Polyacrylamide and its derivatives for oil recovery

Figure 15. 
The surfactant of inverse-emulsion polymerization of acrylamide in ScCO
2. 
[304] 
Ohde et al.[303] synthesized polyacrylamide nanoparticles by inverse emulsion 
polymerization in ScCO
2
. The chosen surfactant was a perfluoropolyether-phosphate and 
the initiator was potassium persulfate. Through the inverse emulsion method, the 
nanoparticles were obtained with a size distribution between 50 and 200 nm.
Table 3 
The change of injection characteristic parameters before and after the polymer 
microsphere treatment.[306] 
Well
Before 
After 
Wellhead 
Pressure 
(MPa) 
Pressure 
index 
(MPa) 
Fill 
degree(%) 
Wellhea
d 
Pressure 
(MPa) 
Pressure 
index 
(MPa) 
Filling 
degree 
(%) 
A09 
7.0 
0.67 
10 
8.3 
5.15 
1.5 
B14 
4.9 
1.37 
35 
8.0 
5.05 
1.4 
C05 
1.0 
0.12 
12 
6.4 
4.80 
2.8 
C21 
1.1 
0.21 
21 
6.2 
4.63 
2.7 
Liu et al.[306] presented an oilfield application of polymer microspheres flooding 
in reservoir Q in Bohai Bay, China, which was a heterogeneous heavy oil reservoir 

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56 
suffering from fast water breakthrough with poor recovery. The pilot tests were done in 
four wells. Three types of polymer microsphere were used with the concentration of 
5000, 3000, and 5000mg/L, and injection pore volume of 0.01PV, 0.005PV and 0.015PV.
Good pore occlusion was observed, as shown in Table 3. Injection pressure, pressure 
index and filling degrees were greatly raised. Filling degree refers to measure the sealing 
pore volume and the unsealing pore volume. Additionally, the oil production decline rate 
was reduced from 7.0% to 4.9%, and water cut was reduced by 2.8% on average. 
Crosslinking polymer systems based on multiple cross-linkers were also adopted 
due to desire of multiple properties.[254, 283, 307]