Oil Recovery Applications Research Articles

Formulation and characterization of ionic liquid-based nanoemulsion for enhanced oil recovery applications

Ionic liquids (ILs) are gaining attention in enhanced oil recovery (EOR) due to their potential as emulsifiers for stable oil-in-water nanoemulsions. The unique properties and stability make them promising class of chemicals, but there is a notable lack of comprehensive studies on ILs based nanoemulsions for oil recovery. In present work two methods of emulsification viz. high energy and low energy method were utilized for nanoemulsion formulation. The properties of nanoemulsions were evaluated by droplet size, zeta potential, and stability analysis. The optimized nanoemulsion formulation was further studied for EOR by assessing its miscibility with crude oil, interfacial tension reduction, wettability change, and rheological properties. The prepared nanoemulsions exhibited droplet size in a nanoscale range which decreased with emulsifier concentration. The formulated nanoemulsion formulations revealed a significant higher value (>40 mV) of zetapotential of all the IL solutions indicates higher stability of the formulated nanoemulsions. The stability was further confirmed by multiple light scattering using Turbiscan stability analyser. The excellent miscibility of the optimized nanoemulsion with crude oil holds promise for enhanced oil recovery and industrial applications. A significant lower value interfacial tension (2 mN/m at 70 °C) was obtained at optimum formulation. The nanoemulsion also showed good wettability and altered the wettability of the rock from oil-wet to water-wet. The rheological studies of nanoemulsions showed good viscous behaviour which is desirable for improved sweep efficiency. A higher viscosity of nanoemulsion (5 cp at 30 °C and 3 cp at 30 °C) compared to water improves the macroscopic sweep efficiency. The findings of this study clearly demonstrate the ability to create extremely stable crude O/W nanoemulsion, which is desirable in enhanced oil recovery.

Citrus-Based Biopolymer for Enhanced Oil Recovery Applications in High-Salinity, High-Temperature Reservoirs

Citrus-Based Biopolymer for Enhanced Oil Recovery Applications in High-Salinity, High-Temperature Reservoirs

Evaluation of Interfacial Structure of Self-Assembled Nanoparticle Layers: Use of Standard Deviation between Calculated and Experimental Drop Profiles as a Novel Method.

The self-assembly of nanoparticles (NPs) at interfaces is currently a topic of increasing interest due to numerous applications in food technology, pharmaceuticals, cosmetology, and oil recovery. It is possible to create tunable interfacial structures with desired characteristics using tailored nanoparticles that can be precisely controlled with respect to shape, size, and surface chemistry. To address these functionalities, it is essential to develop techniques to study the properties of the underlying structure. In this work, we propose an experimental approach utilizing the standard deviation of drop profiles calculated by the Laplace equation from experimental drop profiles (STD), as an alternative to the Langmuir trough or precise microscopic methods, to detect the initiation of closely packed conditions and the collapse of the adsorbed layers of CTAB-nanosilica complexes. The experiments consist of dynamic surface/interfacial tension measurements using drop profile analysis tensiometry (PAT) and large-amplitude drop surface area compression/expansion cycles. The results demonstrate significant changes in STD values at the onset of the closely packed state of nanoparticle-surfactant complexes and the monolayer collapse. The STD trend was explained in detail and shown to be a powerful tool for analyzing the adsorption and interfacial structuring of nanoparticles. Different collapse mechanisms were reported for NP monolayers at the liquid/liquid and air/liquid interfaces. We show that the interfacial tension (IFT) is solely dependent on the extent of interfacial coverage by nanoparticles, while the surfactants regulate only the hydrophobicity of the self-assembled complexes. Also, the irreversible adsorption of nanoparticles and the increasing number of adsorbed complexes after the collapse were observed by performing consecutive drop surface compression/expansion cycles. In addition to a qualitative characterization of adsorption layers, the potential of a quantitative calculation of the parameter STD such as the number of adsorbed nanoparticles at the interface and the distance between them at different states of the interfacial layer was discussed.

Experimental Investigation of the Viscosity and Stability of Scleroglucan-Based Nanofluids for Enhanced Oil Recovery.

