Development Of A Hydrophobically Associating Relative Permeability Modifier System

Using N,N-dimethylaminoethylmethacrylate (DMAEMA) and methoxy polyethylene glycol methacrylate (MPEGMA) as monomers, the main agent of hydrophobically associating relative permeability modifier system(RPMS) was prepared through inverse emulsion polymerization, hydrolysis. Finally, a hydrophobically associating RPMS was developed. The details were as follows:Using AIBA and NaHSO₃-(NH₄)₂S₂O₈ as initiators, hydrophobically associating copolymer was synthesized by inverse emulsion polymerization. The effects of monomer ratio, emulsifier concentration, initiators concentration, amount of Na₂EDTA, pH of aqueous phase, reaction time and reaction temperature on the intrinsic viscosity of polymer and the convert ratio of the polymerization were studied. Finally, the optimal reaction conditions of this experiment were as follows: monomer feed ratio (DMAEMA:MPEGMA) is 5.7:1, concentration of emulsifier is 7.8%, concentration of initiators is 0.6%, amount of Na2EDTA is 0.08%, pH of aqueous-phase is 8.5, time of polymerization is 5h, temperature of polymerization is 30℃. In these conditions, the convert ratio reaches 52.42% and the intrinsic viscosity reaches 212.66ml/g. It was structurally confirmed by FT-IR. The reactivity ratios of the copolymer were obtained by the Fineman-Ross method. The results show that the reactivity ratios of DMAEMA and MPEGMA are r¹=0.32, r²=1.52. Furthermore, the effects of its concentration, temperature, shear rate, shear recovery, shear time and salt on the apparent viscosity of copolymer aqueous solution were investigated. We also researched its adsorbability. The results reveal that the copolymer solution has critical association concentration, is suitable for 50℃and has better adsorbability, salt and shearing resistance.Choosing partially hydrolyzed polymer of the copolymer as the main agent of hydrophobically associating RPM system, its adsorbability on the oil sandstone is investigated, that is to say, the equilibrium concentration is approximately 5100 mg/L while the saturated adsorption is about 0.652 mg/g. Cross linker concentration, salt, pH and temperature also have effects of RPMS. The results show that the system is suitable for pH 7, the formation temperature of 45℃,and has preferable salt tolerance. Finally, the residual resistance factors to water and oil were measured by core displacement test. The residual resistance factor to water is found to 29.8 while that to oil is 1.5.