Preparation Of Microgel Applied In Recovery Enhancement

Microgel, which generates mainly in the form of polymer intermolecular crosslink by a certain crosslink technology, is a kind of polymer gel dispersing medium. The microgel can overcome the crosslink uncontrollable disadvantage of the common gel plugging agents used in field. It has advantages of deep shutoff, high selectivity, insensibility to the physical chemical condition under ground, controlled particle diameter, good stability and so on.Under steady shear conditions, Chrome crosslink system was studied by rheology instrument (HAAKE RS150) in this paper, obtaining the kinetics equation of crosslink reaction. Compared with the statical crosslink, the crosslink reaction carries on more easily and the polymer concentration has more dramatic effects on the gel time during the crosslink under the shearing condition. The crosslink process under steady shear can be divided into four stages obviously: induction stage, gelation stage, size-limited stage and stable stage. With the increase of the shear rate, these four stages become more and more indistinct.The microgel was prepared through shear and crosslink by peristaltic pump and was characterized by inherent viscosity, particle diameter and apparent viscosity. The results indicates that the inherent viscosity and particle diameter determined by dynamic light scattering are greatly affected by the polymer concentration, the microgel particles present stylolitic, streaky and leiosphere shapes, and the microgel has better shear stability, thermal stability and salt-resistance.The application of the microgel was also studied by flow experiments. The results demonstrate that the microgel with excellent injectivity can plug off water in depth and has obvious decreasing effect selectively to the oil and water phase permeability, which can enhance the oil recovery precipitously.