  
Pablo Druetta ◽  
Francesco Picchioni
Keyword(s):  
Oil Recovery ◽  
Phase Behaviour ◽  
Residual Oil ◽  
Two Phase ◽  
Oil Saturation ◽  
Recovery Processes ◽  
Fluid Properties ◽  
Injection Water ◽  
Finitedifference Method

Chemical Enhanced Oil Recovery (cEOR) processes comprise a number of techniques whichmodify the rock/fluid properties in order to mobilize the remaining oil. Among these, surfactantflooding is one of the most used and well-known processes; it is mainly used to decrease the interfacialenergy between the phases and thus lowering the residual oil saturation. A novel two-dimensionalflooding simulator is presented for a four-component (water, petroleum, surfactant, salt), two-phase(aqueous, oleous) model in porous media. The system is then solved using a second-order finitedifference method with the IMPEC (IMplicit Pressure and Explicit Concentration) scheme. The oilrecovery efficiency evidenced a strong dependency on the chemical component properties and itsphase behaviour. In order to accurately model the latter, the simulator uses and improves a simplifiedternary diagram, introducing the dependence of the partition coefficient on the salt concentration.Results showed that the surfactant partitioning between the phases is the most important parameterduring the EOR process. Moreover, the presence of salt affects this partitioning coefficient, modifyingconsiderably the sweeping efficiency. Therefore, the control of the salinity in the injection water isdeemed fundamental for the success of EOR operations with surfactants.

scholarly journals Differences of microscopic seepage mechanisms of water flooding and polymer flooding and prediction models of final oil recovery for conglomerate reservoir

2019 ◽  
Vol 74 ◽  
pp. 13
Author(s):  
Fengqi Tan ◽  
Changfu Xu ◽  
Yuliang Zhang ◽  
Gang Luo ◽  
Yukun Chen ◽  
...  
Keyword(s):  
Pore Structure ◽  
Polymer Solution ◽  
Oil Recovery ◽  
Particle Surface ◽  
Polymer Flooding ◽  
Water Flooding ◽  
Residual Oil ◽  
Displacement Efficiency ◽  
Oil Saturation ◽  
Oil Displacement Efficiency

The special sedimentary environments of conglomerate reservoir lead to pore structure characteristics of complex modal, and the reservoir seepage system is mainly in the “sparse reticular-non reticular” flow pattern. As a result, the study on microscopic seepage mechanism of water flooding and polymer flooding and their differences becomes the complex part and key to enhance oil recovery. In this paper, the actual core samples from conglomerate reservoir in Karamay oilfield are selected as research objects to explore microscopic seepage mechanisms of water flooding and polymer flooding for hydrophilic rock as well as lipophilic rock by applying the Computed Tomography (CT) scanning technology. After that, the final oil recovery models of conglomerate reservoir are established in two displacement methods based on the influence analysis of oil displacement efficiency. Experimental results show that the seepage mechanisms of water flooding and polymer flooding for hydrophilic rock are all mainly “crawling” displacement along the rock surface while the weak lipophilic rocks are all mainly “inrushing” displacement along pore central. Due to the different seepage mechanisms among the water flooding and the polymer flooding, the residual oil remains in hydrophilic rock after water flooding process is mainly distributed in fine throats and pore interchange. These residual oil are cut into small droplets under the influence of polymer solution with stronger shearing drag effect. Then, those small droplets pass well through narrow throats and move forward along with the polymer solution flow, which makes enhancing oil recovery to be possible. The residual oil in weak lipophilic rock after water flooding mainly distributed on the rock particle surface and formed oil film and fine pore-throat. The polymer solution with stronger shear stress makes these oil films to carry away from particle surface in two ways such as bridge connection and forming oil silk. Because of the essential attributes differences between polymer solution and injection water solution, the impact of Complex Modal Pore Structure (CMPS) on the polymer solution displacement and seepage is much smaller than on water flooding solution. Therefore, for the two types of conglomerate rocks with different wettability, the pore structure is the main controlling factor of water flooding efficiency, while reservoir properties oil saturation, and other factors have smaller influence on flooding efficiency although the polymer flooding efficiency has a good correlation with remaining oil saturation after water flooding. Based on the analysis on oil displacement efficiency factors, the parameters of water flooding index and remaining oil saturation after water flooding are used to establish respectively calculation models of oil recovery in water flooding stage and polymer flooding stage for conglomerate reservoir. These models are able to calculate the oil recovery values of this area controlled by single well control, and further to determine the oil recovery of whole reservoir in different displacement stages by leveraging interpolation simulation methods, thereby providing more accurate geological parameters for the fine design of displacement oil program.

