R-3 Repository :: Browsing by Author "Biswal, Sibani L."

Browsing by Author "Biswal, Sibani L."

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A 2-D simulation study on CO2ﾠsoluble surfactant for foam enhanced oil recovery
(Elsevier, 2019) Zeng, Yongchao; Farajzadeh, Rouhi; Biswal, Sibani L.; Hirasaki, George J.
This paper probes the transport of CO2ﾠsoluble surfactant for foaming in porous media. We numerically investigate the effect of surfactant partitioning between the aqueous phase and the gaseous phase on foam transport for subsurface applications when the surfactant is injected in the CO2ﾠphase. A 2-D reservoir simulation is developed to quantify the effect of surfactant partition coefficient on the displacement conformance and CO2ﾠsweep efficiency. A texture-implicit local-equilibrium foam model is embedded to describe how the partitioning of surfactant between water and CO2ﾠaffects the CO2ﾠfoam mobility control when surfactant is injected in the CO2ﾠphase. We conclude that when surfactant has approximately equal affinity to both the CO2ﾠand the water, the transport of surfactant is in line with the gas propagation and therefore the sweep efficiency is maximized. Too high affinity to water (small partition coefficient) results in surfactant retardation whereas too high affinity to CO2ﾠ(large partition coefficient) leads to weak foam and insufficient mobility reduction. This work sheds light upon the design of water-alternating-gas-plus-surfactant-in-gas (WAGﾠ+ﾠS) process to improve the conventional foam process with surfactant-alternating-gas (SAG) injection mode during which significant amount of surfactant could possibly drain down by gravity before CO2ﾠslugs catch up to generate foam in situ the reservoir.
A Multiscale Study of Foam: The Phase Behavior, Transport, and Rheology of Foam in Porous Media
(2017-12-01) Zeng, Yongchao; Hirasaki, George J.; Biswal, Sibani L.
This dissertation provides an in-depth multiscale understanding of the foam flow in porous media for subsurface applications such as gas mobility control, aquifer remediation, CO2 sequestration, water production control etc. In enhanced oil recovery (EOR), gas flooding has superior crude oil displacement efficiency where the gas sweeps. However, the overall oil recovery is often not much better than that of water flooding because of viscous fingering, gravity override, and reservoir heterogeneity. Using surfactant to generate foam in situ the porous media offer promise to simultaneously address all the three issues mentioned. Yet, the successful design of foam projects requires insightful understanding of the phase/component transport and the rheology of foam flow in porous media. The first part of my research investigates the foam transport dependence on its constituent components: the effect of gas types and surfactant structures. An experimental investigation of the effect of gas type and surfactant structure is presented. The effects of gas solubility, the stability of lamellae, the surfactant Gibbs adsorption, and the gas diffusion rate across the lamellae were examined. Our experimental results showed that the steady-state foam strength is inversely correlated with the gas permeability across a liquid lamella, a parameter that characterizes the rate of mass transport. We also calculated the limiting capillary pressure for different foaming surfactants and found that foam stability is correlated with the Gibbs surface excess concentration. My research also advances the understanding of “smart” foam rheology that can improve the sweep efficiency of gas flooding in porous media. Laboratory research work was conducted to capture the effect of heterogeneity on foam using actual reservoir rocks of varied permeabilities. It is observed that foam is more stable in high permeability cores compared to low permeability cores. Such smart rheology was also visualized in a 3-layered heterogeneous micromodel at the pore-level. Foam was shown to respond to the porous media heterogeneity by separating into a relatively dry and wet regime in the high- and low-perm regions respectively. Due to the capillary continuity between the layers of different permeability, the phase separation induced a saturation step change between the layers which resulted in responsive flow resistance. In addition, understanding the foam-oil interaction is crucial to the success of foam EOR projects. In this thesis, foam strength dependence on oil was probed using nuclear magnetic resonance (NMR) imaging technique. Manganese (II) was doped into the surfactant solution to reduce the T_2 relaxation time of water in order to differentiate the NMR response from the oil. The measured apparent viscosity was mapped out with respect to different oil fractional flows and oil saturations. It is found out that the presence of oil can not only