Biopolymers emerge as promising candidates for enhanced oil recovery (EOR) applications due to their molecular structures, which exhibit better stability than polyacrylamides under harsh conditions. Nonetheless, biopolymers are susceptible to oxidation and biological degradation. Biopolymers reinforced with nanoparticles could be a potential solution to the issue. The nanofluids' stability and performance depend on the nanoparticles' properties and the preparation method. The primary objective of this study was to evaluate the effect of the preparation method and the nanoparticle type (SiO2, Al2O3, and TiO2) on the viscosity and stability of the scleroglucan (SG). The thickening effect of the SG solution was improved by adding all NPs due to the formation of three-dimensional structures between the NPs and the SG chains. The stability test showed that the SG + Al2O3 and SG + TiO2 nanofluids are highly unstable, but the SG + SiO2 nanofluids are highly stable (regardless of the preparation method). According to the ANOVA results, the preparation method and standing time influence the nanofluid viscosity with a statistical significance of 95%. On the contrary, the heating temperature and NP type are insignificant. Finally, the nanofluid with the best performance was 1000 ppm of SG + 100 ppm of SiO2_120 NPs prepared by method II.

New Trends in Biosurfactants: From Renewable Origin to Green Enhanced Oil Recovery Applications.

Enhanced oil recovery (EOR) processes are technologies used in the oil and gas industry to maximize the extraction of residual oil from reservoirs after primary and secondary recovery methods have been carried out. The injection into the reservoir of surface-active substances capable of reducing the surface tension between oil and the rock surface should favor its extraction with significant economic repercussions. However, the most commonly used surfactants in EOR are derived from petroleum, and their use can have negative environmental impacts, such as toxicity and persistence in the environment. Biosurfactants on the other hand, are derived from renewable resources and are biodegradable, making them potentially more sustainable and environmentally friendly. The present review intends to offer an updated overview of the most significant results available in scientific literature on the potential application of biosurfactants in the context of EOR processes. Aspects such as production strategies, techniques for characterizing the mechanisms of action and the pros and cons of the application of biosurfactants as a principal method for EOR will be illustrated and discussed in detail. Optimized concepts such as the HLD in biosurfactant choice and design for EOR are also discussed. The scientific findings that are illustrated and reviewed in this paper show why general emphasis needs to be placed on the development and adoption of biosurfactants in EOR as a substantial contribution to a more sustainable and environmentally friendly oil and gas industry.

Advanced polymer‐based surfactant for improved heat and salinity stability in enhanced oil recovery processes

AbstractEnhancing oil recovery through surfactants has proven to be a successful strategy in recent times. However, traditional surfactants have their limitations, particularly in terms of stability under high temperatures and salinity levels. This study delved into a groundbreaking macromolecular polymeric surfactant, S‐AV, which holds the unique ability to transform rock surface characteristics, effectively stripping away residual oil while maintaining resilience against elevated temperatures and salinity. S‐AV was synthesized through a free‐radical copolymerization process, incorporating benzyl, perfluoroalkyl, alkyl‐, benzyl‐, ethylene glycol, and amide‐alkyl‐sulfonate groups, ultimately yielding a comb‐like molecular structure. S‐AV demonstrated exceptional prowess, swiftly reducing the underwater oil contact angle to 53.4° in just 48 h. This synthesized surfactant also retained its phase stability up to salinity levels of 36,000 ppm, with temperature having no disruptive impact on its phase stability performance. Furthermore, S‐AV showcased remarkable viscosity reduction in conditions of high temperature and salinity. The core flooding experiments underscored the potential of S‐AV, as its injection led to a significant oil recovery rate of up to 83%. These findings position S‐AV as a promising candidate for practical enhanced oil recovery applications.

Preparation and evaluation of hydroxyethyl cellulose–based functional polymer for highly efficient utilization of heavy oil under the harsh reservoir environments

Emulsification viscosity reduction and subsequent demulsification are effective strategies to improve the utilization rate of heavy oil. However, traditional surfactants are challenged by unsatisfactory salt tolerance, inadequate stability in emulsification, difficulty in demulsification and pollution problem of oily wastewater discharge. To realize the feasibility and environment-friendliness of heavy oil utilization in the harsh reservoir environments, we designed a functional polymer and conducted a comprehensive evaluation using heavy oil samples from Chenping oil well in Shengli Oilfield. It was synthesized by grafting two hydrophobic monomers, lauryl methacrylate (LMA) and N, N–Diethylaminomethyl methacrylate (DEAEMA), onto the hydrophilia hydroxyethyl cellulose (HEC) by free–radical polymerization. The viscosity reduction rate can reach 99.57 % even under the high salinity of 26,050 mg/L. The stable oil–in–water (O/W) emulsion can be maintained for >48 h, satisfying the actual requirements for heavy oil recovery. Moreover, the emulsion can be completely demulsified in a CO2 atmosphere within 30 min, suggesting its satisfactory demulsification performance. Our study achieved the one–step transformation of heavy oil emulsion between emulsification and demulsification, which provides a green bio–based material and an ingenious strategy for enhanced oil recovery and other chemical engineering applications including oil/water separation.

