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

Abstract

A series of micron-grade polyacrylamide microspheres were prepared by inverse suspension polymerization of acrylamide (AM) and N,N 0 -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.

Influence of thermal treatment and aging time on the stability and swelling properties of nano/micron‐sized polymeric spheres for improved oil recovery application

“…In this sense, it is necessary to guarantee that polymeric spheres have stability in the reservoir under harsh conditions. Literature has reported that the loss of the stability of the polymeric spheres is influenced by aspects such as the stabilizer content and the ratio between the components of the polymeric system . For this reason, the purpose of this section is to investigate the effect of the removal of the oil phase and stabilizers of the polymeric spheres on the system stability, the results are exhibited in Figure .…”

“…In particular, Yao et al . reported the synthesis of polymeric spheres by inverse suspension polymerization of acrylamide (AM) and N,N'‐methylene bisacrylamide (MBA) in the oil phase, with Span80 and Tween80 as dispersion stabilizers, and ammonium persulfate (APS) as an initiator …”

Preparation and Characterization of Hydrophobic-Associated Microspheres for Deep Profile Control in Offshore Oilfields

“…The slowly swelling properties prevent artificially high injection pressure from damaging to the formation. Recent researches have been carried out on the profile control mechanism of microspheres [8][9][10]. Slow swelling rate of microspheres avoids blocking in the zone close to the wells and increases core injectivity [3,11].…”

Preparation and properties of novel pH-sensitive core−shell microspheres for enhanced oil recovery

“…Polyacrylamide or acrylamide copolymer crosslinked microspheres used for reducing water cut to increase oil recovery have received extensive interest. The aspects of concern include the preparation, plugging performance, profile control performance, stability, mechanism of transport in porous media and so on.…”