weaken the foam strength but also emulsify with the surfactant solution. Unlike the bulk foam column test with oil, the overall apparent viscosity is found to be dependent on both oil saturation (oil fractional flow) and oil composition. Moreover, improved numerical algorithm is developed to estimate foam model parameters based on laboratory-scale experiment for field-scale reservoir simulation. Both dry-out effect and shear-thinning rheology of foam were considered. The algorithm reduced the five-parameter estimation to a few simpler steps, such as linear regression and single-variable optimization, and successfully avoided the sensitivities of initial estimates and the non-uniqueness solution issues. Our improved algorithm was also compared with others reported in literature. The robustness of the algorithm was validated by varied foam systems. Last but not least, the idea of injecting the surfactant with the gas phase (WAG+S, water-alternating-gas-plus-surfactant-in-gas process) has been conceptualized for the next generation CO2 foam EOR. Some novel nonionic or switchable surfactants are CO2 soluble, thus making it possible to inject the surfactant with CO2 slugs. Since surfactant could be present in both the CO2 and aqueous phases, it is important to understand how the surfactant partitioning between the phases influences foam transport in porous media. Foam simulations were conducted in both 1-D and 2-D systems. We conclude that when surfactant has approximately equal affinity to both the CO2 and the water, the transport of surfactant is in line with the gas propagation and therefore the sweep efficiency is maximized.
A systematic approach to alkaline-surfactant-foam flooding of heavy oil: microfluidic assessment with a novel phase-behavior viscosity map
(Springer Nature, 2020) Vavra, Eric; Puerto, Maura; Biswal, Sibani L.; Hirasaki, George J.
The apparent viscosity of viscous heavy oil emulsions in water can be less than that of the bulk oil. Microfluidic flooding experiments were conducted to evaluate how alkali-surfactant-foam enhanced oil recovery (ASF EOR) of heavy oil is affected by emulsion formation. A novel phase-behavior viscosity map—a plot of added salinity vs. soap fraction combining phase behavior and bulk apparent viscosity information—is proposed as a rapid and convenient method for identifying suitable injection compositions. The characteristic soap fraction, XSorsoap, is shown to be an effective benchmark for relating information from the phase-viscosity map to expected ASF flood test performance in micromodels. Characteristically more hydrophilic cases were found to be favorable for recovering oil, despite greater interfacial tensions, due to wettability alteration towards water-wet conditions and the formation of low apparent-viscosity oil-in-water (O/W) macroemulsions. Wettability alteration and bubble-oil pinch-off were identified as contributing mechanisms to the formation of these macroemulsions. Conversely, characteristically less hydrophilic cases were accompanied by a large increase in apparent viscosity due to the formation of water-in-oil (W/O) macroemulsions.
Characterizing adsorption of associating surfactants on carbonates surfaces
(Elsevier, 2018) Jian, Guoqing; Puerto, Maura; Wehowsky, Anna; Miller, Clarence; Hirasaki, George J.; Biswal, Sibani L.
HYPOTHESIS: The adsorption of anionic surfactants onto positively charged carbonate minerals is typically high due to electrostatic interactions. By blending anionic surfactants with cationic or zwitterionic surfactants, which naturally form surfactant complexes, surfactant adsorption is expected to be influenced by a competition between surfactant complexes and surfactant-surface interactions. EXPERIMENTS: The adsorption behavior of surfactant blends known to form complexes was investigated. The surfactants probed include an anionic C15-18 internal olefin sulfonate (IOS), a zwitterionic lauryl betaine (LB), and an anionic C13-alcohol polyethylene glycol ether carboxylic acid (L38). An analytical method based on high-performance liquid chromatography evaporative light scattering detector (HPLC-ELSD) was developed to measure three individual surfactant concentrations from a blended surfactant solution. The adsorption of the individual surfactants and surfactant blends were systematically investigated on different mineral surfaces using varying brine solutions. FINDINGS: LB adsorption on calcite surfaces was found to be significantly increased when blended with IOS or L38 since it forms surfactant complexes that partition to the surface. However, the total adsorption of the LB-IOS-L38 solution on dolomite decreased from 3.09 mg/m2 to 1.97 mg/m2 when blended together compared to summing the adsorption values of individual surfactants, which highlights the importance of mixed surfactant association.
