Controllable preparation,rheology, and plugging property of micron‐grade polyacrylamide microspheres as a novel profile control and flooding agent

A series of micron‐grade polyacrylamide microspheres were prepared by inverse suspension polymerization of acrylamide (AM) and N,N′‐methylene bisacrylamide (MBA) in oil phase, with Span80 and Tween80 as dispersion stabilizers, and ammonium persulfate (APS) as an initiator. The conversion rate and coagulum rate were introduced to optimize the inverse suspension polymerization conditions of micron‐grade polyacrylamide microspheres. The swelling property of polyacrylamide microspheres in aqueous solution and the rheology of polyacrylamide microspheres suspension were characterized. The matching factor was introduced to characterize the matching relationship between the particle size of polyacrylamide microspheres and pore‐throat size of reservoirs. The optimized synthesis results show that the conversion rate is high, and the coagulum rate is low when the mass ratio of Span80 to Tween80 is 3 : 1. The particle size of the polyacrylamide microspheres is controlled by varying the concentration of dispersion stabilizer. The polyacrylamide microspheres show an obvious swelling property, which depends on the concentration of NaCl and temperature. The polyacrylamide microspheres suspension shows different rheological properties at different temperature and shear rate. When the temperature is low, it behaves as pseudoplastic fluid, dilatant fluid and quasi‐newtonian fluid in turn with the increase of shear rate. When the temperature is high, it behaves as dilatant fluid and quasi‐newtonian fluid in turn with the increase of shear rate. The micron‐grade polyacrylamide microspheres prefer to plug sand pack with optimal matching factor. When the matching factor is 1.35–1.55, the polyacrylamide microspheres can be transported into the deep area of sand pack, and the ultimate plugging rate is more than 85%, which indicates that the matching factor is an effective parameter to evaluate the matching relationship between polyacrylamide microspheres and reservoirs. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 130: 1124‐1130, 2013