Experimental investigation of new derived anionic natural surfactant from peanut oil: Application for enhanced oil recovery

Nowadays, there is a growing inclination towards the environmentally friendly and economically viable materials in the field of chemical enhanced oil recovery including the surfactant flooding. This study investigates the performance of a newly developed anionic surfactant derived from peanut oil in enhanced oil recovery (EOR) applications. The validity of the formulated surfactant using the esterification and sulfonation methods was verified through FTIR, 1H NMR, and TGA analytical techniques. According to the outputs of conductivity and surface tension from developed surfactant solutions at 500 and 4000 ppm, the concentration of 2000 ppm was identified as the critical micelle concentration (CMC). Several experimental tests were applied on the surfactant solutions and more specifically at CMC range, such as IFT measurement, wettability estimation, foamability, oil displacement and emulsification. The surfactant solution at CMC (optimal surfactant solution) reduced the IFT from an initial value of 15.5 to 6.8 × 10−2 mN/m at the optimum concentration of formation water (15,000 ppm). Wettability alteration was examined on sandstone and carbonate rock samples, and the optimal surfactant solution successfully altered both rock surfaces from strongly oil-wet to water-wet, resulting in a decrease in contact angle from 144° to 58° on carbonate rock and from 138° to 44° on sandstone rock. In addition, the emulsion test results revealed a significant ability of the peanut surfactant to create emulsions. Examination of microscopic images demonstrated that the emulsion remained stable for approximately 90 days with a high compatibility under high saline conditions. Hence, the developed natural surfactant enabled to displace extra 19.3 % and 15.64 % original oil in place (OOIP) from the sandstone and carbonate core plugs, respectively, with shifting the relative permeability curves towards the lift side.

Stability Evaluation of Nanofluids Suitable for Enhanced Oil Recovery

The evaluation of metal oxides nanoparticles stability in the base fluids has become a major aspect in enhanced oil recovery process in recent years. Physical and chemical properties of ZnO nanofluids have caught attention of many researchers because they are easily dispersed in the base fluids, better convective coefficient of heat transfer, and wider bandgap which make them remarkable nanofluids candidate compared to other metal oxides. In this study, the stability of nanofluid of zinc oxide nanoparticles was evaluated using different stability tests and analysis. However, ZnO nanoparticles were synthesized using sol-gel method and nanofluids of different concentrations were prepared. The prepared nanoparticles were characterized using various characterization techniques such as XRD, FTIR, TEM, and Zeta sizer. The stability of prepared nanofluids was investigated using sedimentation test, UV-vis spectrophotometer, and zeta analyzer. Based on physical investigation and UV-vis spectra observations, ZnO nanoparticles in base fluids have shown a good colloidal stability in addition to their high zeta potential values of-43.7 (mV) after seven days which makes it a successful potential candidate for enhanced oil recovery applications.

Effects of viscosity ratio and surface wettability on viscous fingering instability in rectangular channel

This paper explores the impact of viscosity ratio and surface wettability on immiscible viscous fingering instability within a rectangular channel. Numerical investigations are conducted across a range of viscosity ratios (VR) from 0.0009 to 0.5 and wall wettability ([Formula: see text]) from 15° to 150°. The volume of fluid (VOF) model is employed to track the development of finger-shaped instability at the fluid interface. Our results indicate that higher viscosity ratios lead to increased displacement efficiency. Additionally, we find the formation of necking at low VR, which diminishes at higher VR values. The finger-shaped pattern splits into two parts at a wettability of 15°; beyond this threshold, no such splitting occurs. Furthermore, a transition from hydrophilic to superhydrophobic wettability abolishes necking, resulting in enhanced displacement efficiency. Notably, as wettability shifts from hydrophilic to super hydrophobic, instability shifts toward the left side. These findings hold relevance for applications in drug delivery, clinical processes and oil recovery.