Characterizing the Influence of Organic Carboxylic Acids and Inorganic Silica Impurities on the Surface Charge of Natural Carbonates Using an Extended Surface Complexation Model
(American Chemical Society, 2019) Song, Jin; Rezaee, Sara; Zhang, Leilei; Zhang, Zhuqing; Puerto, Maura; Wani, Omar B.; Vargas, Francisco; Alhassan, Saeed; Biswal, Sibani L.; Hirasaki, George J.
In this work, we developed an extended surface complexation model (SCM) that successfully fits all tested ζ-potential data (63 in total) of synthetic calcite and three natural carbonates (Iceland spar, Indiana limestone, “SME” rock from a Middle East field) in brines with divalent ions in a wide range of ionic strengths (0.001–0.5 M). To develop this extended model, our previous reported SCM is first optimized by incorporating the ζ-potential of synthetic calcite in a wide range of ionic strength (0.001–0.5 M) along with previously published data for parameter refitting. The model is then applied to predict the surface charge of synthetic calcite in concentrated solutions up to 5 M NaCl to reveal the role of high salinity in calcite wettability. Eventually, the model is extended to fit the ζ-potential of natural carbonates by adding surface reactions for impurities such as silica and organic-based carboxylic acids. The coverage of the organic impurities is found to be essential for explaining why the ζ-potential of natural carbonates is more negative compared to that of synthetic calcite. Naphthenic acid (assumed to have one carboxylic group) and humic/fulvic acid (assumed to have six carboxylic groups) are tested in the model calculation as possible sources of surface impurities to demonstrate the effect of the number of carboxylic groups in the acid molecule. Finally, the effect of a humic acid pretreatment on the ζ-potential of synthetic calcite is investigated experimentally to verify the assumption that absorbed organic impurities on the calcite surface contribute significantly to a more negatively charged natural carbonate surface when compared to that of pure calcite surfaces.
Destabilization, Propagation, and Generation of Surfactant-Stabilized Foam during Crude Oil Displacement in Heterogeneous Model Porous Media
(American Chemical Society, 2018) Xiao, Siyang; Zeng, Yongchao; Vavra, Eric D.; He, Peng; Puerto, Maura; Hirasaki, George J.; Biswal, Sibani L.
Foam flooding in porous media is of increasing interest due to its numerous applications such as enhanced oil recovery, aquifer remediation, and hydraulic fracturing. However, the mechanisms of oil-foam interactions have yet to be fully understood at the pore level. Here, we present three characteristic zones identified in experiments involving the displacement of crude oil from model porous media via surfactant-stabilized foam, and we describe a series of pore-level dynamics in these zones which were not observed in experiments involving paraffin oil. In the displacement front zone, foam coalesces upon initial contact with crude oil, which is known to destabilize the liquid lamellae of the foam. Directly upstream, a transition zone occurs where surface wettability is altered from oil-wet to water-wet. After this transition takes place, a strong foam bank zone exists where foam is generated within the porous media. We visualized each zone using a microfluidic platform, and we discuss the unique physicochemical phenomena that define each zone. In our analysis, we also provide an updated mechanistic understanding of the "smart rheology" of foam which builds upon simple "phase separation" observations in the literature.
Effect of Surfactant Partitioning Between Gaseous Phase and Aqueous Phase onﾠCO2ﾠFoam Transport for Enhanced Oil Recovery
(Springer, 2016) Zeng, Yongchao; Ma, Kun; Farajzadeh, Rouhi; Puerto, Maura; Biswal, Sibani L.; Hirasaki, George J.
