The high viscosity of heavy crude oil presents significant technical and economic challenges for its transportation through conventional methods. Emulsification of heavy crude oil in water offers a promising approach to improve flowability, especially in low-temperature regions. This study evaluates the performance of a lab-synthesized novel zwitterionic surfactant-N-Hexadecyl-N, N-dimethyl-1,2-ammonio-1-ethanecarbonate (C16-DMEAC) to formulate concentrated oil-in-water emulsions of an Indian heavy crude oil, utilizing high-frequency (26 kHz) ultrasonic waves. The surfactant was analyzed using FTIR, NMR, and TGA. Emulsions with varying oil content and surfactant concentrations were prepared to identify an optimized formulation. The rheological behavior of crude oil was examined under heating (35-70 degrees C) and emulsification using a rheometer. Static and dynamic stability of the emulsions were assessed using the bottle test and rheometry. Interfacial tension and droplet size were measured using a spinning drop tensiometer and a particle size analyzer, respectively. A laboratory-scale flow loop setup was employed to assess the pressure drop behavior of crude oil and emulsion under flow conditions. Research findings indicate that emulsification substantially improved the flow properties. The crude oil exhibited a high viscosity (2058.7 mPa.s at 50 s-1 and 35 degrees C), whereas the optimal emulsion formulation (70 vol% oil, 1.5 wt% surfactant) offered a significantly reduced viscosity (18.2 mPa.s at 50 s-1 and 25 degrees C) with 100 % stability up to 3 days. The application of the proposed zwitterionic surfactant (C16-DMEAC) in combination with ultrasonic emulsification presents a novel formulation strategy, ensuring maximum oil throughput and long-term emulsion stability for the efficient transportation of heavy crude oil.

Polymer flooding is a prominent chemical-enhanced oil recovery (cEOR) approach that boosts oil recovery by improving the viscosity of the injected water, increasing macroscopic sweep efficiency, and mobilizing residual oil through viscoelastic effects. Experimental findings indicate that viscoelasticity significantly contributes to improving oil recovery beyond traditional viscosity-driven processes. This study evaluates five polymeric samples HPAM-2625, CMC, Terpolymer FP-5115, Guar Gum, and Xanthan Gum that have the same viscosity but different viscoelastic behavior at the respective selected concentrations. Thus, the effect of their distinct viscoelastic properties on oil recovery has been analyzed. The viscoelastic properties of polymer samples were measured by rheology, and the chosen polymers were assessed for their capacity to enhance microscopic displacement efficiency by liberating entrapped oil in porous media. In the investigation, it was found that CMC, which had the highest viscoelasticity, resulted in the highest EOR efficiency of 31.73%. The novelty of this study is evaluating separate effect of viscosity and viscoelasticity on enhanced oil recovery during polymer flooding. Also, a linear relationship between polymer viscoelastic behavior and EOR efficiency has been established, which can be used to estimate EOR efficiency by viscoelastic polymer flooding using different viscoelastic polymers having equal viscosity at their respective concentrations.

Polymer flooding, which is a promising chemical enhanced oil recovery (EOR) method, leads to more efficient extraction of oil from depleted reservoirs and has proven technical and economic success in various projects where oil recovery often increases considerably. During polymer flooding, viscosity helped to maintain a favorable mobility ratio. Through increased water phase viscosity and improved sweep efficiency, polymer solutions improved oil recovery. Viscoelastic polymers can improve oil recovery beyond that of inelastic polymers by mobilizing the residual oil and increasing the microscopic displacement efficiency. These polymers can mobilize oil entrapped in porous media due to high capillary forces, rock configuration, or rock attraction by stripping, dragging, and pulling oil molecules into pore channels. In the present study, the effect of the two polymers on oil recovery and breakthrough was determined by selecting polymer concentrations to maintain similar viscosities with different viscoelastic behaviors. A rheological approach for the determination of storage, loss modulus, and relaxation modulus was adopted to determine the difference in the elastic behavior of the HPAM-2625 and carboxymethyl cellulose (CMC) polymers. At the concentrations used for the investigation, it was discovered experimentally that the CMC polymer was more elastic than HPAM-2625. A higher oil recovery due to viscoelasticity was achieved in the flooding experiment. An approximately 4.9% higher recovery was observed for a higher viscoelastic candidate, the CMC polymer. This article focused on the impact of viscoelasticity on oil recovery during polymer flooding. The results of this study can be useful for guiding polymer screening, design, and optimization for flooding in oil fields.