Sodium citrate-sodium hydroxide synergy on remediating asphaltene-contaminated solids

Asphaltenes are the heaviest and surface-active polyaromatic compounds in crude oil. Their precipitation and deposition on sand surfaces switch the wettability of sand from water-wet to oil-wet, which is harmful to the oil recovery process. In this study, we demonstrate the synergistic effect between sodium hydroxide (NaOH) and sodium citrate (Na3Cit) on remediating asphaltene-contaminated silica from both experimental and molecular dynamics (MD) simulation perspectives. Asphaltene desorption efficiency increased from 39 % (Na3Cit only) to 84 % (NaOH + Na3Cit), attributed to better remediation of natural silica wettability and reduced silica-asphaltene adhesion with the co-addition chemicals. Fundamental insights for NaOH-Na3Cit synergy were revealed by MD simulation. The bonding between an asphaltene model compound (C5Pe) and the quartz (101) surface became thermodynamically less favorable when both NaOH and Na3Cit were present in the system, forcing the C5Pe molecules to move away from the surface. In summary, we highlight the NaOH-Na3Cit synergy in promoting the asphaltene detachment from silica surfaces, which has important implications in oil recovery and soil remediation applications.

Constructing a viscoelastic film for enhanced oil recovery via self-adsorption of amphiphilic nanosheets at oil-water interface

Immiscible liquid-liquid interfaces have widespread applications in drug delivery, oil-water separation, oil recovery, emulsion and foam stability, etc. Here, a dense viscoelastic interface film is constructed via the self-adsorption of amphiphilic molybdenum disulfide nanosheets at the oil-water interface, which has significant implications for enhanced oil recovery. The microscopic dispersion characteristics of amphiphilic nanosheets in water phase are characterized using Cryo-EM, and the adsorption regularities of amphiphilic nanosheets in horizontal and vertical directions of oil-water interface are also revealed. Besides the mechanical response and rheological properties of interface adsorption film are systematically studied. Experimental results demonstrate that the amphiphilic nanosheet can self-curl to form a single amphiphilic nanosheet with a size of 30 nm in the water phase as the amphiphilic nanosheets concentration is lower than 50 mg/L. When the amphiphilic nanosheets concentration reaches 100 mg/L, obvious water-phase aggregation behaviors happen. The amphiphilic nanosheets can reduce the oil-water interfacial tension from 18.47 mN/m to 0.27 mN/m by forming multilayer adsorption at the oil-water interface. The adsorption ratio of amphiphilic nanosheets from bulk phase to oil-water interface can reach 97.50 %. In addition, the oil-water interface adsorption film exhibits excellent elastic properties and higher strength because the amphiphilic nanosheets can form a planar network structure at the oil-water interface which can be also directly observed in microfluidic pores. The storage modulus and interface shear viscosity of interface adsorption film are 1.65 Pa and 1.38 mN·s/m, respectively. In theory, the required desorption energy of a single amphiphilic nanosheet from oil-water interface to bulk phase is deduced to be 587 KBT. This work is expected to provide amphiphilic molybdenum disulfide nanosheet as an effective candidate for enhanced oil recovery.

Nonionic Surfactant Blends for Enhanced Oil Recovery in High-Temperature Eagle Ford Reservoir

Summary Nonionic surfactants have proven successful and cost-effective in enhancing production from conventional and unconventional reservoirs. However, studies into the mechanism and performance of nonionic surfactants have been limited to reservoirs with temperatures below 200°F due to the temperature-dependent physiochemical properties, especially cloudpoint (CP). In this study, nonionic-ionic surfactant blends were designed to create nonionic systems with cloudpoint temperatures (CPTs) above 300°F for wettability alteration in high-temperature reservoirs like the Eagle Ford Shale in Texas, USA. Through CP, wettability, interfacial tension (IFT), and spontaneous imbibition experiments, 22 commercial surfactant samples (individual and blends) were investigated. Results showed that the amount of ionic cosurfactant affected thermal stability, with increasing concentration leading to increasing CPT. Wettability alteration was dependent not only on temperature but also on the class of ionic cosurfactant. Cationic cosurfactants were superior at improving nonionic surfactants’ thermal stability. However, they resulted in oil-wet contact angles (CAs) with increasing temperature. On the other hand, anionic cosurfactants displayed better synergy in terms of wettability alteration, creating strongly water-wet and intermediate-wet CAs at high temperatures. Therefore, the focus was placed on nonionic-anionic surfactant blends for the reservoir samples used in this study. Stable surfactant blends with CPTs from 316°F to 348°F were successfully created for enhanced oil recovery (EOR) applications at high-temperature conditions. Spontaneous imbibition studies using these blends indicated improved recovery by up to 173%. This work validates and builds upon previous studies of surfactant performance, wettability alteration, and IFT while providing new insight into nonionic surfactant blends at temperature conditions not currently available in the literature. It also serves as a template for the surfactant screening and selection process when considering nonionic surfactants.

