Residual Polymer And The Nature Of The Demulsifiers On Oil-water Interface Impact Study

Although the effect of polymer flooding technology, but the produced fluid processing, due to the existence of output polymer, has become a troubled oil field production and did not fundamentally solve the problem. Polymer exacerbated emulsion stability and the efficacy of existing demulsifier drop these two problem as a starting point in this article, emphasis from the microscopic study of interfacial dilational viscoelasticity of the partially hydrolyzed polyacrylamide and demulsifier to identify the mechanism of polymer and demulsifier at the interface provides a theoretical and experimental basis in order to reduce processing difficulty containing polyethylene emulsion in this article.(1) By infrared spectroscopy and elemental analysis of the various components of the LD crude oil, the results show that present in the resin and asphaltene, the absorption peak of the nitrogen compounds, the complex structuce; resin and asphaltene contain a higher content of heteroatoms, H/C ratio of small to large order:asphaltene, resin and aromatics, saturates. Infrared analysis and elemental composition results show that the active component in the crude oil present in the resin and asphaltene.(2) The interfacial tension experiments showed that the partially hydrolyzed polyacrylamide allows oil-water interface tension y rised, and with time, containing polymer system interfacial tension gradually reduced and eventually stabilize.(3) When the HPAM at the interface time within0-4h, the interfacial dilational modulus|ε|from1.8mN/m to4.5mN/m, the role of the HPAM on the oil-water interface is enhanced over time. Containing HPAM system, the dilational modulus|ε|, dilational elasticity εd with the increase in vibration frequency is increased, expansion viscosity ηd is reduced with increasing frequency and by logω-log|ε|the slope of the curve shows that the HPAM in the oil-water interface is not a simple diffusion relaxation. When HPAM concentration of25mg/L, the|ε|, εd, y ηd are to minize, interfacial film strength is weak. HPAM concentration>50mg/L, three types of interface parameters gradually increase, the strength of the interfacial film increases. HPAM molecular weight increased from260.000to9.6million of the process, three expansion parameter|ε|, εd, ηd trend is increased first and then stabilized and finally continue to increase.(4) When the polymer degree of hydrolysis increases, interfacial dilational modulus all decrease under different frequencies; the greater the HPAM hydrophobic monomer content, the dilational modulus|ε|the greater, the more stable interfacial film.Containing HPAM system, the salt content in the0to1800mg/L, with the increase of salt content,|ε|is lower, salt content rose to1800mg/L, with the increase of salt content,|ε|increase slightly. In the surfactant system, surface active agent concentration is low, the addition of HPAM significantly such that|ε|to reduce; surfactant concentration is high, the polymer can significantly increase of|ε|.(5) Straight-chain demulsifier to reduce containing polyethylene oil-water interfacial tension to12mN/m or so within10min. the branched-chain demulsifier to reduce the interfacial tension to about16mN/m within20min. the small molecule demulsifier need40min to the interfacial tension dropped to24mN/m. When the three demulsifier molecules in concentrations close to cmc. the interfacial adsorption saturation, the interfacial tension to reach equilibrium.(6) Straight-chain demulsifier at role90min when to reduce containing polyethylene water interfacial dilational modulus and eventually maintained at about2.5mN/m, branched-chain demulsifier at role140min when to reduce the interfacial dilational and eventually maintained at about3.5mN/m, while the time required of small molecules demulsifier is more than three or four hours, and dilational modulus of in4.8mN/m.(7) Demulsifiers of different concentrations and different measurement frequencies, the straight-chain demulsifier in the oil-water interface more efficient than the branched-chain demulsifier. Because the straight-chain demulsifier PO content is higher than the branched-chain, so that it can rely on ether bonds with water to form hydrogen bonds and though this attractive and surfactants to replace HPAM adsorption at the interface and natual active substances, with the demulsifier adsorption at the interface increases the interfacial dilational modulus decreased, resulting in membrane intensity. Branched-chain demulsifier, its PO content ratio is small, medium containing polymer oil and water soluble in the continuous phase aqueous phase capacity is better, need to experience from the aqueous phase to the diffusion of the oil phase redistribution to oil-water interface.(8) Found through experiments, the best straight-chain demulsifer, reduce the interfacial tension and interfacial dilational viscoelasticity the ability of the strongest. Although the branched-chain demulsifier similar to the role in the results and the straight-chain demulsifier. But the demulsification effect than the straight-chain demulsifier slightly, followed by small molecules demulsifiers reduce the interfacial tension and interfacial viscoelastic worst.