The high viscosity of Indian heavy crude oils makes their pipeline transportation highly complicated and challenging. A huge pressure drop is observed while transporting heavy crude through pipelines. The present article addresses this complication by preparing a surfactant stabilized heavy crude oil-in-water (O/W) emulsion of a flowable viscosity to ease flow through pipelines. Different O/W emulsion samples were prepared with varying concentrations of a novel anionic surfactant, linear alkylbenzene sulfonic acid (LABSA), to achieve an optimized formulation based on rheological and stability studies. The article also discusses the effect of varying surfactant concentrations on interfacial tension, droplet size and distribution, and zeta potential of the developed emulsions. The optimized emulsion, having 60 vol% oil and 2 wt% surfactant, was further considered to simulate and analyze the flow characteristics (static pressure and velocity profiles) across the horizontal pipelines of three different inner diameters (0.1, 0.05, and 0.025 m) under three different inlet flow velocities (0.1, 0.05, and 0.001 m/s), using a computational fluid dynamics (CFD) approach. A remarkable decrease in the viscosity of heavy crude was noted after emulsification. Subsequently, the pressure drop across the pipeline was reduced significantly by order of three for the flow of O/W emulsion when compared to that of the heavy crude oil through a pipe diameter of 0.1 m at an inlet velocity of 0.1 m/s. The static pressure drop across the pipeline decreased with the increase in the pipe diameter; in contrast, it increased with the increase in the inlet velocity. [GRAPHICS]

Bio-based surfactant flooding is encouraged as an EOR method, as it is obtained from natural sources and is economically attractive. In the present study, the EOR efficiency of a natural surfactant synthesized from rapseed oil has been simulated using ANSYS FLUENT. The process of oil recovery from a core by injection of surfactant has been simulated by incorporating core, brine, surfactant, and crude oil properties into the numerical model. Mass transfer of surfactant between the aqueous phase and crude oil has been modeled using species transport without a chemical reaction model. Species transport model has been coupled with the multiphase VOF model, where the flow of each phase is determined as per their respective viscous resistance. Experimental data of inlet pressure and oil production has been used for history matching and later used to visualize the oil flow through the porous media, concluding that simulation of surfactant flooding can be achieved by species transport model.