Horizontal and Vertical Comparison of Microbial Community Structures in a Low Permeability Reservoir at the Local Scale.

Petroleum microorganisms play a crucial role in the application of microbial-enhanced oil recovery, and the community structures of petroleum microorganisms have been widely studied. Due to variations in reservoir geological conditions, reservoir microbial communities exhibit unique characteristics. However, previous studies have primarily focused on microbial community changes within a single well, a single block, and before and after water flooding, and thus, cross-horizon and cross-regional comparative studies of in situ microbial communities are lacking. In this study, the 16S rRNA full-length sequencing method was adopted to study bacterial communities in crude oil samples taken from two wells at the same depths (depths of 2425 m and 2412 m) but approximately 20 km apart in the Hujianshan oilfield, located in the Ordos Basin. At the same time, the results were combined with another layer of research data from another article (from a depth of 2140 m). The aim was to compare the differences in the microbial community structures between the oil wells on a horizontal scale and a vertical scale. The results revealed that there were minimal differences in the microbial community structures that were influenced by the horizontal distances within a small range (<20 km), while differences were observed at a larger spatial scale. However, the dominant bacteria (Proteobacteria and Bacteroidetes) in the different oilfields were similar. Vertical depth variations (>300 m) had significant impacts on the communities, and this was mainly controlled by temperature. The greater the depth, the higher formation temperature, leading to an increase in thermophilic and anaerobic bacteria within a community.

New in the range of reagents and technologies for chemical enhanced oil recovery in high-temperature reservoirs

Currently, numerous enhanced oil recovery reagents and application technologies have been developed in the domains of flow rejection and injection profile levelling. The choice of stimulation methods is reliant on the geological and physical conditions of the reservoir. Therefore, the accuracy of this choice has a direct impact on the efficiency of implementing enhanced oil recovery technologies.The current availability of low-volume chemical enhanced oil recovery reagents for high-temperature reservoirs is limited, and their effectiveness varies. This article presents the results of a pilot study from 2018 to 2021 aimed at improving oil recovery in high-temperature reservoirs. The study involves evaluating approved levelling technologies for injection profiles that use thermotropic compositions "Complex 377" and "EOR701R", as well as the polymer composition "EOR909R". The geological and physical conditions of their approbation, as well as the primary injection parameters and resulting findings, are provided.This information will be valuable to professionals engaged in enhanced oil recovery methods for oil reservoirs, as well as those working on the implementation of physical and chemical methods for the same purpose.

