Влияние полимеров и сополимеров олефинов на турбулентное течение углеводородных жидкостей

Drag reducing additives (DRA) are widely used to increase the pipeline capacity in oil and refined products transit. Introducing DRA at a rate of 1–5 ppm results in considerable lowering of pumping energy. To predict the capability of concerned polymer as a DRA we tried to give an effectiveness theoretical justification in terms of its chemical composition. It was shown that the most effective oil-soluble polymers relate to higher poly(1-alkenes) of superhigh molecular weight (M > 106). Additionally, the nature of the solvent is of importance. 1-Hexene polymerization in the presence of Zigler–Natta catalysts gives a super high molecular weight polymer which is the most effective drag reducer among the higher poly(1-alkenes). But if environment provide some limitation in poly(1-hexene) solubility, such as temperature lowering, or asphaltene content increasing the (co)polymers of 1-octene and 1-decene become the best. Для интенсификации перекачки нефти и нефтепродуктов по магистральным трубопроводам в настоящее время широко используют противотурбулентные присадки, при введении которых в турбулентный поток в предельно малой концентрации (C = 1–5 г/м3) наблюдается уменьшение энергетических затрат на транспортировку углеводородной жидкости. С целью прогнозирования перспективы промышленного использования присадки той или иной химической природы в настоящей работе представлено теоретическое обоснование и экспериментальное подтверждение эффективности различных полимеров. Установлено, что из всех нефтерастворимых полимеров наилучшими противотурбулентными свойствами обладают высшие поли-α-олефины со сверхвысокой молекулярной массой (Мr > 1·106). Также выявлено влияние компонентного состава и термодинамического качества растворителя на эффективность присадок, причем эти факторы следует рассматривать в совокупности. Например, цепь полимера, обогащенная гексеном, при прочих равных условиях синтеза имеет большую молекулярную массу, и такой полимер в хорошем растворителе снижает сопротивление лучше своих аналогов. Тем не менее, если превалируют факторы, ограничивающие растворимость полигексена (низкая температура, обилие асфальтенов в нефти), предпочтительными оказываются полимеры и сополимеры октена и децена, имеющие более низкую температуру стеклования.

Development of poly(ethyleneimine) grafted amphiphilic copolymers: Evaluation of their cytotoxicity and ability to complex DNA

Poly(ethyleneimine) (PEI) is one of the most widely used cationic polymers for gene delivery. The high molecular weight polymer, which is commercially available, is highly efficient but also very cytotoxic. The reduction in charge density by using nonlinear architectures based on low molecular weight (LMW) PEI is a promising approach to produce safer DNA-vectors. Herein, a group of cationic graft copolymers with different composition containing a hydrophobic biocompatible backbone and LMW linear PEI (lPEI) grafts obtained by ring opening polymerization and click chemistry was studied. The self-assembly and DNA complexation behavior of these materials was analyzed by the gel retardation assay, zeta potential measurements, and dynamic light scattering. The copolymers formed positively charged particles in water with average sizes between 270 and 377 nm. After they were added to DNA in serum-free medium, these particles acquired negative/near-neutral charges and increased in size depending on the N/P ratio. All copolymers showed reduced cytotoxicity compared to the 25 kDa lPEI used as reference, but the transfection efficiency was reduced. This result suggested that the cationic segments were too small to fully condense the DNA and promote cellular uptake, even with the use of several grafts and the introduction of hydrophobic domains. The trends found in this research showed that a higher degree of hydrophobicity and a higher grafting density can enhance the interaction between the copolymers and DNA. These trends could direct further structural modifications in the search for effective and safe vectors based on this polycation.

Surfactant-Polymer Formulations for EOR in High Temperature High Salinity Carbonate Reservoirs

Harsh conditions, such as high temperature (>100 oC) and high salinity (>50,000 ppm TDS), can make the application of chemical enhanced oil recovery (EOR) challenging by causing many surfactants and polymers to degrade. Carbonate reservoirs also tend to have higher concentrations of divalent cations as well as positive surface charges that contribute to chemical degradation and surfactant adsorption. The objective of this work is to develop a surfactant-polymer (SP) formulation that can be injected with available hard brine, achieve ultra-low IFT in these harsh conditions, and yield low surfactant retention. Phase behavior experiments were performed to identify effective SP formulations. A combination of anionic and zwitterionic surfactants, cosolvents, brine, and oil was implemented in these tests. High molecular weight polymer was used in conjunction with the surfactant to provide a high viscosity and stable displacement during the chemical flood. Effective surfactant formulations were determined and five chemical floods were performed to test the oil recovery potential. The first two floods were performed using sandpacks from ground Indiana limestone while the other three floods used Indiana limestone cores. The sandpack experiments showed high oil recovery proving the effectiveness of the formulations, but the oil recovery was lower in the cores due to complex pore structure. The surfactant retention was high in the sandpacks, but it was lower in Indiana Limestone cores (0.29-0.39 mg/gm of rock). About 0.4 PV of surfactant slug was enough to achieve the oil recovery. A preflush of sodium polyacrylate improved the oil recovery.

