A study of rheology and interfacial activity of amphiphilic block copolymers for enhanced oil recovery

In this study two types of amphiphilic block copolymers -diblocks and multiblocks--are synthesized, modified, and characterized with the objective of proposing new amphiphilic block copolymers and studying the rheological behavior and surface and interfacial activities for use in enhanced oil recovery operations. Two systems of polymers mainly heavily studied in this investigation namely poly(acrylamide-block-styrene) and poly(acrylamide-block-dodecene). Other systems which are copolymers of methylmethacrylates are studied along with homopolymers and random copolymers for comparison purposes. Methylmethacrylate copolymers are then hydrolyzed and characterized, samples HD2, HD6, and HD8.; The rheological behavior and surface/interfacial activities of both systems are thoroughly studied with respect to polymer concentration, salinity, shear rate, temperature, storage time, polymer molecular weight and addition of surfactants. The viscosity of di-polyelectrolytes (HD2, HD6, and HD8) exhibit moderate thickening ability and surface and interfacial activity. However, HD2 exhibits a viscosity of 1000 cps at 0.8 shear rate. Also sample HD8 (sodium poly(methacrylaate-block-vinylemadazol) exhibits the highest surface and interfacial activity demonstrated by low values of surface and interfacial tensions (8.1 and 1.87 mN/m respectively) at 1.5 wt% as polymer concentration or 15,000 ppm. Moreover, this copolymer exhibits salt tolerancy beyond 10 wt% NaCl. For other block copolymers it was found that samples E3 or poly(AM-b-C12) and P12 or poly(AM-b-ST) exhibit higher surface and interfacial activities compared to other multi-block copolymers studied. E3 showed low water-polymer interfacial tension of 0.5 mN/m at 10 wt% NaCl. Multi-block copolymer P12 was found to exhibit the highest thickening ability (10,110 cps.) at high salinity (10 wt%) among other copolymers investigated as well as high surface and interfacial activity (43.1 and 1.01 mN/m respectively) at 10 wt% NaCl and polymer concentration of 1.5 wt%. Therefore P12 considered to be a good candidate for enhanced oil recovery operations.; Generally, all systems of block copolymers exhibit typical shear thinning behavior at low shear rates and constant viscosity at high shear rates. Moreover, increasing polymer concentration give rise to an increase in the polymer solution viscosity and an increase in surface and interfacial activities. Also all polymers exhibit smaller decrease in solution viscosity at high temperatures and storage time.; It is concluded from this study that by controlling the distribution of the hydrophobe sequences along the polymer backbone, and its nature/type/level used, and by varying the experimental design conditions, the polymerization route, the polymer architecture, and the micellar concentration, it was found that longer hydrophobic sequences (blocks) give rise to higher degree of intermolecular hydrophobic interactions/associations and therefore to a greater thickening efficiencies to amphiphilic block copolymer solutions. (Abstract shortened by UMI.)...