Partially hydrolysed polyacrylamide

Minerals. The polymer used in this study is partially hydrolysed polyacrylamide (HPAM), supplied by Allied Colloids Ltd, Low Moor, Bradford, West Yorkshire, England, UK. Approximately 10mol% of the monomer units are hydrolysed and are present as sodium acrylate with a polyacrylamide-coacrylate copolymer having a molecular mass of approximately 6 x lO D. The study minerals quartz, kaolinite and feldspar were collected from the Lee Moor China Clay Pit in Devon, UK. Mica was obtained in sheet form from Agar Scientific. 

Assuming a typical oil reservoir containing medium heavy-crude oil and employing a reservoir flow rate of 0.26 m/day. The solution viscosity could be increased to 30 mPa S by adding about 1000 pgml- (0.1%) partially hydrolysed polyacrylamide polymer (at pH 8.5). The interfacial tension could be reduced to 0.1 mN m by adding 1% sodium carbonate, which reacts with the crude oil to produce natural surfactant. The interfacial tension could be further reduced to 0.03 mN m by adding 0,1% ethoxylated alcohol sulfate co-surfactant. 

Partially hydrolysed polyacrylamides, however, exhibit a high viscosity level due to coil expansion, but succumb to aging and are not stable to multivalent cations (precipitation). 

Partially hydrolysed polyacrylamide (HPAM) and its corresponding sodium salt. 

Figure 2.9. The primary chain structure of polyacrylamide (PAM) and partially hydrolysed polyacrylamide (HPAM).

The quoted molecular weights of partially hydrolysed polyacrylamide... 

Figure 4.3. Dependence of precipitation time on temperature for partially hydrolysed polyacrylamide (31% hydrolysis) in seawater (from Davison and Mentzer, 1980).

The main objective in this section is to look at the degradation mechanisms for xanthan and partially hydrolysed polyacrylamide in more detail. The mechanisms of both short-term oxidative attack and longer term hydrolysis and/or precipitation are discussed. A study of these mechanisms gives some helpful pointers towards molecular modifications which may improve the stability of new polymers for oil recovery applications. 

Argabright, P. A., Rhudy, J. S. and Phillips, B. L. (1982) Partially hydrolysed polyacrylamides with superior flooding and injection properties. SPE 11208, Proceedings of the SPE 57th Annual Fall Conference, New Orleans, LA, 26-29 September 1982. 

Maerker, J. M. (1975) Shear degradation of partially hydrolysed polyacrylamide solutions. Soc. Pet. Eng. J. August, 311-321 (Trans. SPE-AIME 259). 

Smith, F. W. (1970) The behaviour of partially hydrolysed polyacrylamide solutions in porous media. J. Pet. Tech. 22, 148-156. 

Smith, F.W., The behaviour of partially hydrolysed polyacrylamide solutions in porous media. 

Maerker, J.M., Shear degradation of partially hydrolysed polyacrylamide solutions. 

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