CO2 flood is one of the most successful and promising enhanced oil recovery technologies. However the displacement is limited by viscous fingering, gravity segregation and reservoir heterogeneity. Foaming the CO2 and brine with a tailored surfactant can simultaneously address these three problems and improve the recovery efficiency. Commonly chosen surfactants as foaming agents are either anionic or cationic in class. These charged surfactants are insoluble in either CO2 gas phase or supercritical phase and can only be injected with water. However, some novel nonionic or switchable surfactants are CO2 soluble, thus making it possible to be injected with the CO2 phase. Since surfactant could be present in both CO2 and aqueous phases, it is important to understand how the surfactant partition coefficient influences foam transport in porous media. Thus, a 1-D foam simulator embedded with STARS foam model is developed. All test results, from different cases studied, have demonstrated that when surfactant partitions approximately equally between gaseous phase and aqueous phase, foam favors oil displacement in regard with apparent viscosity and foam propagation speed. The test results from the 1-D simulation are compared with the fractional flow theory analysis reported in literature.
Enhance the Rolling Resistance of Natural Rubber via Silicone Chemistry Reagent and Study its Rheological Properties
(2021-04-12) Alenezi, Moneer S; Biswal, Sibani L.
Natural rubber (NR) has been preferable to its counterpart synthetic due to the remarkable mechanical properties and as a greener alternative material to the synthetic rubber. Rolling resistance (RR) enhancement is desired to minimize carbon dioxide (CO2) emissions produced via vehicle footprint. A reinforcing silica filler without any incompatibility among silica molecules and NR particles has shown to enhance the silica/polymer interactions within NR, leading to lower the rolling resistance. Silica has proved to improve the mechanical properties such as tensile strengths and toughness, resulting in green NR tires, that has potential to replace synthetic rubber. In this MS thesis, the impacts of silica to the micro-structure of NR, the crosslinking process, and the rheological properties of NR are investigated through numerous approaches. Characterization of the network structure and aggregates formed in NR micro-structure due to silica addition are determined via optical microscope and scanning electron microscope (SEM). The fractal dimension of different aggregates size formed via addition of silica is calculated using MATLAB image processing. Various types of surfactants are examined to stabilize the NR with silica and observe the rubber particles response. Rheological properties of concentrated NR and viscoelastic properties of NR with silica addition are carried out through ARES-G2 rheometer. Results displayed in this thesis are manifested that silica reinforced NR can form a robust network. Sodium Dodecyl Sulfate (SDS) surfactant is tested effectively to provide a stability in NR structure without forming aggregations. The rheological results are demonstrated the various viscoelastic behavior of NR with manipulating silica amount addition.
Evaluating the Transport Behavior of CO2ﾠFoam in the Presence of Crude Oil under High-Temperature and High-Salinity Conditions for Carbonate Reservoirs
(American Chemical Society, 2019) Jian, Guoqing; Zhang, Leilei; Da, Chang; Puerto, Maura; Johnston, Keith P.; Biswal, Sibani L.; Hirasaki, George J.
An amine-based surfactant, Duomeen TTM, was evaluated for foam flooding in carbonate rock at high temperature (120 °C), high salinity (22% total dissolved solids), and CO2–oil miscible conditions. We demonstrate enhanced oil recovery by utilizing CO2 foam under miscible conditions in the presence of crude oil. The foam was generated in situ by both co-injection and surfactant alternating gas injection modes. Foam transport and propagation were characterized as a function of the foam quality, shear rate, permeability, surfactant concentration, and method of injection. Finally, we utilize the experimental results to obtain the parameters for the STARS foam model by optimizing multiple variables related to the dry out, shear thinning, and surfactant concentration effects on foam transport. Enhanced oil recovery utilizing CO2 foam under miscible conditions in the presence of SMY crude oil was able to decrease oil saturation to 3.0%. It was also determined that significantly more injected pore volumes were required for the foam to reach the steady state in the presence of SMY crude oil. A foam simulation process in a heterogeneous reservoir is conducted applying the parameters obtained. The TTM CO2 foam generated significantly reduces the mobility of CO2 in the high permeability layers, which results in an improved swept volume in the low permeability zone that significantly improves oil recovery when epoil = 1 and fmoil = 0.5. Oil saturation parameters play important roles in the effectiveness of CO2 foam: large epoil and small fmoil will reduce the efficiency for TTM CO2 foam.
