Preparação de hidrogéis nanocompósitos à base de poliacrilamida (PAM) e polietilenoimina (PEI) para recuperação avançada de petróleo

Abstract

In this work, polyacrylamide (PAM) nanocomposites hydrogels were obtained in saline solutions with ionic strength μ = 0.6 from the incorporation of 0,5; 1,0 and 2,0% (w/w) of TiO2 nanoparticles (NPs), oxidized carbon nanotubes (CNT-ox) and graphene oxide (GO) for application in conformity control of oil reservoirs. The nanocomposites hydrogels were prepared using polyethyleneimine (PEI) as a crosslinking agent in the formation of the three-dimensional structure of the gel and the influence of the mass proportion of polymer and crosslinker was analyzed by varying the amount of PEI in the systems, making it possible to determine most promising systems for incorporation of nanofillers. Dynamic rheology measurements showed that the TiO2 nanoparticles provide a structural reinforcement to the gel from a double crosslink, increasing the elastic character for the hydrogels obtained in the proportion PAM/PEI 9:2 (m/m), promoting greater thermal stability and increasing the time required for gelation; and reaching the maximum gel force (J) without loss of stability in the proportion PAM/PEI 9:4 (m/m). CNTox nanocomposite hydrogels promoted greater stability of the gel force and reduced up to 56% the percentage of syneresis in relation to conventional hydrogels for the gel obtained in the mass ratio 9:3 (PAM/PEI). The incorporation of GO provided an increase in gelation time of up to 72 hours, keeping the gel-force I stable throughout the production for the sample obtained from the PAM/PEI 9:3 (m/m) ratio. In addition, all hydrogels with GO incorporation proved to be extremely efficient in reducing water loss, presenting a decrease in syneresis of up to 78%. In general, the results showed that nanocomposites hydrogels with 1.0% incorporation of carbon nanomaterials and TiO2 NPs are promising for improving conformance control by blocking preference zones in oil reservoirs.