The Research of the Dynamic Model of Oil Film in Pores

2013 ◽  
Vol 448-453 ◽  
pp. 3046-3049
Author(s):  
Run Tong Wu ◽  
Kao Ping Song ◽  
Er Long Yang
Keyword(s):  
Film Thickness ◽  
Oil Recovery ◽  
Polymer Flooding ◽  
Total Output ◽  
Residual Oil ◽  
Dynamics Model ◽  
Oil Film ◽  
Macroeconomic Conditions ◽  
Theoretical Significance ◽  
Tertiary Oil Recovery

As a mature tertiary oil recovery technology, polymer flooding has been widely used in domestic oilfields, especially in Daqing oilfield, its polymer flooding production has reached more than 25% of total output. Therefore, there are important theoretical significance and application value to do further research of polymer flooding mechanism and use to guide the production. In order to understand the mechanism of polymer flooding, polymer flooding oil film based on the decrease of residual oil range is the biggest, established the dynamics model of polymer solution displacement of rock wall oil film under the condition of tensile and shear flow. In addition, this paper discussed the effect of the oil film thickness, tensile index, dimensionless tensile coefficient as well as the power-law coefficient on oil film start, and pointed out macroeconomic conditions which is the oil film start required.

Experimental Study of the Biochemistry Method for Enhancing Oil Recovery in the Oil Reservoir after Polymer Flooding

2013 ◽  
Vol 647 ◽  
pp. 144-149
Author(s):  
Yue Hui She ◽  
Fan Zhang ◽  
Bo Xun Liang ◽  
Zheng Liang Wang ◽  
Long Jiang Yu
Keyword(s):  
Polycyclic Aromatic Hydrocarbon ◽  
Aromatic Hydrocarbon ◽  
Crude Oil ◽  
Oil Recovery ◽  
Degradation Rate ◽  
Polymer Flooding ◽  
Residual Oil ◽  
Degrading Bacteria ◽  
Profile Control ◽  
Polycyclic Aromatic

A delayed cross linked gel profile control agent is used to plug high permeable formations. Also, well nutrient fluid and microbes are injected with 50% of the heavy residual oil, after polymer flooding, in order to improve oil recovery due to the complex environment of oil reservoirs. Four strains of polycyclic aromatic hydrocarbon-degrading bacteria are selected from oilfield produced water with a high efficiency. Two of the four strains, namely BISYX17 and BISYX14, are new. Polycyclic aromatic hydrocarbon-degrading bacteria have high growth activity and they are able to reach a maximum stain concentration after being cultured 4 to 8 days, using phenanthrene as their sole carbon source. They are able to effectively degrade heavy hydrocarbon with a phenanthrene degradation rate of up to 80％, after the sample is cultured for seven days. Strain BISYX7 has the strongest phenanthrene -degrading ability, with a maximum degradation percentage of 89.89％. The strains are capable of producing dioxygenase to open rings of polycyclic aromatic hydrocarbon. The dioxygenase activity, produced by BISYX17, is able to reach 40.2 IU/mg, which is higher than the enzyme activities of a wild strain. This shows the strain has excellent potential to produce enzymes. Enzymes, produced by metabolism, have a direct degradation rate of 68% on crude oil. A core displacement simulation experiment indicates a profile control oil-displacing system is able to improve crude oil recovery efficiency by 17%, after polymer flooding. Thus, the system has excellent application potential for residual oil recovery.