Process Synthesizes Janus Carbon Nanofluids From Waste Plastics for EOR

_ This article, written by JPT Technology Editor Chris Carpenter, contains highlights of paper SPE 214799, “Novel Janus Carbon Nanofluids From Waste Plastics as Sustainable Nanoagents for Enhanced Oil Recovery: Scaleup Synthesis and Performance Evaluation,” by Wei Wang, Sehoon Chang, SPE, and Ayrat Gizzatov, SPE, Saudi Aramco, et al. The paper has not been peer reviewed. _ The complete paper describes nanomaterials—Janus carbon nanofluids—derived from waste plastics and demonstrates the potential of the nanofluids as highly effective alternative nanoagents for enhanced oil recovery (EOR) applications at reservoir conditions. A novel, sustainable, cost-effective method has been developed to scale up synthesis of Janus carbon nanoparticles (JC-NPs) from waste plastic feedstock by combined pyrolysis, chemical functionalization, and pulverization, which allows for production of the JC-NPs in mass quantities at an industrial scale. Introduction Recent research has demonstrated that nanoparticles with asymmetric surface properties (i.e., Janus nanoparticles) could achieve a much higher efficiency of oil recovery factors with very low concentrations of loading compared with homogeneous nanoparticle fluids. To date, however, major challenges facing the exploration and use of Janus nanoparticles exist, impeding scalability of synthesis, tailored chemical functionalization, and the ability to introduce a diverse set of functionalities. Therefore, new methods for production of Janus nanomaterials on an industrial scale are desired. The authors present a novel technique to convert waste plastic materials into carbon-based nanomaterials for EOR applications. Waste plastics, as a low-cost feedstock, can be converted into high-value-added carbon-based microparticles through the controlled carbonization of polymers. Furthermore, the carbon microparticles (C-MPs) can be surface-functionalized by post-chemical treatment and then their chemical symmetry reduced to nanosize by a ball-milling technique. The resulting asymmetrically surface-functionalized carbon nanoparticles (i.e., Janus C-NPs) exhibit both nanoparticulate and surfactant-like properties that can be used as new nanoagents in nanofluid flooding for EOR applications. Experimental materials and measurement methodology are detailed in the complete paper. Results and Discussion Synthesis of C-MPs From Waste Polymers. Approximately 90% of the plastics produced globally consist of six types: low-density polyethylene, high-density polyethylene, polypropylene, polyvinylchloride, polystyrene, and polyethylene terephthalate (PET). Given their widespread use, these waste polymers constitute a substantial proportion of global plastic waste. Therefore, they present an opportunity to be used as precursors in the synthesis of C-MPs. This study offers an approach for repurposing these ubiquitous waste polymers. As depicted in Fig. 1, the authors propose synthesis of C-MPs through carbonization reactions using these waste polymers as feedstock. This methodology offers dual benefits. First, it presents a practical solution to the growing environmental concern posed by plastic waste. Second, it provides a cost-effective way to produce C-MPs, an essential component in many technological applications.

Application of Electromagnetic Methods for Reservoir Monitoring with Emphasis on Carbon Capture, Utilization, and Storage

The Controlled-Source ElectroMagnetic (CSEM) method provides crucial information about reservoir fluids and their spatial distribution. Carbon dioxide (CO2) storage, enhanced oil recovery (EOR), geothermal exploration, and lithium exploration are ideal applications for the CSEM method. The versatility of CSEM permits its customization to specific reservoir objectives by selecting the appropriate components of a multi-component system. To effectively tailor the CSEM approach, it is essential to determine whether the primary target reservoir is resistive or conductive. This task is relatively straightforward in CO2 monitoring, where the injected fluid is resistive. However, for scenarios involving brine-saturated (water-wet) or oil-wet (carbon capture, utilization, and storage—CCUS) reservoirs, consideration must also be given to conductive reservoir components. The optimization of data acquisition before the survey involves analyzing target parameters and the sensitivity of multi-component CSEM. This optimization process typically includes on-site noise measurements and 3D anisotropic modeling. Based on our experience, subsequent surveys tend to proceed smoothly, yielding robust measurements that align with scientific objectives. Other critical aspects to be considered are using magnetotelluric (MT) measurements to define the overall background resistivities and integrating real-time quality assurance during data acquisition with 3D modeling. This integration allows the fine tuning of acquisition parameters such as acquisition time and necessary repeats. As a result, data can be examined in real-time to assess subsurface information content while the acquisition is ongoing. Consequently, high-quality data sets are usually obtained for subsequent processing and initial interpretation with minimal user intervention. The implementation of sensitivity analysis during the inversion process plays a pivotal role in ensuring that the acquired data accurately respond to the target reservoirs’ expected depth range. To elucidate these concepts, we present an illustrative example from a CO2 storage site in North Dakota, USA, wherein the long-offset transient electromagnetic method (LOTEM), a variation of the CSEM method, and the MT method were utilized. This example showcases how surface measurements attain appropriately upscaled log-scale sensitivity. Furthermore, the sensitivity of the CSEM and MT methods was examined in other case histories, where the target reservoirs exhibited conductive properties, such as those encountered in enhanced oil recovery (EOR), geothermal, and lithium exploration applications. The same equipment specifications were utilized for CSEM and MT surveys across all case studies.

