Study On The Performance Evaluation And Mechanism Of Hydrophobic Associated Polymer Complex System With Different Molecular Structures

Hydrophobically modified polyacrylamide (HMPAM) has good viscoelasticity and shear resistance, so it has broad application prospects in the field of polymer flooding enhanced oil recovery. However, polymer oil displacement agent effective viscosity decreased greatly in the harsh environmental conditions of the reservoir with high temperature and high salinity, etc. To solve this problem, in this paper, two kinds of significant synergistic effect of composite system had been got by mixing different molecular structure of HMPAM, and further study of the factors affecting synergy. Finally, we discuss the mechanism of the synergistic effect by rheology and fluorescence spectroscopy. This article main research content is as follows:(1) Through thermal polymerization, AM/C16DMAAC copolymer was syntheticed by acrylamide(AM) and cetyl dimethyl ammonium chloride (C16DMAAC), and then hydrolyzation with sodium hydroxide, three hydrophobically modified polyacrylamide P(AM/NaAA/C16DMAAC) of different hydrophobic group content were got, and hydrophobic group content were0.2mol%,0.5mol%,1.0mol%——PA series. Three hydrophobically modified polyacrylamide P(AM/DMC/C16DMAAC) with different cationic degrees were syntheticed by AM,75%methy acryloyl oxygen ethyl trimethyl ammonium chloride(DMC) and C16DMAAC, and cationic degrees were1.0mol%,3.0mol%,5.0mol%--—PB series. Through light polymerization, AM/NaAMC14S copolymer was syntheticed by AM and2-acrylamide fourteen alkyl sulfonate(NaAMC14S), and then hydrolyzation with sodium hydroxide, three hydrophobically modified polyacrylamide P(AM/NaAA/NaAMC14S) of different hydrophobic group content were got, and hydrophobic group content were0.05mol%,0.10mol%,0.15mol%——PC series. The structure of PA, PB and PC were characterized by infrared spectrum(FT-IR) and nuclear magnetic resonance hydrogen spectrum(’HNMR), proved synthetic polymers were target polymers. Intrinsic viscosity of HMPAM was measuremented with the solvent of0.2mol/L sodium chloride and50%volume of formamide, and then calculate their molecular weight.(2) Polymer PA and PB were blended to form an composite system, we studied the influence law of synergistic thickening effect between them by complex ratio, cationic degrees, salinity, polymer concentration, temperature and shear rate. The density and strength of junction of composite solution network structure were higher than single polymer solution by studying synergy mechanism between PA and PB through rheology test. The number of hydrophobic microdomain of composite solution was higher than single polymer solution by studying synergy mechanism between PA and PB through fluorescence spectrometry. The reasons for synergistic effect between polymers were that composite system network structure became stronger and more dense.(3) Polymer PA and PC were blended to form an composite system, we studied the influence law of synergistic thickening effect between them by complex ratio, content of the hydrophobic monomer C16DMAAC, content of the hydrophobic monomer NaAMC14S, salinity, polymer concentration, temperature and shear rate. The density and strength of junction of composite solution network structure were higher than single polymer solution by studying synergy mechanism between PA and PC through rheology test. The number of hydrophobic microdomain of composite solution was higher than single polymer solution by studying synergy mechanism between PA and PC through fluorescence spectrometry. The reasons for synergistic effect between polymers were that composite system network structure became stronger and more dense.(4) Comparing oil displacement efficiency of composite system with single polymer solution by platform for flat sand inclusion of physical model, the results show that oil displacement efficiency of composite system was neraly at least10%higher than that of single polymer solution, up to30%. Proved that composite system had practical application value.