Mechanism and gelling effects of linked polymer solution in the core

By using Bush viscometer, dynamic and static laser scatter instrument, scanning electron microscope and core flow experimental apparatus, experiments were conducted to study the viscosity, molecular coil dimensions, molecular configuration and static gelation of amphoteric polymer solution and linked amphoteric polymer solution in porous media and affecting factors, and to analyze the gelation mechanism of linked polymer solution in the core. The results showed that with the increase of solvent water salinity, the cross-linking reaction rate increases; with increase of aging time, the gelling effect gets stronger and stable; with the increase of shear time, the lineation of polymer molecules gets more obvious, the gelling effect in pores gets worse; under the condition of low permeability, the cross-linking reaction mainly is intramolecule cross-linking; with the increase of core permeability, i.e. the increase of pore size, the gelling effect gets better in the core, and inter-molecular cross linking reaction is more likely to take place. The experimental data and theoretical analysis showed that in the linked amphoteric polymer solution, the cross-linking reaction occurs between the different branched-chain of the same molecule firstly (intra-molecular cross-linking), then the cross-linking reaction extends to different polymer molecules (i.e. inter-molecular cross-linking).