Foam EOR for Carbonate Reservoirs: from Lab Evaluation to Pilot Field Test
(2020-04-23) Zhang, Leilei; Biswal, Sibani L.; Hirasaki, George J.
Enhanced oil recovery (EOR) techniques have changed how we recover oil more efficiently. The injection of surfactant foamed gas can mitigate the poor sweep efficiency caused by reservoir heterogeneity, density differential, and viscous fingering effects. How to tune foam strength, foam rheology, and foam collapse properties depends highly on reservoir conditions. This dissertation provides comprehensive study of foam transport design in porous media including formulation screening, lab scale evaluation, pilot field test, and produced emulsion treatment. These studies provide a full life cycle analysis for EOR foam. Low surfactant adsorption is required to control the cost of successful foam applications. In carbonate reservoirs, cationic surfactants and nonionic surfactants usually have low adsorption compare to more commonly used anionic surfactants. The studied switchable cationic surfactant (TTM) adsorption is low on pure carbonate surface, but relatively high on natural carbonate surface due to the presence of siliceous minerals. The diamine surfactant adsorption is dominated by electrostatic attraction. Lower adsorption can be achieved by modifying the electrostatic interaction by: (a) decreasing the solution pH, (b) adding ions for charge screening (effectiveness: monovalent
Foam Transport in Porous Media: in-Situ Capillary Pressure Measurement and Application to Enhanced Heavy Oil Recovery
(2021-12-03) Vavra, Eric Daniel; Biswal, Sibani L.; Hirasaki, George J.
Aqueous foam flow in porous media has been the subject of an increasing number of studies in recent years. Foam is a dynamic colloid that can exhibit unintuitive properties when flowing in porous media; thus, foam experiments often produce unclear or conflicting results. With potentially lucrative applications ranging from enhanced oil recovery (EOR) to subterranean CO2 storage, there is great incentive to understand the fundamental physiochemical processes that accurately describe and predict the nature of flowing foam in porous media. One important aspect of foam flowing in porous media is stability. Many variables, such as quality of the foam, permeability of the medium, velocities of the phases, and type of gas, can influence foam stability. Classically, foam strength is thought to be governed by the stability of liquid lamellae that separate individual gas bubbles and by the a “limiting” capillary pressure above which foam lamellae rupture. In this thesis, a custom probe was designed and constructed for directly measuring in-situ capillary pressures of foam in porous media. Foam quality scan experiments were conducted primarily in a 143-Darcy sand pack with AOS14-16-stabilized N2 foam at ambient lab conditions and constant gas flow rates. Capillary pressure was observed to increase with increasing foam quality before plateauing over a range of qualities in the low-quality regime. Then, in contrast to the classical view, capillary pressure decreased with increasing foam quality in the high-quality regime. The measured capillary pressure decreases were correlated with in-situ observations of increasing bubble size. These general trends occurred regardless of gas velocity over the range of velocities that were tested. Increasing velocity led to increasing transition foam qualities and plateau capillary pressures. This finding implies that the foam mechanisms which are a function of velocity, such as foam generation by lamella division, were significant in determining the behavior of the foam in porous media. Additionally, several other findings improved understanding of foam flow in the sand pack. A nearly constant transition liquid velocity, separating the low- and high-quality regimes, was identified regardless of gas velocity. The rheology of the N2 foam was found to be shear thinning in the low-quality regime and described by a power law model with an exponent of -0.9. In the high-quality regime, the behavior of the coarse bubble and continuous-gas flow systems was weakly shear thinning or, at the slowest velocities, nearly Newtonian as expected for gas flow alone. Comparing gas composition with N2 or CO2 tests revealed the same transition foam quality but