Evaluation of hydrophobically associated polyacrylamide‐containing aqueous fluids and their potential use in petroleum recovery

Abstract

Acrylamide and tridecyl acrylate copolymers were synthesized by micellar copolymerization to obtain water-soluble, hydrophobically modified polymers. Rheological properties of the obtained polymer solutions were evaluated and compared to those of solutions of a commercial polyacrylamide currently used in the petroleum industry. The behavior of the copolymer solutions was studied as a function of the variation of hydrophobic monomer content incorporated in the copolymer as well as the salt content of the aqueous medium, for diluted and semi-diluted regimens. Comparative studies of such effects on the intrinsic viscosity and the critical concentration of those polymers were conducted. The increase in hydrophobic monomer content produced a sudden increase in the bulk and absolute viscosity of the polymeric solutions, a trend that was more intense from a certain concentration typical for each polymer. Salt addition led to lower bulk viscosity caused by a stronger interaction among hydrophobic groups, resulting from minimized exposure of such groups and water. The same effect was observed for the critical concentration. A comparison of the synthesized polymers with industrial polyacrylamide showed that the synthesized polymers were characterized by advantageously high shear strength and high salt resistance. However, in the absence of salts, higher copolymer amounts were needed to prepare solutions whose viscosity was the same as that of commercial polyacrylamide.

Experimental investigation of the effect of different process variables on the viscosity of sulfonated polyacrylamide copolymers

“…These findings were consistent with those of other studies (AitKadi et al 1987;Chagas et al 2004;Rashidi et al 2010). The addition of NaCl to the polymer solution shielded the charges on the polymer chain.…”

“…A viscosity reduction with the shear rate is noticed for pseudo-plastic or shear thinning fluids. The orientation of macromolecules along the stream line of the flow is considered to be the reason for the pseudo-plastic behavior (Ait-Kadi et al 1987;Ballard et al 1988;Carreau 1972;Chagas et al 2004;Ghannam 1999). For all polymers, a higher polymer concentration gives a solution with a higher viscosity.…”

“…The addition of NaCl to the polymer solution shielded the charges on the polymer chain. The molecules then coiled up and resulted in a lower polymer solution viscosity (Ait-Kadi et al 1987;Chagas et al 2004;Rashidi et al 2010). The rate of the decrease in the viscosity began to level off after a particular salinity as all charges on the polymer chain had been screened by the NaCl ions.…”

“…Several studies have been conducted, comprehensively and at length, on the viscosity of polymers, such as polyacrylamide (PAM), hydrolyzed polyacrylamide (HPAM), biopolymers, etc. (Bendell et al 1989;Carreau 1972;Chagas et al 2004;Dong et al 2008). Synthetic polymers, such as HPAM, are used in EOR processes as seen in the Daqing and Bohai oil fields with a low concentration of salinity and hardness (Dong et al 2008;Han et al 2006).…”

Comparison of neuro-fuzzy network and response surface methodology pertaining to the viscosity of polymer solutions

“…The macromolecules orientation along the flow stream line is a good justification for the observed shear thinning behavior of the solution as has been highlighted by different researchers (Ait-Kadi et al 1987;Ballard et al 1988;Carreau 1972;Chagas et al 2004;Ghannam 1999).…”