The Food Additive Xanthan Gum Drives Adaptation of the Human Gut Microbiota

The diets of industrialized countries reflect the increasing use of processed foods, often with the introduction of novel food additives. Xanthan gum is a complex polysaccharide with unique rheological properties that have established its use as a widespread stabilizer and thickening agent1. However, little is known about its direct interaction with the gut microbiota, which plays a central role in digestion of other, chemically-distinct dietary fiber polysaccharides. Here, we show that the ability to digest xanthan gum is surprisingly common in industrialized human gut microbiomes and appears to be contingent on the activity of a single bacterium that is a member of an uncultured bacterial genus in the family Ruminococcaceae. We used a combination of enrichment culture, multi-omics, and recombinant enzyme studies to identify and characterize a complete pathway in this uncultured bacterium for the degradation of xanthan gum. Our data reveal that this keystone degrader cleaves the xanthan gum backbone with a novel glycoside hydrolase family 5 (GH5) enzyme before processing the released oligosaccharides using additional enzymes. Surprisingly, some individuals harbor a Bacteroides species that is capable of consuming oligosaccharide products generated by the keystone Ruminococcaceae or a purified form of the GH5 enzyme. This Bacteroides symbiont is equipped with its own distinct enzymatic pathway to cross-feed on xanthan gum breakdown products, which still harbor the native linkage complexity in xanthan gum, but it cannot directly degrade the high molecular weight polymer. Thus, the introduction of a common food additive into the human diet in the past 50 years has promoted the establishment of a food chain involving at least two members of different phyla of gut bacteria.

PolyMaS: A new software to generate high molecular weight polymer macromolecules from repeating structural units

The Polymer Maker SMILES-based (PolyMaS) software was used to generate linear macromolecules from the repeating structural units (SRU) of polymers without limiting their length and molar mass. The SRU input is stored in the SMILES code available on the Internet. PolyMaS makes head-tail junctions to the desired length of the macromolecule.

The Food Additive Xanthan Gum Drives Adaptation of the Human Gut Microbiota

SummaryThe diets of industrialized countries reflect the increasing use of processed foods, often with the introduction of novel food additives. Xanthan gum is a complex polysaccharide with unique rheological properties that have established its use as a widespread stabilizer and thickening agent1. However, little is known about its direct interaction with the gut microbiota, which plays a central role in digestion of other, chemically-distinct dietary fiber polysaccharides. Here, we show that the ability to digest xanthan gum is surprisingly common in industrialized human gut microbiomes and appears to be contingent on the activity of a single bacterium that is a member of an uncultured bacterial genus in the family Ruminococcaceae. We used a combination of enrichment culture, multi-omics, and recombinant enzyme studies to identify and characterize a complete pathway in this uncultured bacterium for the degradation of xanthan gum. Our data reveal that this keystone degrader cleaves the xanthan gum backbone with a novel glycoside hydrolase family 5 (GH5) enzyme before processing the released oligosaccharides using additional enzymes. Surprisingly, some individuals harbor a Bacteroides species that is capable of consuming oligosaccharide products generated by the keystone Ruminococcaceae or a purified form of the GH5 enzyme. This Bacteroides symbiont is equipped with its own distinct enzymatic pathway to cross-feed on xanthan gum breakdown products, which still harbor the native linkage complexity in xanthan gum, but it cannot directly degrade the high molecular weight polymer. Thus, the introduction of a common food additive into the human diet in the past 50 years has promoted the establishment of a food chain involving at least two members of different phyla of gut bacteria.

