Institute of Polymer Materials and Technologies

Abstract Polymer flooding is the most successful technology for enhanced oil recovery (EOR), with a history of application spanning over 60 years worldwide. The simplicity of the technology, the development of the polymer production market, improvements in technological approaches, and high economic efficiency have enabled the implementation of polymer flooding across a wide range of geological and physical conditions. Thus, this paper examines the accelerated implementation of polymer flooding at the Uzen oil field in Kazakhstan. Our previous studies have investigated the relevance and effectiveness of polymer flooding for recovering residual mobile reserves trapped in reservoirs due to increased mobility ratios and permeability contrasts. The rationale for polymer flooding compared to other chemical flooding techniques has also been established. In this work, we outline further steps for the accelerated field implementation of polymer flooding. The methodology comprises field data analysis, laboratory screening of effective polymers, water chemical composition, experimental evaluation of polymer retention in porous media, and simulation studies integrated with rheology to set polymer viscosity targets. Laboratory optimization minimized test redundancies, accelerating the identification of best-performing polymers. The sequence of experiments was streamlined by focusing exclusively on samples most suitable for specific reservoir conditions, resulting in concise recommendations for testing methodologies tailored to unique field scenarios. In this work, we outline further steps for the accelerated field implementation of polymer flooding. To this end, a comprehensive geological and field analysis was conducted to select a pilot site, laboratory studies for screening effective polymers and choosing the optimal water source were performed, an experimental evaluation of the dynamic retention of the chosen polymer in the porous medium was carried out, and simulation studies were combined with rheological studies to determine the target viscosity of the polymer. A research plan for monitoring the process and an injection program considering specific field conditions have been developed, and finally, the feasibility of the project has been assessed. The aforementioned comprehensive work is succinctly integrated into a document titled "Project Passport," which can serve as a guide for implementing polymer flooding in other oil fields. The introduction of polymer flooding to the Uzen oil field marks a significant advancement in Kazakhstan's EOR practices. This study presents an innovative framework, distinct from conventional approaches, that offers expedited strategies for future implementation. Recommendations emphasize the integration of novel methodologies and engineering workflows to enhance efficiency, cost-effectiveness, and scalability.

PurposeThis work reports the development and characterisation of polymeric films composed of gelatin or its chemically modified derivatives (crotonoylated, itaconoylated, and methacryloylated gelatins) blended with polyvinyl alcohol (PVA). Metronidazole served as an antimicrobial drug in these formulations.MethodsThe films were produced by casting aqueous solutions of polymers, followed by solvent evaporation. Their structure and physicochemical characteristics were studied using Fourier transform infrared spectroscopy, scanning electron microscopy, and mechanical testing. The thickness of the films, their folding endurance, the surface pH, and transparency were also evaluated. The mucoadhesive performance of the films was evaluated through an ex vivo detachment technique involving freshly excised sheep vaginal tissues. In vitro cumulative drug release studies were conducted using Franz diffusion cells.ResultsThe results demonstrate that incorporating unsaturated functional groups into gelatin improves its mucoadhesive properties compared to native gelatin. The drug release experiments conducted in vitro showed that the cumulative release from pure gelatin/PVA films was found to be 49 ± 2%, whereas modified gelatins/PVA (70:30) films released ~ 64–71%.ConclusionThese findings suggest that modified gelatins could serve as effective excipients in designing mucoadhesive formulations for vaginal administration, with potential applications extending to other transmucosal drug delivery systems.Graphical

This study investigates the efficacy of high molecular weight hydrolyzed polyacrylamide (HPAM) solutions in enhancing oil recovery under high salinity conditions. The viscosity values of 0.25 wt.% HPAM solutions in 250 g∙L─1 brine with high content of divalent cations (Ca and Mg) were found to range from 11.5 to 12.6 cP for both 10% and 30% hydrolysis polymers. The displacement of 420-cP oil from sand pack models showed that injecting 3 pore volumes (PVs) of polymer solutions significantly increased the oil recovery factor, with an increment of 16─28% after the injection of 1 PV of water. The results of fractional flow calculations, along with sand pack flooding experiments, suggest that the oil recovery factor measurements are most likely overestimated by roughly 10%. An explanation for this is the plugging of pores by high molecular weight polymers. In fact, as the molecular weight increased from low to medium high and super high, it required the assumption of a much higher viscosity to achieve a fit between fractional flow predictions and actual polymer flood results. These findings highlight the potential of high molecular weight HPAM solutions to enhance oil recovery in high salinity environments and underscore the importance of using both sand pack flooding experiments and fractional flow calculations for comparing different polymers.

