Molecular Dynamics Simulation And Experimental Study Of Silica/polyacrylamide-acrylic Core-shell Microspheres

Inorganic-Organic composite has integrated advantages of inorganic matters and organic matters, such as elasticity, good heat resistance and high strength. Inorganic/polymer composite microsphere plugging agent can be injected into the formation well and it is stable in the special bad oilfield environment. It can carry out the in-depth profile control water plugging effect step by step through its deformation under certain pressure. The composite microsphere has moderate plugging strength and can keep good expansibility. It improve the heat resistance, impact resistance and shear resistance of traditional water plugging polymer microspheres. In addition, their particle size transform from nanoscale to microscale, which is a kind of broad potential of oil field profile control water plugging agent. Due to the complicated structural properties of this composite microsphere, lots of quantitative relationships are still missing through traditional experiment method. In the era of rapid development of computer technology, computer simulation technology was a reliable mean of research on composite materials in recent years for it can further understand it from the microscopic view.In this paper, molecular dynamics simulation method combined with experiments was applied to study some properties of this microsphere.First, the interface formed by acrylamide acrylicacid copolymer PAMAA and silica modified by four modifier was studied in vacuum and aqueous environment, results show that silica modified by vinyl ethoxy silane has a good interaction with copolymer and water has an influence on the interaction between copolymer and modified silica surface. Second, on different temperature, structural properties of microsphere in water and four surfactant solutions were studied. Results show that addition of DTAB, SDS, DTAB and AEO have an effect on the size of microsphere. And the microsphere size became smaller with increase of temperature. Third, the swelling performance of crosslinked microsphere in different temperature was studied, results show that temperature has an effect on the free volume of crosslinked microsphere. Finally, composite microspheres was synthesized by inverse micro emulsion polymerization and their article size distribution and thermostability were evaluated. Thermal stability analysis shows that the microsphere formed by silica modified by vinyl ethoxy silane shows the best thermostability performance. The results obtained by experiment was consistent with the simulation results. And the particle size distribution results show that microsphere article size in above three surfactant solution are bigger than that in pure water and show wider particle size distribution. This result also has a good consistency with the ROG of microsphere obtained by simulation. Simulation results have been verified by experiment results.