Preparation And Properties Of Polyurethane / Vermiculite Composite Sealing Agent

With the development of heavy oil reservoir, steam stimulation induced steam channeling which affect the production of heavy oil and recovery directly. So it is very important that we must to study the composite plugging agent to plug the steam channeling Polyurethane/silicate composites are widely used recently. Polyurethane (PU) is a kind of polymer, which has excellent comprehensive performance and is widely used in petroleum, coal and other industries. Addition of inorganic vermiculite into the PU is the important methods to improve the heat resistance and mechanical properties of PU. Polyimide is a kind of heat resistant performance of polymer compound, the introduction of imide chain structure can improve the heat resistance of polyurethane.In the experiment, long-chain quaternary alkyl ammonium salts was used to modified the vermiculite, the best result is that vermiculite (VMT) was modified by cation exchange with octadecyl trimethyl ammonium bromide (OTAB) as precursor (OVMT), the OVMT were dispersed well in polycarbonate polyol (PCDL) with the method of high speed stirring and ultrasonic dispersion as soft segment of PU, two phenyl methane diisocyanate (MDI) and1,4-cyclohexane diisocyanate (CHDI) as hard segment, and the introduction of pyromellitic dianhydride (PMDA), three series of polyurethane/organic vermiculite composite plugging agent (PUMPB/OVMT, PUCPB/OVMT and PUCPPB/OVMT were prepared by the method of polymerization. The best synthetic conditions of polyurethane prebody have optimized and the influence of the properties of composite plugging agent also have researched.The performance of the composite plugging agent was discussed. The results show that the mechanical properties of the PUCPB/OVMT composite plugging agent is obviously enhanced, especially the tensile strength was26.8MPa and the elongation at break was443%, which increased52.3%and31.5%than PUCPB, respectively. There is no weight loss for composite plugging agent when the temperature is200℃, the loss rate of PUCPB/OVMT is only0.84%in300℃, which shows that the composite plugging agent has excellent thermal stability. The plugging rate of composite plugging agent is over90%with good plugging ability. The bibulous rate of composite plugging agent is around5.0%in solution of salt, which has better toughness and salt-resistant ability. The structure of OVMT was characterized by the FT-IR, XRD, TGA and SEM. The results show that the layer spacing of OVMT increased to2.37nm and further enlarged to2.92nm by the loading of PCDL, which verified the effect of modification of vermiculite by the methods of TGA and SEM.