This mini-review briefly discusses the catalytic properties of polyampholytes, polyampholyte-metal complexes, polyampholyte-metal nanoparticles and polyampholyte-catalase conjugates. Polyampholyte-based catalysts can mimic enzyme functions, facilitating reactions like hydrolysis, decomposition, hydrogenation, and oxidation of various substrates. Special focus is given to amphoteric hydrogels and cryogels that encapsulate metal nanoparticles or enzymes. These materials have demonstrated effectiveness in the hydrogenation of nitroaromatic compounds, oxidation of disulfide and aliphatic (or aromatic) alcohols under mild conditions, both in batch and flow-through reactors. Kinetic parameters, turnover numbers (TON), turnover frequencies (TOF), and activation energies are presented for a series of specific catalytic processes. Notably, flow-through reactors exhibit significantly higher catalytic efficiency compared to batch reactors and can be used continuously for extended periods. Additionally, the review explores the potential of light-driven hydrogen and oxygen evolution reactions from water, facilitated by metal nanoparticles within amphoteric hydrogels in the presence of photosensitizers.

Abstract Composite hydrogels (CH) based on acrylamide (AAm), sodium acrylate (SA), and bentonite are prepared via free radical polymerization in the presence of cross‐linking agent—N,N‐methylene bisacrylamide (MBAA). As a result, a series of preformed particle gels (PPG) with different compositions are obtained. The CH is characterized by FTIR, mechanical analysis. The swelling behavior of CH is determined in water and brine water with different salinity. The influence of the monomer concentration, ratio of bentonite/monomers, on mechanical properties, and swelling degree of CH are studied.

Extensive laboratory and field tests have shown that the gelation response of gellan gum to saline water makes it a promising candidate for enhanced oil recovery (EOR). The objective of this mini-review is to evaluate the applicability of gellan gum in EOR and compare its efficiency to other precursors, in particular, hydrolyzed polyacrylamide (HPAM). At first, the "sol-gel" phase transitions of gellan gum in aqueous-salt solutions containing mono- and divalent cations are considered. Then the rheological and mechanical properties of gellan in diluted aqueous solutions and gel state are outlined. The main attention is paid to laboratory core flooding and field pilot tests. The plugging behavior of gellan in laboratory conditions due to "sol-gel" phase transition is discussed in the context of conformance control and water shut-off. Due to its higher strength, gellan gum gel provided ~6 times greater resistance to the flow of brine in a 1 mm-width fracture compared to HPAM gel. The field trials carried out in the injection and production wells of the Kumkol oilfield, situated in Kazakhstan, demonstrated that over 6 and 11 months, there was an incremental oil recovery of 3790 and 5890 tons, respectively. To put it into perspective, using 1 kg of dry gellan resulted in the incremental production of 3.52 m3 (or 22 bbls) of oil. The treatment of the production well with 1 wt.% gellan solution resulted in a considerable decrease in the water cut up to 10-20% without affecting the oil flow rate. The advantages and disadvantages of gellan compared to HPAM are analyzed together with the economic feasibility of gellan over HPAM. The potential for establishing gellan production in Kazakhstan is emphasized. It is anticipated that gellan gum, manufactured through fermentation using glucose-fructose syrup from Zharkent and Burunday corn starch plants, could be expanded in the future for applications in both the food industry and oil recovery.

