Исследование фильтрационных и реологических свойств полимерного геля для повышения нефтеотдачи пластов

Abstract

The relevance. Polymer flooding is widely used in practice in the development of oil fields. The high-concentration polymer solution has strong viscoelasticity, but with the increase in mass concentration of the polymer, the compatibility problem occurs between polymer molecules aggregate size and reservoir rock pore size during its practical application. Cr3 + polymer gel based on intramolecular cross-linking has a smaller aggregate size and good compatibility with the reservoir, so it is relevant to study the effect of gel formation of Cr3 + polymer gel and its influence factors.\xa0The main aim of the research is to study filtration and rheological properties of polyacrylamide-based aqueous gel with chromium acetate to enhance oil recovery.\xa0Methods: physical simulation of oil displacement and fluid filtration under reservoir conditions on a filtration unit, determination of viscosity of cross-linked polymer gel using the Brookfield DV-II viscometer, measuring the size of the molecular coil Dh in a Brookhaven BI-200SM light scattering system (Brookhaven Instruments Cop., USA), determination of viscoelasticity using the Harke10 rheometer.\xa0Results. Regulating the concentration of polymer, water solution salinity and the ratio of the polymer content and chromium (w(П/Cr3+)), one can obtain the Cr3+ polymer gel system based on intramolecular cross-linking with a smaller molecular aggregate and higher resistance confidence. After the reaction of intramolecular cross-linking of the polymer solution, on the one hand the viscoelasticity of the system is significantly improved and the oil displacement coefficient increased. On the other hand, the intramolecular crosslinking reaction reduces the flexibility of the polymer molecule aggregates, increases their rigidity, weaken their deformability in the process of passing through the pores, and enhance the retention ability in the high permeability layer. Cr3 + polymer gel system not only has good injectability, it can also gradually reach a higher injection pressure, so it enlarges sweep volume effectively. In total, it is shown that the oil recovery coefficient of the polymer gel system is higher than the polymer solution.