Synthesis of a polyacrylamide hydrogel modified with a reactive carbamate surfactant: Characterization, swelling behavior, and mathematical models

Hydrogels are polymeric materials that can absorb and retain large amounts of water. They have various applications in agriculture, horticulture, oil recovery, and water management. However, conventional hydrogels have limited swelling (Q), equilibrium swelling (Q∞), and water retention capacities (DQ) under different environmental conditions. In this study, we synthesized a series of hydrophobically associated hydrogels by the aqueous polymerization of acrylamide, acrylic acid, 2-acrylamide-2-methylpropanesulfonic acid, and a novel amphiphilic hydrophobic monomer (RCS-10). Further, we investigated the effects of the RCS-10 content on Q, the mechanical properties, and water retention capacity (DQ) of the hydrogels. We also examined the influence of temperature, pH, salt type and concentration, and urea concentration on Q, finding that an increase in the RCS-10 content decreased Q and increased the DQ of the hydrogels. The hydrogels exhibited high Q in distilled water, low-salt solutions, and low-urea (1 wt%) solutions. In the latter, the Q∞ was as high as 768.99 g/g. The hydrogels also showed excellent cyclic swelling performance and maintained high Q∞ (759.99 g/g) after six cycles. Crucially, the hydrophobic association hydrogels demonstrated superior swelling and water retention properties compared to conventional hydrogels. Thus, the hydrogels have applications in water management in various fields including agriculture and horticulture.

Amphoteric nano‐ and microgels with acrylamide backbone for potential application in oil recovery

AbstractAmphoteric nano‐ and microgels based on acrylamide (AAm), 3‐acrylamidopropyltrimethylammonium chloride (APTAC) and 2‐acrylamido‐2‐propanesulfonate sodium salt (AMPS) were prepared via inverse emulsion polymerization in the presence of crosslinking agent—N,N′‐methylenebisacrylamide (MBAA). Several polyampholyte nano‐ and microgel samples AAm‐APTAC‐AMPS with compositions (70:15:15, 80:10:10, and 90:5:5 mol%) were obtained and they were abbreviated as AAm70‐APTAC15‐AMPS15, AAm80‐APTAC10‐AMPS10 AAm90‐APTAC5‐AMPS5 (where the lower indexes indicate the molar concentration of monomers). The nano‐ and microgels were characterized by Fourier‐transform infrared spectroscopy, dynamic light scattering (DLS), transmission electron microscope (TEM), thermogravimetric analysis and interfacial tension measurements. The most attention was paid to the AAm80‐APTAC10‐AMPS10 microgel because its linear analog showed the best swelling capacity and the viscosifying effect for potential application in oil recovery. The influence of monomer concentration, surfactants, volume ratio of the water/organic phases, and the hydrophilic–lyophilic balance (HLB) on the average hydrodynamic size of the AAm80‐APTAC10‐AMPS10 nano‐ and microgels was studied. The size distribution of nano‐ and microgels derived from DLS data and TEM images was compared as a function of monomer concentration at constant surfactant concentration (6 wt%), HLB = 5.5 and mixture of water:oil = 60:40 vol%. Swelling of microgel particles in saline water due to the antipolyelectrolyte effect was observed. The applicability of amphoteric microgels AAm80‐APTAC10‐AMPS10 for oil recovery was tested on cores simulating the conditions of a model oil reservoir. The obtained results indicated that after the injection of around three pore volumes of the 2500 ppm microgel suspension into the sandstone core the permeability to brine decreased from 1.5 to 0.78 mD. For the first half of core sample the residual resistance factor was higher than the resistance factor, whereas for the second part of core sample these parameters were almost equal. Additional experiments with longer cores are needed to evaluate in‐depth propagation of microgels and permeability reduction in porous media.

Greener process to prepare and scale-up zwitterionic macro cyclic dihydroxy-aza-crown ether and their corresponding supramolecular pairs to enhanced oil recovery application

This manuscript discusses a green and clean route to prepare macro cyclic dihydroxy-aza-crown ether (MC-DACE) compounds, their zwitterionic derivatives, and the corresponding supramolecular pairs with a cationic surfactant. A conventional one vessel two-step process developed as the synthetic route. The first step consists of a reaction without solvent to obtain MC-DACE, and the next stage occurs in aqueous to get zwitterionic macro cyclic dihydroxy-aza-crown ether (ZWMC-DACE). We prepared the first instance in the lab scale, and a subsequent scale-up process was carried out. Green metrics were determined and performed through Andraos pentagon, showing that synthetic approaches are greener and environmentally friendly concerning other routes to prepare analog compounds. These ZWMC-DACE and corresponding supramolecular pairs with dodecyl trimethyl ammonium chloride (DTAC) have been tested with good performance in the enhanced oil recovery (EOR) application to study their wettability-altering and non-emulsion formation.