different apparent viscosities and capillary pressures. Trends with absolute pressure and temperature are also discussed. An application of interest in this thesis is foam EOR. Generally, foams collapse in the presence of crude oil, but foaming formulations can be chemically engineered to interact synergistically with oil. In this thesis alkali-surfactant-foam (ASF) EOR for the recovery of viscous and heavy oils was documented. For this process, careful characterization of the physiochemical interactions among aqueous, oleic, gas, and solid phases is a must. To aid in this, a novel phase-behavior viscosity map was developed to conveniently select optimal injection conditions. The map is constructed from phase behavior test results as a function of log(added salinity) vs. soap fraction and from viscosities measured by the falling sphere method. For the viscous oil that was tested, conditions resulting in low-viscosity oil-in-water (O/W) emulsions were the most favorable. The characteristic soap fraction was selected as a benchmark to relate dynamic flow behavior in micromodel experiments to static phase behavior in sealed pipettes. Microfluidic devices have proven to be useful for visualizing and confirming flow processes of foam in porous media that would otherwise be much more challenging to observe. For this reason, microfluidic devices mimicking porous media were designed for multiphase flow characterization. A detailed description for the construction of oil-resistant polymer micromodels is provided in this thesis. This micromodel platform was utilized to conduct four microflooding experiments. Foam was found to be stable across all flooding experiments. The experimental results at different characteristic soap fractions and salinities were found to be consistent with predictions made based on the phase-viscosity map. The microfluidic platform also provided new insights into the role of wettability alteration and emulsion formation. In the most hydrophilic case (FE1-), 90% of the 5,855 cP heavy oil was recovered at an apparent viscosity of 820 cP. This result was made possible by wettability alteration towards water-wet and the formation of low apparent-viscosity O/W macroemulsions. Conversely, the most hydrophobic case (FE2) resulted in a lower total oil recovery (70%) accompanied by a large increase in apparent viscosity, likely due to the formation of water-in-oil (W/O) macroemulsions, as predicted by referencing the phase-behavior viscosity map. Additionally, wettability alteration and bubble-oil pinch-off were identified as contributing mechanisms to the formation of O/W macroemulsions in the more hydrophilic flooding experiments. Foam was more effective at recovering oil in these cases presumably due to more favorable mobility control.
Insights on Foam Transport from a Texture-Implicit Local-Equilibrium Model with an Improved Parameter Estimation Algorithm
(American Chemical Society, 2016) Zeng, Yongchao; Muthuswamy, Aarthi; Ma, Kun; Wang, Le; Farajzadeh, Rouhi; Puerto, Maura; Vincent-Bonnieu, Sebastien; Akbar Eftekhari, Ali; Wang, Ying; Da, Chang; Joyce, Jeffrey C.; Biswal, Sibani L.; Hirasaki, George J.
We present an insightful discussion on the implications of foam transport inside porous media based on an improved algorithm for the estimation of model parameters. A widely used texture-implicit local-equilibrium foam model, STARS, is used to describe the reduction of gas mobility in the state of foam with respect to free gas. Both the dry-out effect and shear-dependent rheology are considered in foam simulations. We estimate the limiting capillary pressure Pc* from fmdryvalues in the STARS model to characterize foam film stability in a dynamic flowing system. We find that Pc* is a good indicator of foam strength in porous media and varies with different gas types. We also calculate Pc* for different foaming surfactants and find that foam stability is correlated with the Gibbs surface excess concentration. We compare our improved parameter estimation algorithm with others reported in literature. The robustness of the algorithm is validated for various foam systems.
Lattice-Boltzmann Modeling of Potential Fluid Flow Impairment Caused by Asphaltene Deposition in Porous Media
(2018-11-30) Lin, Pei-Hsuan; Vargas, Francisco; Biswal, Sibani L.; Akin, John E.
