In this article, the morphology, particle size, and plugging properties of crosslinked polyacrylamide (CPAM) microspheres were investigated through optical microscopy, scanning electron microscopy (SEM), nuclear-pore membrane filtration experiments, a micro-visual model, sandpack experiments, parallel twin-tube plugging, and oil displacement experiments. The results revealed that the primary particle sizes of the CPAM microspheres ranged from several hundreds of nanometers to 5 lm; however, after the microspheres were fully swelled in water, their sizes increased by approximately five times of their original sizes. As a CPAM microsphere dispersion system had good dispersibility and deformation capabilities, a 1.2 lm nuclear-pore membrane as well as the deep part of a sandpack tube could be effectively plugged. Consequently, the flow diversion effect was achieved in the vertical and planar directions. When the CPAM microspheres migrated in porous media, they could displace residual oil on the pole wall and water flow channel to realize the synchronization of profile control and coordination and improve recovery efficiency. V C 2016 Wiley Periodicals, Inc. J. Appl.Polym. Sci. 2016, 133, 43666.

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Thermal flooding by steam injection was a traditional method for exploiting heavy oil. The produced liquid was a highly stable water-in-oil or oil-in-water emulsion in several oilfields. In this work, we focused on studying the effect of high temperature on the stability of an emulsion system involving two typical crude oils (heavy crude oil and light crude oil) and brine. It was impossible to directly measure the interfacial viscoelastic modulus because of the high viscosity of the heavy oil. In order to solve this problem and analyze the contribution of those fractions to the formation of stable emulsions, the heavy crude oil was divided into three cuts: remaining fraction, resin, and asphaltene. The model oils were prepared from the mixture of several heavy crude oil fractions with kerosene:xylene (1:1 v/v) to investigate the high-temperature behaviors of their emulsions. The stability was evaluated through a high-temperature–high-pressure (HTHP) visual pressure–volume–temperature cell, and a temperature up to 200 °C was achieved. The automatic pendant drop technique was used to analyze the interfacial rheology of model oils/brine system under HTHP conditions. With increasing formation temperature, the kinetically stable heavy oil emulsion had a much higher viscosity. The stabilities of heavy crude oil and light crude oil emulsions had opposite trends as the formation temperature increased. The stabilities of different model oils indicated that the mass fraction of asphaltene was responsible for the stability of emulsions at high temperature. With increasing temperature, the interfacial viscoelastic properties stabilized by 4.0 wt % asphaltenes had an increasing trend, but the stability of remaining fraction, resin, and 0.4 wt % asphaltene had a decreasing trend. The mechanism of formation of a stable and more rigid interfacial film was revealed by the effect of high temperature on asphaltene aggregation and water molecules.