Drag is a major concern in microfluidic devices impacting flow stability, energy efficiency, and fluid flow control. Minimizing drag enhances performance and efficiency in various applications, such as flow stabilization microdevices, microvalves, and micropumps. Often, superhydrophobicity is utilized for drag-reduction applications. However, superhydrophobic surfaces tend to fail at higher Reynolds numbers. This paper investigates the pressure-flow characteristics of a microchannel having a superhydrophobic bottom wall with embedded air-cavities, and a deformable top membrane, both numerically and theoretically. The aim is to understand fluid flows in the deformable superhydrophobic microchannel and leverage its water-repellent property and deformability both together to reduce drag while maintaining the durability of the superhydrophobic wall. Two-way fluid–structure interaction (FSI) and unsteady volume of fluid (VOF) methods are employed for fluid–solid boundary and liquid–air interface at ridge-cavity, respectively. A novel theoretical model has been developed for the pressure-flow characteristics of a microchannel with a deformable top and superhydrophobic bottom wall. The theoretical and numerical results for pressure drop across the microchannel have shown a good agreement with a maximum deviation of 6.69%. Four distinct types of microchannels viz, smooth (S) (rigid non-textured), smooth with deformable top (SDT), smooth with superhydrophobic bottom (SSB), and smooth with superhydrophobic bottom and deformable top wall (SSBDT) have been investigated for the comparison of their pressure-flow characteristics. The Poiseuille Number ( fRe ) for SSBDT microchannel is found to be lowest with an average of 18.7% and a maximum of 23.5% lower than S microchannel at Re = 60. Up to 48.59% of reduction in pressure drop was observed for the SSBDT microchannel as compared to smooth (S) microchannel of the same dimensions. Furthermore, critical Reynolds Number (Re critical ) (at which the air–water interface breaks and super-hydrophobicity vanishes) was found to be ~ 20% higher for the SSBDT microchannel compared to the SSB microchannel. Thus, the wall compliance in the SSBDT microchannel is found to increase the capability to sustain the super-hydrophobicity at higher Re numbers. The proposed approach for drag reduction in microchannel can be vital to enhance the efficiency and capability of numerous microdevices needing high Reynolds number flows, such as high throughput cell sorters, microvalves, and micropumps.

Chemical Enhance oil Recovery (CEOR) technology is getting more attention since energy crises are getting worse and frightened. Successful application of polymer flooding depends on the evaluation of rheological and solution properties of injected slug at reservoir conditions, which is function of polymer concentration, salinity, temperature and shear rate. Poly acryl amide (PAM) is commonly used polymer in polymer flooding technique. However, comparative study with other polymers such as xanthan gum (XG) is required while selection of appropriate polymer for CEOR. In present study, the recovery efficiency of PAM and XG as a polymer has been evaluated for application as chemical EOR agent for tertiary phase polymer flooding in Upper Assam basin. The comparative study between PAM and XG has been done in terms of rheological properties. Core flooding experiment of polymer flooding has also been tested to determine the recovery efficiency of the PAM and XG polymer solutions. The results showed that these polymers exhibit favorable salt tolerance, temperature resistance, and recoverable viscosity after shearing, reasonable thickening behavior and improved viscosity enhancement properties due to presence of hydrophobic association in the polymer main chains. Core flooding experiment of polymer flooding has also been tested to determine the recovery efficiency of the PAM and XG polymer solutions. Results show that macroscopic sweep efficiency is the dominant factor during recovery. While an injection of hydrogel polymer to the reservoir is to increase a viscosity of fluid containing water so that the fluid is more difficult to flow than the oil, and as a result, the oil production increases. Shear thinning behavior was observed in case of PAM indicating predominance of the frontal advance theory. As PAM seems to be following both piston like movement and frontal advance theory it can be efficiently enhancing the macroscopic sweep efficiency as well as microscopic displacement efficiency. The overall recovery efficiency of 53% of OOIP was determined for PAM flooding. The overall recovery efficiency by XG polymer flooding was found to be 45%, signifying its lesser efficiency in comparison to PAM. Success of the projects also depends on cost analysis. Simulation by Computer Modelling Group (CMG) study has also been carried out to validate the experimental findings.

Emulsions are a form of colloid system that consists of a liquid and a liquid formation. The dispersed phase is made up of minute droplets, whereas the continuous phase or the dispersing phase is made up of the surrounding liquid. In this chapter there is discussion about the Emulsions and its types.

Petroleum industry is a major part of energy market and plays a dominant role in the global economy as the world’s prime source of fuel. Nanoemulsions are used in several operations of petroleum industry. This chapter briefly describes the application of nanoemulsions in operations such as wellbore cleaning, cleaning of oil spills, and enhanced oil recovery.

Enhanced oil recovery technologies are applied for producing oil from reservoir after primary and secondary recovery stages. Application of nanoemulsion for recovery of oil is an efficient EOR technique. This chapters describes the physico-chemical properties of nanoemulsions that leads to improvement of oil recovery from reservoirs.