Asphaltene deposition in porous media has significant effects on oil flow during primary and secondary oil production. When asphaltenes deposit in porous media, the pore throats become plugged, leading to the impairment of permeability, and in turn causes several difficulties for oil production. In order to solve the problem of asphaltene deposition in porous media, it is important to understand the mechanism of asphaltene deposition in order to find measures to mitigate this problem. Moreover, a predictive model would greatly help control and reduce asphaltene deposition at the early stage. However, the mechanism of asphaltene deposition in porous media is still unclear. Only a few deposition models have been proposed and most of them have too many fitting parameters. Hence, the objective of this study is to propose a new model which has a fewer number of fitting parameters but still effectively predicts asphaltene deposition. Furthermore, the validity of the proposed model will be verified by microchannel and core flooding experiments. Instead of using the traditional Computational Fluid Dynamics (CFD) methods, such as the Finite Element Method, Finite Difference Method, and Finite Volume Method, the Lattice Boltzmann Method (LBM) is employed to model asphaltene deposition in porous media. The benefit of using LBM for simulating fluid flow in complex geometric settings is that it is comparatively easier for computational implementation and parallel computing due to being a meshless technique. Once the mechanism of asphaltene deposition in porous media has been understood clearly, mitigation methods can be then applied to prevent asphaltene deposition. Also, the simulation tool that is developed using LBM can help reduce the cost involved in experiments, which is extremely important in the petroleum industry.
Microfluidic Devices for Characterizing Pore-scale Event Processes in Porous Media for Oil Recovery Applications
(Journal of Visualized Experiments, 2018) Vavra, Eric D.; Zeng, Yongchao; Xiao, Siyang; Hirasaki, George J.; Biswal, Sibani L.
Microfluidic devices are versatile tools for studying transport processes at a microscopic scale. A demand exists for microfluidic devices that are resistant to low molecular-weight oil components, unlike traditional polydimethylsiloxane (PDMS) devices. Here, we demonstrate a facile method for making a device with this property, and we use the product of this protocol for examining the pore-scale mechanisms by which foam recovers crude oil. A pattern is first designed using computer-aided design (CAD) software and printed on a transparency with a high-resolution printer. This pattern is then transferred to a photoresist via a lithography procedure. PDMS is cast on the pattern, cured in an oven, and removed to obtain a mold. A thiol-ene crosslinking polymer, commonly used as an optical adhesive (OA), is then poured onto the mold and cured under UV light. The PDMS mold is peeled away from the optical adhesive cast. A glass substrate is then prepared, and the two halves of the device are bonded together. Optical adhesive-based devices are more robust than traditional PDMS microfluidic devices. The epoxy structure is resistant to swelling by many organic solvents, which opens new possibilities for experiments involving light organic liquids. Additionally, the surface wettability behavior of these devices is more stable than that of PDMS. The construction of optical adhesive microfluidic devices is simple, yet requires incrementally more effort than the making of PDMS-based devices. Also, though optical adhesive devices are stable in organic liquids, they may exhibit reduced bond-strength after a long time. Optical adhesive microfluidic devices can be made in geometries that act as 2-D micromodels for porous media. These devices are applied in the study of oil displacement to improve our understanding of the pore-scale mechanisms involved in enhanced oil recovery and aquifer remediation.
Recyclable amine-functionalized magnetic nanoparticles for efficient demulsification of crude oil-in-water emulsions
(Royal Society of Chemistry, 2018) Wang, Qing; Puerto, Maura C.; Warudkar, Sumedh; Buehler, Jack; Biswal, Sibani L.
Produced water from the oil and gas industry often contains stable crude oil-in-water emulsions that are typically difficult to treat with conventional separation methods. Amine-functionalized nanoparticles have demonstrated effective destabilization of crude oil-in-water emulsions by associating with natural surfactants present at the oilﾖwater interface leading to separation of oil from water under an external magnetic field. Effects of magnetic demulsifier concentration, reaction time and initial oil content of emulsion on the demulsification efficiency were investigated. The demulsification efficiency of emulsions can reach as high as 99.7% by the magnetic demulsifier. Our findings characterize the demulsification process as a function of nanoparticle concentration and elucidate the governing interactions between NH2-MNPs and emulsion droplets. Another important feature of this magnetic demulsifier is its capability to be recovered by solvent-washing and reused for subsequent demulsification cycles. The recovered magnetic demulsifier was proven to be effective in demulsifying O/W emulsion for at least 6 cycles, revealing its recyclability. Demulsification of O/W emulsions with NH2-MNPs has great potential as an efficient strategy for oil removal from produced water.
