Abstract
Nano polymer microspheres are a new oil profile control system, which can be adjusted according to the formation pore throat. After hydration and swelling, the microspheres would reach the designed size and have relatively strong intensity. When the size of the microspheres is bigger than that of the formation pore throat or bridged blockage is formed, reliable blockage can be formed. The microspheres are elastic, which can deform and move forward under certain pressure, so that fluid diversion can be realized step by step and the request of movable agent is satisfied. The microspheres can resist high temperature to 110°C and high salinity to 200000mg/L (Ca2++Mg2+=3000 mg/L). To test its effect, this polymer microspheres technology is used at a serious heterogeneous and high temperature reservoir. The temperature of the test block is 98°C, and the salinity of injection water is 16380mg/L. The average permeability is 932×10‒3μm2, and the permeability contrast is obvious (high permeability is 4μm2, low permeability is 0.8μm2). Therefore, two sizes of microspheres are designed. The combination system of polymer microspheres and surfactant are injected, and the system is divided into five slugs. Double tubes physical modeling experiments are done, and the results show that the block off capacity of this design is competent, increasing oil recovery dramatically. Thanks to the accordant microspheres design and the rational injection design, this polymer microspheres technology has become the effective method for profile control and water plugging to serious heterogeneous and high temperature reservoirs.