Nanoemulsions can be applied as an effective EOR fluid due to its unique properties. This chapter explains the oil recovery mechanism by the application of nanoemulsion, and the challenges associated with the application of nanoemulsion in the reservoir.

Nano-emulsions are the homogenous solution forms by two immiscible liquids with nanometre size ranging from 20 to 500 nm and is stabilized by the presence of surface-active agents. These are often referred as sub-micro emulsion (SME) or mini-emulsion on the basis of their size. This chapter focuses on nano-emulsions and its applications.

Surfactant flooding is a proven enhanced oil recovery method for the recovery of trapped crude oil from the pores of the reservoir. In the present study, the applicability of a synthesized zwitterionic surfactant as an efficient EOR agent was tested, in terms of its interfacial tension reduction capability, emulsification behavior, and wettability modification behavior. Core flooding experiments conducted in sandstone core with the injection of 0.3 pore volume of chemical slug after water flooding showed 20% of additional oil recovery. The core flooding experiment was simulated using CMG-STARS simulator and history matching of relative permeability curve and its interpolation parameters were done. The validated model closely represented the experimental core flooding with very low error of 6%. The validated model helps in understanding the movement of crude oil and its interaction with the injected surfactant slug in the porous media. The validated model was further used for optimization of injected chemical slug by varying the parameters such as the surfactant concentration in the injected slug, the volume of injected chemical slug, and the injection rate of chemical slug. Each parameter had different effects on the oil recovery efficiency and cumulative oil recovery of more than 90% OOIP was obtained using model with injection of 1 PV of chemical slug containing 100 ppm of surfactant with the injection rate of 0.3 mL/min. The simulation of core flooding helped in optimization of crude oil production by zwitterionic surfactant and its implementation on field scale production by zwitterionic surfactant flooding.

Mobilization of crude oil from the subsurface porous media by emulsion injection is one of the Chemical Enhanced Oil Recovery (C-EOR) techniques. However, deterioration of emulsion by phase separation under harsh reservoir conditions like high salinity, acidic or alkaline nature and high temperature pose a challenge for the emulsion to be a successful EOR agent. Present study aims at formulation of Oil-in-Water (O/W) emulsion stabilized by Sodium Dodecyl Sulfate (SDS) using the optimum values of independent variables – salinity, pH and temperature. The influence of above parameters on the physiochemical properties of the emulsion such as average droplet size, zeta (ζ) potential, conductivity and rheological properties were investigated to optimize the properties. The influence of complex interactions of independent variables on emulsion characteristics were premeditated by experimental model obtained by Taguchi Orthogonal Array (TOA) method. Accuracy and significance of the experimental model was verified using Analysis Of Variance (ANOVA). Results indicated that the experimental models were significantly (p < 0.05) fitted with main influence of salinity (making it a critical variable) followed by its interactions with pH and temperature for all the responses studied for the emulsion properties. No significant difference between the predicted and experimental response values of emulsion ensured the adequacy of the experimental model. Formulated optimized emulsion manifested good stability with 2417.73 nm droplet size, −72.52 mV ζ-potential and a stable rheological (viscosity and viscoelastic) behavior at extensive temperature range. Ultralow Interfacial Tension (IFT) value of 2.22E-05 mN/m was obtained at the interface of crude oil and the emulsion. A favorable wettability alteration of rock from intermediate-wet to water-wet was revealed by contact angle measurement and an enhanced emulsification behavior with crude oil by miscibility test. A tertiary recovery of 21.03% of Original Oil In Place (OOIP) was obtained on sandstone core by optimized emulsion injection. Therefore, performance assessment of optimized emulsion under reservoir conditions confirms its capability as an effective oil-displacing agent.