Role of Gas Type on Foam Transport in Porous Media
(American Chemical Society, 2016) Zeng, Yongchao; Farajzadeh, Rouhi; Eftekhari, Ali Akbar; Vincent-Bonnieu, Sebastien; Muthuswamy, Aarthi; Rossen, William R.; Hirasaki, George J.; Biswal, Sibani L.
We present the results of an experimental investigation of the effect of gas type and composition on foam transport in porous media. Steady-state foam strengths with respect to three cases of distinct gases and two cases containing binary mixtures of these gases were compared. The effects of gas solubility, the stability of lamellae, and the gas diffusion rate across the lamellae were examined. Our experimental results showed that steady-state foam strength is inversely correlated with gas permeability across a liquid lamella, a parameter that characterizes the rate of mass transport. These results are in good agreement with existing observations that the foam strength for a mixture of gases is correlated with the less soluble component. Three hypotheses with different predictions of the underlying mechanism that explain the role of gas type and composition on foam strength are discussed in detail.
Surface Complexation Modeling of Calcite Zeta Potential Measurements in Brines with Mixed Potential Determining Ions (Ca2+, CO32-, Mg2+, SO42-) for Characterizing Carbonate Wettability
(Elsevier, 2017) Song, Jin; Zeng, Yongchao; Wang, Le; Duan, Xindi; Puerto, Maura; Chapman, Walter G.; Biswal, Sibani L.; Hirasaki, George J.
This study presents experiment and surface complexation modeling (SCM) of synthetic calcite zeta potential in brine with mixed potential determining ions (PDI) under various CO2 partial pressures. Such SCM, based on systematic zeta potential measurement in mixed brines (Mg2+, SO42−, Ca2+ and CO32−), is currently not available in the literature and is expected to facilitate understanding of the role of electrostatic forces in calcite wettability alteration. We first use a double layer SCM to model experimental zeta potential measurements and then systematically analyze the contribution of charged surface species. Calcite surface charge is investigated as a function of four PDIs and CO2 partial pressure. We show that our model can accurately predict calcite zeta potential in brine containing a combination of four PDIs and apply it to predict zeta potential in ultra-low and pressurized CO2 environments for potential application in enhanced oil recovery in carbonate reservoirs. Model prediction reveals that calcite surface will be positively charged in all considered brines in pressurized CO2 environment (>1 atm). The calcite zeta potential is sensitive to CO2 partial pressure in the various brine in the order of Na2CO3 > Na2SO4 > NaCl > MgCl2 > CaCl2 (Ionic strength = 0.1 M).
Switchable Diamine Surfactants for CO2 Mobility Control in Enhanced Oil Recovery and Sequestration
(Elsevier, 2014) Elhag, Amro S.; Chen, Yunshen; Reddy, Prathima P.; Noguera, Jose A.; Ou, Anne Marie; Hirasaki, George J.; Nguyen, Quoc P.; Biswal, Sibani L.; Johnston, Keith P.
The design of switchable amine surfactants for CO2 EOR in carbonate reservoirs at high temperatures is challenging because of the increase in the pH due to dissolution of calcium carbonate at acidic conditions. The increased pH hinders the protonation of the surfactant and its aqueous solubility. In this work, the addition of a second amine headgroup ensured that C16-18 N(EO) C3N(EO)2 is soluble in 22%TDS brine at neutral pH conditions. Also, captive bubble tensiometry measurements confirmed the activity of the surfactant at the C-W interface by large reduction in the interfacial tension coupled with high adsorption. Also, the surfactant generated viscous foam that can stabilize the displacement front in CO2 EOR processes and decrease the mobility of CO2 for enhanced CO2 sequestration.

Browsing by Author "Biswal, Sibani L."

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