Abstract
In order to obtain polymer microsphere for profile control and water shutoff with good suspension, high temperature resistance and high salinity tolerance, micrometer DCA (divinylbenzene-co-acrylamide) microsphere which had a three-layer structure was synthesized by the monomer of acrylamide, initiator of azobisisobutyronitrile, crosslinking agent of divinylbenzene and emulsifier of ethoxylated lauryl alcohol sulfate. Basic performance of DCA microsphere was evaluated, including temperature resistance, plugging capacity, effect of profile control and water shutoff and method optimization. The results showed that the particle size of DCA microsphere ranged from 2 μm to 339 μm and the shell had a Nano porous structure. The temperature resistance of DCA microsphere was up to 300°C. The residual resistance coefficient of each segment along artificial homogeneous cylindrical core was still more than 2 with a strong deep plugging efficiency. After water flooding of oil in two-dimensional heterogeneous cores was carried out, the slug of DCA microspheres was injected. The amplitude of enhanced oil recovery was up to 10.18% in stage of the subsequent water flooding. On the basis of the subsequent water flooding, the recovery of carbon dioxide flooding was 19.64%. Feasibility methods which were the plugging of DCA microspheres and carbon dioxide flooding on deep profile control technology in high permeability of high temperature and high salinity reservoirs have been roposed.
Highlights
Profile control and water shutoff are still considered technical problems for high-temperature and high-salinity reservoirs
Deep profile control and water shutoff have been implemented in reservoirs using the new technology of the polymer microspheres
Deep profile control of polymer microspheres which was used in oilfield mainly was synthesized by the methods of inverse emulsion polymerization [1], inverse suspension polymerization [2] and the dispersion polymerization [3]
Summary
Profile control and water shutoff are still considered technical problems for high-temperature and high-salinity reservoirs. Given that the conventional agents of profile control and water shutoff have many disadvantages, their performance in terms of high temperature and salinity tolerance is poor. Their cross-linking reaction time is difficult to control, and the validity period of the operation measures is short. The advantage of polymer microspheres includes hightemperature and high-salinity tolerance, good suspension, migrating into the deep reservoir to real-time plugging, the long valid period of the operation measures. The first category of profile control agent of polymer microspheres was successfully applied in the part of middle or high permeability reservoir in the domestic and achieved good effect of profile control and water shutoff. The temperature resistance and good suspension of these three categories of microspheres are poor
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