Abstract P-38: Tunable Soft Networks of Wormlike Micelles and Clay Particles

Background: Over the past few decades, there has been a great deal of interest in the aqueous self-assembly of surfactant molecules into giant wormlike micelles (WLMs). These cylindrical aggregates undergo reversible breakdown processes and in favorable cases can grow up to few tens of micrometers that is comparable with the length of high molecular weight polymer. The viscoelastic properties of WLMs can be easily modified by different additives like salts or polymers. A new emerging research area consists of tuning the WLM solution properties by inorganic nanoparticles. It suggests, in particular, the use of networks of entangled WLMs as a matrix for producing soft nanocomposites with different kinds of embedded nanoparticles that are promising for controlled release, template synthesis, and oilfield applications. These materials can combine adaptive rheological properties of the WLM matrix and the functionality of nanofiller. Methods: Rheometry and cryo-transmission electron microscopy were combined to investigate the structure and properties of mixed WLMs of zwitterionic oleylamidopropyl dimethyl betaine and anionic sodium dodecyl sulfate surfactants and platelike particles of bentonite clay. Results: This system demonstrates the formation of giant linear long-lived WLMs, which even at extremely low surfactant concentrations reach a sufficient length to entangle with each other and form a temporally persistent network. The stability of these micelles can be due to electrostatic attraction between the headgroups of the anionic and zwitterionic surfactants and favorable volume/length hydrophobic ratio in the surfactant mixture. At increasing surfactant concentration, the long-lived linear micelles transform into fast-breaking branched micelles. Stable viscoelastic suspensions of clay particles in semi-dilute solutions of WLM were elaborated. They represent a novel type of soft nanocomposite with the tunable matrix. Structural studies revealed that the clay is dispersed in a dense network of entangled WLM in the form of 100-nm tactoids. Rheological investigations demonstrated that clay particles can induce an increase of viscosity and relaxation time by up to one order of magnitude. The effect of the clay becomes more pronounced with increasing content of anionic surfactant, when the micelles become branched. This behavior was explained by the stabilization of micelle-nanoclay junction points due to the screening of the repulsion between positively charged fragments of zwitterionic head groups by added anionic surfactant. Conclusion: The pronounced effect of nanoparticles on the viscoelasticity of the network formed by branched WLMs was observed for the first time. The nanoparticles-WLM junctions were confirmed by cryo-TEM data. The elaborated systems are of interest for many industrial applications.

Probing the Release of Bupropion and Naltrexone Hydrochloride Salts from Biopolymeric Matrices of Diverse Chemical Structures

In the last decades, the notion of including excipients in the formulations, as inert substances aiding production processes, has changed and they are recently viewed as multifunctional discrete entities. It is now well documented that excipients serve several roles, spreading from the stabilization and modified release, to providing biocompatible properties and targeting moieties. The aim of this study was to develop matrix-based oral drug delivery systems of bupropion hydrochloride (BUP·HCl) and naltrexone hydrochloride (NTX·HCl), suitable for releasing these active substances in a modified manner, providing a stable level of drug release, which is simultaneously therapeutically effective and non-toxic, thus reducing side effects, after a single dose administration, throughout the gastrointestinal tract. The new formulations, employing hydroxypropylmethycellulose (HPMC K15M) (a cellulosic polymer, which, generally hydrates to form a gelatinous layer that is critical to prevent wetting and rapid drug release from the matrices), poly(methacylic acid-co-ethyl acrylate) 1:1 (Eudragit® L100-55: effective for site specific drug delivery in intestine), poly(ethylene oxide) (PEO) (7 × 106: a high molecular weight polymer, water-soluble, in micro-granular powder form), as the rate controlling polymers, were chosen to lead to a “soothing out” release pattern of these drugs, at 0 ≤ t ≤ 120 min. Moreover, the release of the two drugs from the ulvan-based tablets, was found to follow the desired profile, throughout the entire course of the dissolution experiments.

Badania procesu żelowania zaczynów cementowych przeznaczonych do uszczelniania otworów przewiercających płytkie poziomy gazonośne

The article presents issues related to the sealing slurry technology concerning gelling processes (i.e., static built-up of gel strength of cement slurries). Based on research conducted around the world, it can be concluded that the rate of gelling of the cement slurry has an important role in the process of preventing possible gas exhalations from the annular space. After the cement slurry is pumped into the borehole (especially in zones with shallow gas horizons), the so-called migration (exhalation) of the formation medium (i.e. uncontrolled outflow of e.g. gas from the annular space) may occur. The most important caused of gas migration from the shallow horizons after casings cementation are the inability to maintain a certain overpressure by the column of the binding cement slurry and too long binding of the cement slurry after pumping into the borehole. The initially liquid cement slurry, when pumped out of the casing, acts as a liquid, creating a certain hydrostatic pressure on the deposit. e.g. gas. However, after some time, the period of building the static gel strength (SGS) starts until the cement sets. The SGS building process, i.e. gelling of the cement slurry, reduces the ability to transmit hydrostatic pressure to the reservoir. The Oil and Gas Institute – National Research Institute has tested a number of cement slurry formulations characterized by different gelling and bonding times. Slurries were made on the basis of three typed of latex with the symbols L1, L2, L3, two types of water glass with symbols S1, S2, amorphous silica with the symbol CB, nano-components based on n-SiO2 and n-Al2O3 with the symbols NS and NA as well as high-molecular weight polymer with the symbol GS. Different amounts of setting accelerator were used with the tested slurries. Tests were carried out for eighteen cement recipes, which made it possible to select the optimal compositions of slurries with short gelling and setting times. The samples containing one of the types of latex in the appropriate concentration, the GS polymer, as well as those containing n-SiO2 and n-Al2O3, showed a very advantageous course of the gelation plot (static build-up of gel strength). Their TT transition times, reflecting the course of gelation, ranged from several to several tens of minutes (which is a proof of high ability to prevent gas migration from shallow gas accumulations). The cement slurries developed at the Oil and Gas Institute – National Research Institute, due to their good technological parameters, could be used in the process of cementing casing strings.