Polyacrylamide and its derivatives for oil recovery

Figure 4.
Structure of monomer in KYPAM. [130]
 
In Figure 4, R
1
and R
2
represent either a H or C
1
-C
12
alkyl, R
3
and R
4 
are C
1
-C
12
alkyl, C
1
-C
12
alkylaryl, C
1
-C
12
alkyl ether, or a C
1
-C
12
alkyl-ester group. The structure 
variable “A” is carboxyl (COOH), alcohol (OH), or sulfoxyl (SO
3
H). The iterative 
polymer was tested in Daqing oilfield where the results showed the viscosity of the 
KYPAM comb-shaped, salt-resistant industrial polymer maintained solution viscosity 
above 40 mPa∙s, ~41.2% higher than that of conventional polyacrylamides.
Recently, Xu, et al.[134] reported a nonionic but amphiphilic, comb-type 
polyacrylamide structure. They first synthesized a nonioinic, amphiphilic macro-mer,
 t
-
octylphenoxypolyoxyethylene(OP) acrylic ester (OPAE) by esterification of acrylic acid 
(AA) with OP. The macro-mer was then copolymerized with acrylamide (AM) under a 
free radical initiation system and alkaline environment. Upon precipitation in acetone, a 
comb-type polymer of mixed structure, P(AM-OPAE) and P(AM-AANa-OPAE) with 17 
mol.-% degree of hydrolysis was obtained. Solutions of the P(AM-AANa-OPAE) have a 
significantly higher apparent viscosity than HPAM solutions under identical 
concentration and shear rate conditions. Since both hydrophilic and hydrophobic side 
chains were introduced into the backbone of the polymers, the apparent inter-chain 
repulsion reduces polymer coil collapse in solution, the curling behavior, so that the salt-

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resistance and shearing-resistance were also improved compared to HPAM solutions. In 
field applications, KYPAM was tested at the Lamadian oilfield, Daqing, China, which 
was of area 3.45 km
2
. From May, 2001 to December, 2002, KYPAM improved average 
oil production rate by a factor of 4.6, which correspondingly increased oil recovery by 
2%, compared to ultra-high molecular weight PAM solutions. Since 2003, KYPAM has 
been widely used in the Daqing oilfield. Similar practical application was implemented in 
the Shengli oil field, from 2001 to 2003(see Table 1. KYPAM solutions were also applied 
in the Huabei Oilfield, which increased the oil production rate from 37 to 71 tons per day, 
totally 12,000t and water-cut was decreased from 92.1% to 89.2%.[135-137]