Laboratory Investigations of Factors Influencing Polymer Flood Performance

1975 ◽  
Vol 15 (04) ◽  
pp. 338-346 ◽  
Author(s):  
M.T. Szabo
Keyword(s):  
Oil Recovery ◽  
Polymer Solutions ◽  
Polymer Concentration ◽  
Polymer Flooding ◽  
Mobility Control ◽  
Sweep Efficiency ◽  
Experimental Conditions ◽  
Polymer Injection ◽  
Polymer Flood

Abstract Numerous polymer floods were performed in unconsolidated sand packs using a C14-tagged, cross-linked, partially hydrolyzed ployacrylamide, and the data are compared with brine-flood performance in the same sands. performance in the same sands. The amount of "polymer oil" was linearly proportional to polymer concentration up to a proportional to polymer concentration up to a limiting value. The upper limit of polymer concentration yielding additional polymer oil was considerably higher for a high-permeability sand than for a low-permeability sand. It is shown that a minimum polymer concentration exists, below which no appreciable polymer oil can be produced in high-permeability sands. The effect of polymer slug size on oil recovery is shown for various polymer concentrations, and the results from these tests are used to determine the optimum slug size and polymer concentration for different sands. The effect of salinity was studied by using brine and tap water during polymer floods under similar conditions. Decreased salinity resulted in improved oil recovery at low, polymer concentrations, but it had little effect at higher polymer concentrations. Polymer injection that was started at an advanced stage of brine flood also improved the oil recovery in single-layered sand packs. Experimental data are presented showing the effect of polymer concentration and salinity on polymer-flood performance in stratified reservoir polymer-flood performance in stratified reservoir models. Polymer concentrations in the produced water were measured by analyzing the radioactivity of effluent samples, and the amounts of retained polymer in the stratified models are given for each polymer in the stratified models are given for each experiment. Introduction In the early 1960's, a new technique using dilute polymer solutions to increase oil recovery was polymer solutions to increase oil recovery was introduced in secondary oil-recovery operations. Since then, this new technique has attained wide-spread commercial application. The success and the complexity of this new technology has induced many authors to investigate many aspects of this flooding technique. Laboratory and field studies, along with numerical simulation of polymer flooding, clearly demonstrated that polymer additives increase oil recovery. polymer additives increase oil recovery. Some of the laboratory results have shown that applying polymers in waterflooding reduces the residual oil saturation through an improvement in microscopic sweep efficiency. Other laboratory studies have shown that applying polymer solutions improves the sweep efficiency in polymer solutions improves the sweep efficiency in heterogeneous systems. Numerical simulation of polymer flooding, and a summary of 56 field applications, clearly showed that polymer injection initiated at an early stage of waterflooding is more efficient than when initiated at an advanced stage. Although much useful information has been presented, the experimental conditions were so presented, the experimental conditions were so variable that difficulties arose in correlating the numerical data. So, despite this good data, a systematic laboratory study of the factors influencing the performance of polymer flooding was still lacking in the literature. The purpose of this study was to investigate the effect of polymer concentration, polymer slug size, salinity in the polymer bank, initial water saturation, and permeability on the performance of polymer floods. The role of oil viscosity did not constitute a subject of this investigation. However, some of the data indicated that the applied polymer resulted in added recovery when displacing more viscous oil. The linear polymer-flood tests were coupled with tests in stratified systems, consisting of the same sand materials used in linear flood tests. Thus, it was possible to differentiate between the role of polymer in mobility control behind the flood front in each layer and its role in mobility control in the entire stratified system through improvement in vertical sweep efficiency. A radioactive, C14-tagged hydrolyzed polyacrylamide was used in all oil-recovery tests. polyacrylamide was used in all oil-recovery tests. SPEJ P. 338

scholarly journals Effect of Capillary Number on the Residual Saturation of Colloidal Dispersions Stabilized by a Zwitterionic Surfactant

2021 ◽  
Vol 11 (2) ◽  
pp. 524
Author(s):  
Han Am Son ◽  
Taewoong Ahn
Keyword(s):  
Oil Recovery ◽  
Capillary Number ◽  
Colloidal Dispersion ◽  
Colloidal Dispersions ◽  
Particle Aggregation ◽  
Water Interface ◽  
Residual Oil ◽  
Zwitterionic Surfactant ◽  
Anionic Polymer ◽  
Oil Water