Cross-linked polyampholyte nanogels consisting of neutral N-isopropylacrylamide (NIPAM), negatively charged sodium salt of 2-acrylamido-2-methylpropanesulfonate (AMPS), and positively charged (3-acryl-amidopropyltrimethylammonium chloride (APTAC) monomers were synthesized via conventional redox ini-tiated free radical copolymerization using N,N-methylenebis(acrylamide) (MBAA) as a cross-linking agent. The resulting nanogels were characterized by means of FTIR and 1H NMR spectroscopy, dynamic light scat-tering (DLS) and zeta-potential measurements. Surface morphology was analyzed using scanning electron microscopy. Due to the presence of thermally responsive NIPAM units and varying molar ratios of anionic (AMPS) and cationic (APTAC) units, the resulting nanogels were responsive to multiple stimuli in aqueous media and can be used for controlled delivery of dyes. Thus, the NIPAM90-APTAC7.5-AMPS2.5 nanogel with an excess of the cationic units was chosen for immobilization of the anionic dye, methyl orange (MO), whereas the NIPAM90-APTAC2.5-AMPS7.5 nanogel with an excess of the anionic units was chosen for immo-bilization of the cationic dye, methylene blue (MB). The release kinetics of the dyes from the nanogel was studied depending on the phase transition temperature and the salt content. Mechanism of the dye release from the nanogel matrix was determined using the Ritger-Peppas equation. Disappearance of the ionic con-tacts between the charged groups of the nanogels and the ionic dyes was suggested to be the main reason for the diffusion of the dyes through the dialysis membrane into the external solution.

State-of-the-art of flow-through catalytic reactors based on metal nanoparticles immobilized within the pores of nano-, micro- and macrosized polymeric gels and in the surface or hollow of polymeric membranes is discussed in this mini-review. The unique advantages of continuous flow-through nanocatalysis over the traditional batch-type analog are high activity, selectivity, productivity, recyclability, continuous operation, and purity of reaction products etc. The methods of fabrication of polymeric carriers and immobilization technique for metal nanoparticles on the surface of porous or hollow structures are considered. Several catalytic model reactions comprising of hydrolysis, decomposition, hydrogenation, oxidation, Suzuki coupling and enzymatic reactions in the flow system are exemplified. Realization of “on-off” switching mechanism for regulation of the rate of catalytic process through controlling the mass transfers of reactants in liquid media with the help of stimuli-responsive polymers is demonstrated. Comparative analysis of the efficiency of different flow-through catalytic reactors for various reactions is also surveyed.

Polyampholyte cryogels are a less considered subject in comparison with cryogels based on nonionic, anionic and cationic precursors. This review is devoted to physicochemical behavior, complexation ability and catalytic properties of cryogels based on amphoteric macromolecules. Polyampholyte cryogels are able to exhibit the stimuli-responsive behavior and change the structure and morphology in response to temperature, pH of the medium, ionic strength and water–organic solvents. Moreover, they can uptake transition metal ions, anionic and cationic dyes, ionic surfactants, polyelectrolytes, proteins, and enzymes through formation of coordination bonds, hydrogen bonds, and electrostatic forces. The catalytic properties of polyampholyte cryogels themselves and with immobilized metal nanoparticles suspended are outlined following hydrolysis, transesterification, hydrogenation and oxidation reactions of various substrates. Application of polyampholyte cryogels as a protein-imprinted matrix for separation and purification of biomacromolecules and for sustained release of proteins is demonstrated. Comparative analysis of the behavior of polyampholyte cryogels with nonionic, anionic and cationic precursors is given together with concluding remarks.

Coal distillates with boiling point below 360 produced by liquid-phase coal hydrogenation contain substantial amounts of sulfurous (S = 0.4-0.8 %), nitrous (N = 0.2-0.5 %), oxygenous ( = 1.5-2 %) and unsaturated compounds (20-25 %). To obtain low-sulfur stable motor fuel with high octane and cetane numbers it is required to process such products applying hydrotreatment processes. The published work contains the results of hydrogenation of coal distillates of Mamyt coal with the boiling point below 360 in the presence of Mo-containing catalysts deposited on the surface of skeletal nickel (Ni-Raney) are presented. It is shown that 3-5 % Mo/Ni-Re catalysts activate the hydrogenation reactions of hetero-atomic and unsaturated compounds at 420 C, 6.0 MPa. The content of nitrous bases in hydrogenate in comparison with the primary material reduces from 3.3 to 0.5 %; sulfur content reduces from 0.74 to 0.05 %; nitrogen from 0.47 to 0.01 %. The best hydrotreatment of coal distillate is performed with 5 % /Ni-R catalyst. In hydrotreated petroleum fractions the amount of paraffinic and olefinic hydrocarbons reduced almost twice and the amount of isoparaffinic hydrocarbons increased more than two times. The diagram for the conversion of the organic matter of paste is proposed. The principal diagram for obtaining components of motor fuels by hydrotreatment of distillate products of liquefaction of Mamyt coal is developed.