A holistic approach to determine the enhanced oil recovery potential of hydroxyethylcellulose, tragacanth gum and carboxymethylcellulose

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.

Microbial communities succession post to polymer flood demonstrate a role in enhanced oil recovery

The role of indigenous microbial communities in residual oil extraction following a recovery process is not well understood. This study investigated the dynamics of resident microbial communities in oil-field simulating sand pack bioreactors after the polymer flooding stage resumed with waterflooding and explored their contribution to the oil extraction process. The microbial community succession was studied through high-throughput sequencing of 16S rRNA genes. The results revealed alternating dominance of minority populations, including Dietzia sps., Acinetobacter sps., Soehngenia sps., and Paracoccus sps., in each bioreactor following the flooding process. Additionally, the post-polymer waterflooding stage led to higher oil recovery, with hydroxyethylcellulose, tragacanth gum, and partially hydrolyzed polyacrylamide polymer-treated bioreactors yielding additional recovery of 4.36%, 5.39%, and 3.90% residual oil in place, respectively. The dominant microbial communities were previously reported to synthesize biosurfactants and emulsifiers, as well as degrade and utilize hydrocarbons, indicating their role in aiding the recovery process. However, the correlation analysis of the most abundant taxa showed that some species were more positively correlated with the oil recovery process, while others acted as competitors for the carbon source. The study also found that higher biomass favored the plugging of high permeability zones in the reservoir, facilitating the dislodging of crude oil in new channels. In conclusion, this study suggests that microbial populations significantly shift upon polymer treatment and contribute synergistically to the oil recovery process depending on the characteristics of the polymers injected. KEY POINTS: • Post-polymer flooded microbial ecology shows unique indigenous microbial consortia. • Injected polymers are observed to act as enrichment substrates by resident communities. • The first study to show successive oil recovery stage post-polymer flood without external influence.

Preparation of gum tragacanth/poly (vinyl alcohol)/halloysite hydrogel using electron beam irradiation with potential for bone tissue engineering

Nanocomposite hydrogels based on tyramine conjugated gum tragacanth, poly (vinyl alcohol) (PVA), and halloysite nanotubes (HNTs) were prepared by electron beam irradiation and characterized. The FTIR, ¹H NMR, and TGA results confirmed the chemical incorporation of HNTs into gum tragacanth. Gel content and swelling of hydrogels decreased with HNTs loading up to 20 % wt. The mechanical strength of hydrogels increased by increasing HNTs content up to 10 % with 371 kPa fracture stress at 0.95 fracture strain, compared to 312 kPa stress at 0.79 strain for gum tragacanth/PVA hydrogel. Hydrogel's biocompatibility and osteogenic activity were tested by seeding rabbit bone marrow mesenchymal stem cells. The cell viability was >85 % after 7 days of culture. In vitro secretion of ALP and calcium deposition on hydrogels in alizarin red assay after 21 days of culture indicated hydrogel potential for bone tissue engineering.

Molecular Insights into Cyclodextrin-Adamantane-Modified Copolymer Host-Guest Interactions

Supramolecular polymer flooding has great potential in solving the problems of difficult injection and low recovery in low-permeability polymer reservoirs. However, the self-assembly mechanism of supramolecular polymers is not yet to be fully understood at the molecular level. In this work, molecular dynamics simulations were used to explore the formation of cyclodextrin and adamantane-modified supramolecular polymer hydrogels; the self-assembly mechanism was summarized; and the effect of concentration on the oil displacement index was evaluated. The assembly mechanism of supramolecular polymers can be attributed to the "node-rebar-cement" mode of action. At the same time, Na⁺ can form intermolecular and intramolecular salt bridges with supramolecular polymers, and together with the "node-rebar-cement" mode of action, the supramolecular polymers can form a more compact 3D network structure. When the polymer concentration was increased, especially up to its critical association concentration (CAC), the association increased significantly. Besides, the construction of a 3D network was promoted, which results in a higher viscosity. This work investigated the assembly process of supramolecular polymers from the molecular scale and explained its mechanism of action, which makes up for the deficiencies of other research methods and provides a theoretical basis for screening out functional units that can be used for the supramolecular polymer assembly.

Application of Polymers for Chemical Enhanced Oil Recovery: A Review

Polymers play a significant role in enhanced oil recovery (EOR) due to their viscoelastic properties and macromolecular structure. Herein, the mechanisms of the application of polymeric materials for enhanced oil recovery are elucidated. Subsequently, the polymer types used for EOR, namely synthetic polymers and natural polymers (biopolymers), and their properties are discussed. Moreover, the numerous applications for EOR such as polymer flooding, polymer foam flooding, alkali–polymer flooding, surfactant–polymer flooding, alkali–surfactant–polymer flooding, and polymeric nanofluid flooding are appraised and evaluated. Most of the polymers exhibit pseudoplastic behavior in the presence of shear forces. The biopolymers exhibit better salt tolerance and thermal stability but are susceptible to plugging and biodegradation. As for associative synthetic polyacrylamide, several complexities are involved in unlocking its full potential. Hence, hydrolyzed polyacrylamide remains the most coveted polymer for field application of polymer floods. Finally, alkali–surfactant–polymer flooding shows good efficiency at pilot and field scales, while a recently devised polymeric nanofluid shows good potential for field application of polymer flooding for EOR.