Seepage characteristics and mechanism of Cr~(3+) cross-linked polymer solution in ultra-high salinity media

A new type of Cr3 +cross-linked polymer solution with good salt resistance was developed due to the demand of deep fluid diversion technique in the ultra-high salinity reservoir.Bush viscometer,dynamic light scattering,rheometer and core flow experimental device were used to characterize this solution.The influences of mineralization on the viscosity of the Cr3 +polymer solution,molecular coil dimensions,viscoelasticity and flow characteristics were investigated.The results show that compared with the polymer solution,the viscosity of Cr3 +polymer solution decreases slightly,the molecular coil dimensions of Cr3 +polymer solution increase slightly,the viscoelasticity of Cr3 +polymer solution increases,and the drag coefficient and residual resistance coefficient of Cr3 +polymer solution significantly increases.When the preheating time is shorter,the drag coefficient and residual resistance coefficient of Cr3 +polymer solution gradually increase with the increase of salinity.However,when the preheating time becomes long,the drag coefficient and residual resistance coefficient of Cr3 +polymer solution gradually decrease with the increase of salinity.In the Cr3 +cross-linked polymer solution,the cross-linked reaction preferably occurrs between the different branched-chain of the same molecule,i.e.intra-molecular cross-linked,then the cross-linked reaction extends to the different polymer molecular,i.e.inter-molecular cross-linked,and form regional dictyoaggregate state.