Polyacrylamide and its derivatives for oil recovery

Figure 5. 
Schematic of AMVPPS copolymer conformations in aqueous NaCl solution. 
[151]
 

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The copolymer in solution showed good viscosity building performance due to 
electrostatic associative interactions despite the presence of salt. For thermo-stability, 
TGA and DTA tests demonstrated that as the VPPS content was increased from 0-to 
10mol.-% in the copolymer, the decomposition temperature of the copolymer was 
improved from 263to 388°C). With regard to thickening ability, the zwitterionic 
copolymer tended to form cyclic or head-to-tail structures, as shown in Figure 5 
Gaillard, et al.[146] evaluated anionic co- and terpolymers of AM monomer in lab 
scale EOR performance. Results showed that polymer flooding could be successful in 
reservoirs with relative high temperature and poor water quality (in presence of oxygen, 
iron, and radical; under 90-120 °C). Theco- or terpolymers were synthesized from AM, 
sodium acrylamide-tertiary-butyl sulfonate (ATBS), and NVP monomers. The viscosity 
of polymer solutions aged up to 120 °C could typically retain 60 to110% of their initial 
viscosity after a few months compared to a 10 to 40% viscosity retention of conventional 
PAM systems. At 100°C, the viscosity of the polymer solution was stable for over 60 
days in the presence of 200 ppb of oxygen. At 120°C, radical degradation resulted, to 
cause a viscosity drop of the solution. 
Aparecida de Melo, et al.[153] presented the application of polyelectrolytes with 
negative charge in the oilfields of Carmopolis, Buracica, and Canto do Amaro, Brazil. 
Niu, et al.[154] published the field application results for an amphoteric PAM copolymer 
in China.

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2.5