Salt resistance study and molecular dynamics simulation of hydrophobic-association polymer with internal salt structure

Abstract

The salt resistance of hydrophobically relating polymer fracturing fluid is one of the main indicators to meet the fracturing operation. Thus, a chain transfer agent was created in this study. Hydrophobically related polymer PDMA2 was synthesized in an aqueous solution through the RAFT approach. The salt resistance mechanism of the polymer was elucidated using molecular simulation software. The experimental results demonstrated that the salt resistance of the polymer can be enhanced by introducing long hydrophobic chain monomers via RAFT polymerization. Inorganic salt ions can improve the polymer skeleton and facilitate polymer chain bonding. The rotation radius of the hydrophobic polymer PDMA2 lowers as the salt concentration rises, allowing polymer molecule interaction. Combined with spatial conformation and fluorescence spectrum analysis, PDMA2 containing hydrophobic monomer was discovered to improve the association effect of polymer and produce more hydrophobic microregions. The radial distribution function results show that increasing the salt content compresses the polymer's main chain. On the polymer backbone, the radial distribution function between N-N atoms grows. This study demonstrates that the hydrophobic-association polymer can meet the service conditions of oilfield mineralized strata and lower the consumption of freshwater resources.