We investigated oil recovery from porous rock using nanoscale colloidal dispersions, formed by adsorption of an anionic polymer [poly-(4styrenesulfonic acid-co-maleic acid); PSS-co-MA] and a zwitterionic surfactant [N-tetradecyl-N, N-dimethyl-3-ammonio-1-propanesulfonate, TPS] onto silica nanoparticles. In an emulsion, colloidal dispersion enhanced the stability of the oil-water interface in the absence of particle aggregation; the hydrophobic alkyl chains of TPS shifted into the oil drop, not only physiochemically, stabilizing the oil-water interface, but also promoting repulsive particle-to-particle interaction. Core flooding experiments on residual oil saturation as a function of capillary number, at various injection rates and oil viscosities, showed that the residual oil level was reduced by almost half when the zwitterionic surfactant was present in the colloidal dispersion. Consequently, the result revealed that this colloidal dispersion at the interface provides a mechanically robust layer at the oil-water interface without particle aggregation. Thus, the dispersion readily entered the pore throat and adhered to the oil-water interface, lowering the interfacial tension and improving oil recovery.

Core-to-Field-Scale Simulations of Polymer Viscoelastic Effect on Oil Recovery Using the Extended Viscoelastic Model

2021 ◽  
Author(s):  
Mursal Zeynalli ◽  
Emad W. Al-Shalabi ◽  
Waleed AlAmeri
Keyword(s):  
Oil Recovery ◽  
Polymer Concentration ◽  
Viscoelastic Model ◽  
Polymer Flooding ◽  
Mechanical Degradation ◽  
Residual Oil ◽  
Displacement Efficiency ◽  
Field Scale ◽  
Trapping Number ◽  
Reservoir Simulator

Abstract Being one of the most commonly used chemical EOR methods, polymer flooding can substantially improve both macroscopic and microscopic recovery efficiencies by sweeping bypassed oil and mobilizing residual oil, respectively. However, a proper estimation of incremental oil to polymer flooding requires an accurate prediction of the complex rheological response of polymers. In this paper, a novel viscoelastic model that comprehensively analyzes the polymer rheology in porous media is used in a reservoir simulator to predict the recovery efficiency to polymer flooding at both core- and field-scales. The extended viscoelastic model can capture polymer Newtonian and non-Newtonian behavior, as well as mechanical degradation that may take place at ultimate shear rates. The rheological model was implemented in an open- source reservoir simulator. In addition, the effect of polymer viscoelasticity on displacement efficiency was also captured through trapping number. The calculation of trapping number and corresponding residual-phase saturation was verified against a commercial simulator. Core-scale tertiary polymer flooding predictions revealed the positive effect of injection rate and polymer concentration on oil displacement efficiency. It was found that high polymer concentration (>2000 ppm) is needed to displace residual oil at reservoir rate as opposed to near injector well rate. On the other hand, field-scale predictions of polymer flooding were performed in a quarter 5-spot well pattern, using rock and fluid properties representing the Middle East carbonate reservoirs. The field-simulation studies showed that tertiary polymer flooding might improve both volumetric sweep efficiency and displacement efficiency. For this case study, incremental oil recovery by polymer flooding is estimated at around 11 %OOIP, which includes about 4 %OOIP residual oil mobilized by viscoelastic polymers. Furthermore, the effect of different parameters on the polymer flooding efficiency was investigated through sensitivity analysis. This study provides more insight into the robustness of the extended viscoelastic model as well as its effect on polymer injectivity and related oil recovery at both core- and field-scales. The proposed polymer viscoelastic model can be easily implemented into any commercial reservoir simulator for representative field-scale predictions of polymer flooding.

Characterizing the Role of Clay and Silica Nanoparticles in Enhanced Heavy Oil Recovery During Polymer Flooding

2016 ◽  
Vol 41 (7) ◽  
pp. 2731-2750 ◽  
Author(s):  
Seyyed Shahram Khalilinezhad ◽  
Goshtasp Cheraghian ◽  
Mohammad Saber Karambeigi ◽  
Hamid Tabatabaee ◽  
Emad Roayaei
Keyword(s):  
Silica Nanoparticles ◽  
Oil Recovery ◽  
Heavy Oil ◽  
Polymer Flooding ◽  
Heavy Oil Recovery
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