Polyacrylamide and its derivatives for oil recovery

Figure 6. 
Structure model of the gelation of polyacrylamide/nanoclay gelant solution. 
[
161]
 

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36 
Figure 7. 
Schematic illustration of force acting on a pair clay layers during interaction. 
[162]
 
Few open articles have been reported for clay modified polyacrylamides used as 
drilling fluid in polymer flooding, however a plenty of crosslinked hybrid gels have been 
used as gel treatment in profile control. Y. Mansoori et al.[165] did grafting of 
polyacrylamide onto organophilic montmorillonite and obtain a kind of material 
(PCN:polyacrylamide-clay-nanocomposite) with obvious enhanced heat resistance. The 
glass transition temperature increased dramatically from 117.0 ͦ C (pure PAM) to 178.0 ͦ C 
for PCN modified with 7wt.-% clay. This hybrid idea may also be applied in synthesizing 
polymers for EOR to increase the heat tolerance of displacing fluid. By contrast with 
clay, inorganic particles were tried as modifier to design polymers as drilling fluid. 
David Portehault et al. synthesized copolymer polyacrylamide-co-poly(sodium 
acrylate)-g-poly N-isopropylacrylamide hybrideing with hydrophilic silica nanoparticles 
and investigated the interactions between the polymer chains and inorganic 
nanoparticles.[166, 167] They found the poly N-isopropylacrylamide (PNIPA) per-se 
strongly interacts with silica surface, adsorbing irreversibly on the particles under low 
temperature, and this affinity decreased sharply to phase separate upon heating. After 

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37 
grafted to the poly(acrylamide-sodium acrylate), PNIPA worked as side chains still 
preserved their affinity for silica forming responsible bridges among polymer chains and 
inorganic nanoparticles and establishing hybrid networks when enough silica added into 
copolymer solution. Based their achievements, Dingwei Zhu et al.[102] prepared similar 
system for drilling fluids of EOR and investigated their properties both in pure water and 
brine. They pointed out that at lower polymer concentration (< CAC), less hybriding 
interaction occured due to aggregation; when polymer concentration reached to CMC, 
silica nanoparticles acted as physical crosslinkers among the entangled polymer chain, 
owing to attraction between carbonyl groups in HAPAM and silanol groups at the surface 
of nanoparticles; at higher polymer concentration (> CAC), minor enhancement in 
viscosity id observed. This hybriding polymer had better thermal stability than pure 
HAPAM. The viscosity retention ratio of the hybrid is 43%, compared to 17.47% of pure 
HAPAM at 85 ͦ C for 60 days. 
In the Athabasca area of Alberta, Canada, oil sand ores are low grade with high 
concentration of mineral solids, chemical aids are often needed in bitumen extraction. 
Hihong Li et al.[168] employed hybrid Al(OH)
3
-polyacrylamide (Al-PAM)[169, 170] 
combing with a partially hydrolyzed polyacrylamide (HPAM) to process a low-grade oil 
sand ore. It appeared that Al-PAM could enhance fine clay flocculation and be capable to 
improve both bitumen froth quality, tailings settling and bitumen recovery.[171] For the 
synthesis process, they firstly prepared Al(OH)
3
colloidal with uniform size through 
2AlCl
3
+3(HN
4
)
2
CO
3
+3H
2
O=2Al(OH)
3
+6(NH
4
)Cl+3CO
2 
under strong agitation, then 
polymerized acrylamide monomers in Al(OH)3 colloidal with (NH
4
)
2
S
2
O
8
-NaHSO
3
as an 
initiator. Hybrid polymer was acquired after washing filtration and vacuum dry.

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38 
Although the research in these areas appears promising, few open practical 
applications of HAPA have yet to be published due to synthetic limitations, e.g., in 
product-control engineering and high chemical/product cost.