Polyacrylamide and its derivatives for oil recovery

Figure 3. 
Structure of monomer B in KYPAM. [130]
 

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27 
Where R
1
,R
2
,R
3
could be H or C
1
~C
12
alkyl, R
4
could be C
1
~C
12
alkyl, C
1
~C
12
alkyl aryl, 
C
1
-C
12
alkyl ether, or C
1
-C
12
alkyl ester group. A is to contain an 
ionic functional group insensitive to Ca
2+
and Mg
2+
. Monomer B is prepared by 
dissolving 10-hydroxydecanoate in ethyl alcohol and addition of propylene chloride. The 
addition of caustic soda solutions drop by drop with heating and refluxing produces the 
monomer B upon removal of ethyl alcohol and water. A salinity-resistant thickener is 
then synthesized by adding monomer B, and acrylamide or its derivative, to monomer of 
Figure 3 with (NH
4
)
2
S
2
O
8
and NaHSO
3
or AIBN as initiator. The monomer blend is, 
polymerized over ten hours producing a viscoelastic hydrogel.[130] Since the year 2000, 
KYPAM has been applied to EOR in reservoirs in China, such as Daqing, Shengli, and 
Kelamayi. Good performance has been reported there in comparison to conventional 
PAM. Under the same conditions, KYPAM increased flood solution viscosity by 50% in 
salt water providing a 100% increase in flooding efficiency. In addition, water cut in 
oilfield was decreased 15.5% more than using PAM and oil production was enhanced 4.6 
times greater than water driving, resulting in a 2% increase in overall recovery ratio.[132] 
Based on research into comb-shaped KYPAM polymers, Petrochina Company 
Limited has developed and now commercially manufactured, braided comb-shaped 
polymer products. Yuan, et al.[133] synthesized a series of braided comb-shaped, salt-
resistant thickening agents using the similar preparation method as KYPAM (summarized 
above). The copolymerization is a free radical copolymerization initiated by azo-
bis
-
isobutyronitrile that results in a polymer suited for assisting liquid flood tertiary oil 
extraction. The early KYPAM iterative comb-shaped polymer thickening agent is 
copolymerized with one, or multiple, water soluble unsaturated compound(s), such as 

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28 
acrylamide, vinyl pyrrolidone, 2-acrylamide-2 methyl propane sulfonic acid, acrylic acid 
and mixtures thereof, and a series monomer analogous to Figure 3 (depicted in Figure 4). 
C
C
R
1
R
2
R
3
R
4
A
A