Recent advances in formulation and designing of microemulsion with improved viscosity and an ability to reduce interfacial tension, miscibility with oil, have led to their application in enhanced oil recovery (EOR). The physicochemical properties of microemulsion varies widely depending on its composition, stability and temperature. In present study, an investigation has been made to formulate microemulsion using zwitterionic surfactant as amphiphile and mineral oil as oleic phase. The optimization of formulation of microemulsion with desired properties was obtained by response surface methodology (RSM). The accuracy and significance of model developed by RSM was tested by analysis of variance (ANOVA) and the model generated was used to analyse the effect of individual components on microemulsion formulation. The optimized microemulsion obtained using RSM was characterized by particle size and zeta potential analysis. The stability and miscibility tests of microemulsion showed excellent results for applicability in chemical EOR. The viscosity of the microemulsion was found to be around 300 mPa S at 10 s(-1) shear rate, which is highly encouraging for its application in EOR to improve the mobility ratio. The interfacial reduction and wettability alteration properties of microemulsion was also found to be superior to that of surfactant solution. The core flooding experiment showed that the optimized microemulsion was able to recover 26.83% of additional oil as compared to 20.01% of oil recovery by surfactant flooding, over the conventional water flooding. (C) 2019 Institution of Chemical Engineers. Published by Elsevier B.V. All rights reserved.

Surfactant flooding, a proven method of oil recovery from conventional reservoirs, is limited due to its adsorption on reservoir rocks. Surfactant adsorption leads to modification of wetting state of reservoirs, but it is dependent on the type of surfactant. In present study, a zwitterionic surfactant was selected to study its wettability alteration and adsorption behavior on sandstone and carbonate samples. The adsorption profile was fitted to isotherm models and best-fitted model was determined by R2 values. Zeta potential suggested hydrophilic interaction between the surface and surfactant. Increase in salinity and alkalinity had opposite effects on surfactant adsorption. Surfactant was found effective in altering the wetting state of rock surface. Increase in salinity and alkalinity was found to improve the wettability alteration effectiveness. Effective wettability alteration was also tested by spontaneous imbibition into core samples. Thus, zwitterionic surfactant was found suitable for application in both sandstone and carbonate reservoirs. (C) 2019 Elsevier Ltd. All rights reserved.

Abstract The objectives of the present study are to evaluate a zwitterionic surfactant for applicability in EOR. The surfactant was tested in terms of its salt tolerance, thermal stability, interfacial reduction capability, wettability alteration and resistance to adsorption. The effect of salinity and alkalinity was also tested on the above stated physico-chemical properties of the surfactant. The salt tolerance of the surfactant was tested by testing for precipitation of surfactant solution with increasing salinity at 30 °C and 80 °C. The thermal stability of the surfactant was tested by TGA testing. The interfacial tension of the crude oil and surfactant solution with varying surfactant concentration, salinity and alkalinity was tested by spinning drop technique. The wettability alteration by surfactant solution was tested by measuring contact angle on an oil wet sample. The adsorption study was done by measuring the concentration of surfactant after its solution was exposed to adsorption on crushed rock sample. The surfactant had salt tolerance of 20% salinity. The surfactant was found stable to 130 °C as per TGA curve. The interfacial tension (IFT) was reduced to ultralow value by surfactant solution for concentration at and above its critical micelle concentration. The presence of salt had minimal effect on the IFT reduction capability of the surfactant solution. Presence of alkali had synergetic effect on IFT reduction. The wettability of the oil wet sample was altered to preferentially water wet by surfactant. The loss of surfactant due to adsorption was found to be within recommenced range for applicability in EOR. These excellent physico-chemical properties of the zwitterionic surfactant suggest that it can be used in the mature oil fields for recovery of trapped oil.

•Synthesis of imidazolium based ionic liquid (C8mimBF4, C10mimBF4 and C12mimBF4).•Synergistic effect of NaCl and alkali on IFT reduction by the ionic liquid.•Mechanism of wettability alteration by FTIR and Zeta potential analysis.•Emulsion stability study with varying NaCl concentration at high temperature.•Ionic liquid flooding tests recovered more than 30% additional oil recoveries.