Viscoelastic displacement and anomalously enhanced oil recovery of a novel star-like amphiphilic polyacrylamide

Design of novel temperature-resistant and salt-tolerant acrylamide-based copolymers by aqueous dispersion polymerization

Development of polymer-based flooding technology to improve oil recovery efficiency, water dispersion copolymerization of acrylamide, cationic monomer methacryloxyethyltrimethyl ammonium chloride (METAC), and anionic monomer acrylic acid (AA) were carried out in aqueous ammonium sulfate solution with polyvinyl pyrrolidone (PVP) as the stabilizer. The copolymers were characterized by ¹H-NMR, FT-IR, TG, and SEM to confirm that they were prepared successfully and exhibited excellent salt-resistant property. Moreover, the effect of the aqueous solution of ammonium sulfate (AS) concentration, stabilizer concentration, and initiator concentration on the viscosity and size were systematically investigated. To further improve the thermal endurance properties of copolymer, hydrophobic monomers with different alkyl chain lengths were added to the above system. The acrylamide-based quadripolymer possessed prominent thermal and salt endurance properties by utilizing the advantages of zwitterionic structure and hydrophobic monomer. With the temperature rising, the viscosity retention could reach 70.2% in the water and 63.8% in the saline. This work had expected to provide a new strategy to design polymers with excellent salinity tolerance and thermal-resistance performances.

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.