Hydrophobic associating polymers

J. Bock and co-workers, "Hydrophobically Associating Polymers," ia G. A. Stahl and D. N. Schul2, eds., Water-Soluble Polymers for Petroleum Recorey, Plenum Press, New York, 1988, pp. 147—160. 

Copolymerization of the CD-complexed macromonomer 8a with hydrophilic comonomers 2-acrylamido-2-methylpropansulfonate (AMPS) and A,A-dimethyl-acrylamide (DMAA) leads to formation of hydrophobically associative polymers (Fig. 14) [48],... 

The polymer is hydrophobically associating water soluble, meaning it contains one or more water-soluble monomers (acrylamides) and a small fraction (0.5 to 4%) of water-insoluble (hydrophobic) monomers. A typical hydrophobically associating polymer (HAP) structure is... 

This shear reversibihty is very beneficial in enhanced oil recovery field applications. It improves the well injectivity because of the shear thinning effect at the perforation and near the wellbore. Far away from the wellbore, flow velocity is reduced and viscosity is restored. For the hydrophobically associating polymers, both shear thickening and shear thinning were observed by Bock et al. (1988). It has also been reported that the viscosity after shearing was stopped was higher than that before shearing (McCormick et al., 1988). 

Core flood results show that the oil recovery factor using hydrophobically associating polymers was a few percent higher than that using the HPAM type of polymers (Wang et al., 1999c On-Yang et al., 2004 Luo et al., 2006). The... 

Chen, H., Zhang, S.H., Chu, Y.B., Yang, H.X., Liu, F.L., 2004. Development and application of hydrophobically associating polymer gel in high-temperature and high-salinity reservoirs for profile modification. Oilfield Chemistry 21 (4), 343-346. 

Polymerization of Hydrophobically Associating Polymers. The following procedure for the preparation of 0.75 mol % N-4-butylphenylacrylamide-acrylamide polymer is typical of all the polymers discussed in this report. 

Hydrophobically associating polymers consist primarily of water-soluble monomer units with a small number of water-insoluble monomer units. Synthesis of high-molecular-weight random copolymers of acrylamide and alkylacrylamides required a novel aqueous surfactant micellar solution polymerization (2-4) because of the mutual immiscibility of the water-soluble and hydrophobic monomers. The use of surfactant micelles enabled solubilization of the hydrophobic monomer (alkylacrylamide [R]) into the aqueous phase containing the water-soluble monomer (acrylamide [AM]). The resulting RAM polymer after isolation provided homogeneous aqueous solutions. 

X HE RHEOLOGICAL PROPERTIES OF WATER-BASED FLUIDS can be controlled with hydrophobically associating polymers. Hydrophobically associating polymers are synthetically derived, water-soluble polymers that contain a small number of oil-soluble or hydrophobic groups. When these polymers are dissolved in aqueous solution, the hydrophobic groups aggregate to minimize their exposure to water, in a fashion analogous to that of surfactants... 

A further complication to understanding the rheology of hydrophobically associating polymers is their unique response to shear rate and solvent quality (e.g., salt content). As shown in Figures 5 and 6, the viscosity can be independent (Newtonian), decrease (pseudoplastic), or even increase (dilatant)... 

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