Amphiphilic copolymers based on PEG-acrylate as surface active water viscosifiers: Towards new potential systems for enhanced oil recovery

Synthesis and Performance Evaluation of an Organic/Inorganic Composite Gel Plugging System for Offshore Oilfields

In this article, we developed a new composite gel for plugging dominant fluid flow channels in offshore oilfields. The composite gel was synthesized by organic and inorganic gel networks interpenetrating into a compact three-dimensional spatial network structure, resulting in a good plugging effect. The performance of the composite gel was evaluated from the aspects of gelling characteristics and gel microstructure, while the plugging effect was evaluated through core experiments. The results showed that the influencing order of each component on gelling was acrylamide > cross-linking agent > urea > initiator > polyaluminum chloride. The initial viscosity of the composite gel was about 5-6 mPa·s, and it had good plugging abilities in different permeability cores. In comparison with inorganic gels (plugging ratio of 77.2%) or organic gels (84.8%), the composite gel system has a plugging ratio of up to 99.5% using a core with water permeability of 4300 mD. Besides, the reservoir applicability of the composite gel was studied, and the results suggested that the composite gel system had good resistance to dilution, mechanical shear, oil corrosion, and aging and could be quickly removed after plugging.

Micellar drug delivery vehicles formed from amphiphilic block copolymers bearing photo-cross-linkable cyclopentenone side groups

UV core cross-linkable amphiphilic block copolymers containing cyclopentenone side groups on the hydrophobic backbone were synthesized and drug delivery experiments were done with the cancer therapeutic drug Doxorubicin.

pH-Responsive Polyketone/5,10,15,20-Tetrakis-(Sulfonatophenyl)Porphyrin Supramolecular Submicron Colloidal Structures

In this work, we prepared color-changing colloids by using the electrostatic self-assembly approach. The supramolecular structures are composed of a pH-responsive polymeric surfactant and the water-soluble porphyrin 5,10,15,20-tetrakis-(sulfonatophenyl)porphyrin (TPPS). The pH-responsive surfactant polymer was achieved by the chemical modification of an alternating aliphatic polyketone (PK) via the Paal–Knorr reaction with N-(2-hydroxyethyl)ethylenediamine (HEDA). The resulting polymer/dye supramolecular systems form colloids at the submicron level displaying negative zeta potential at neutral and basic pH, and, at acidic pH, flocculation is observed. Remarkably, the colloids showed a gradual color change from green to pinky-red due to the protonation/deprotonation process of TPPS from pH 2 to pH 12, revealing different aggregation behavior.

The Reservoir Adaptability and Oil Displacement Mechanism of Polymer Microspheres

Polymer microsphere profile control is a promising approach for the profile control of heterogeneous reservoirs. Matching between polymer microspheres and the reservoir pore throat is crucial for profile control. In this study, the range of the optimal matching factor Ra between polymer microspheres and core porosity was divided through core permeability limit experiments, and the dynamic migration laws and shut-off patterns of microspheres were studied using 9-m-long cores and microscopic models. The oil displacement effect and mechanism of microspheres were analyzed using three cores in parallel. The "injectability limit" and "in-depth migration limit" curves were divided by Ra into three zones: blockage (Ra < 1.09 ± 0.10), near-well profile control (1.09 ± 0.10 < Ra < 5.70 ± 0.64), and in-depth fluid diversion (Ra > 5.70 ± 0.64). During migration in porous media, the microspheres gradually enlarged in size and thus successively shut off in four forms: multi-microsphere bridging shut-off, few-microsphere bridging shut-off, single-microsphere shut-off, and elastic shut-off. Microspheres with a rational combination of sizes versus those with a single particle size further enhanced reservoir oil recovery under certain reservoir conditions. Through "temporary shut-off-breakthrough-temporary shut-off," the polymer microspheres were able to change the fluid flow rate and streamlines, mobilize residual oils, and enhance the oil recovery rates.

The effect of macromolecular structure on the rheology and surface properties of amphiphilic random polystyrene-r-poly(meth)acrylate copolymers prepared by RDRP

In this work rheological and surface properties of various random copolymers of styrene and sodium (meth)acrylate, prepared using reversible deactivation radical polymerization (RDRP), were studied. It is shown that the properties of these polymers in water solution, relevant for several applications, are affected by their chemical structure and molecular weight. Cryo-TEM images of their concentrated water solutions do not show the presence of nano-objects as micelles, however the existence of some aggregates seems to be confirmed by fluorescence measurements using pyrene as a hydrophobic probe and by surface tension measurements. Moreover, interesting results are displayed about the viscosity as well as the surface tension of these water polymer solutions, due probably to different interactions at the molecular level as suggested by fluorescence measurements.

Solution properties and aggregating structures for a fluorine-containing polymeric surfactant with a poly(ethylene oxide) macro-monomer

A polymeric surfactant (PFSA) was synthesized by the aqueous free-radical copolymerization using acrylamide, sodium 2-acrylamido-2-methylpropane sulfonate, allyl-capped octylphenoxy poly(ethylene oxide) (PEO) with the polymerization degree of 20 (AOP) and 1H,1H,2H,2H-perfluoro-1-decyl p-vinylbenzyl ether (VF). PFSA exhibited both the good surface and interfacial activities and the thickening behaviour. It could be used in enhanced oil recovery to increase both sweep and oil displacement efficiencies. The critical micelle concentration (CMC) of PFSA was 0.1 g l-1 in aqueous solution. The spherical micelles with the diameter of 100 nm were formed at CMC, and numerous compact worm-shaped micelles were observed above CMC. The interfacial tension was 0.027 mN m-1 for the 0.1 g l-1 PFSA solution containing 5 g l-1 NaCl and 0.209 g l-1 SDBS. The PFSA solutions still showed low interfacial tensions at high NaCl concentrations and temperatures, respectively, because of the incorporation of both VF and AOP containing long PEO.

Design and Study of a Novel Thermal-Resistant and Shear-Stable Amphoteric Polyacrylamide in High-Salinity Solution

Abstract: Water-soluble polymers are widely used in oilfields. The rheological behaviors of these polymers in high-salinity solution are very important for stimulation of high-salinity reservoirs. In this work, a novel thermal-resistant and shear-stable amphoteric polyacrylamide (PASD), prepared from acrylamide (AM), sodium styrene sulfonate (SSS), and acryloxyethyl trimethylammonium chloride (DAC) monomers, was prepared by free-radical polymerization in high-salinity solution. The amphoteric polyacrylamide was characterized by Fourier transform infrared (FTIR) spectroscopy, nuclear magnetic resonance spectroscopy (¹H NMR), elemental analysis, thermogravimetric analysis (TG), and scanning electron microscopy (SEM). The amphoteric polyacrylamide exhibited excellent salinity tolerance. The slow increase in apparent viscosity of the polymer with increase in salinity was interesting. The amphoteric polyacrylamide showed perfect temperature resistance in high-salinity solution. The viscosity retention reached 38.9% at 120 °C and was restored to 87.8% of its initial viscosity when temperature was decreased to room temperature. The retention ratio of apparent viscosity reached 49.7% at 170 s^-1 and could still retain it at 25.8% at 1000 s^-1. All these results demonstrated that PASD had excellent thermal-resistance and shear-stability in high-salinity solution. We expect that this work could provide a new strategy to design polymers with excellent salinity-tolerance, thermal-resistance, and shear-stability performances.