Study On Polymerization/Table Binary Composite System Suitable For Ordinary Heavy Oil Reservoirs

The polymer flooding could increase oil recovery at 8%-15%, while in Bohai, where the crude oil left in the formation is remained at 45%-55%, oil recovery only rose to 4%-8%. Hence, more effective chemical flooding technologies needed to be searched to go up the heavy oil recovery. Under the condition of high oil viscosity and high formation permeability in Bohai SZ36-1 offshore, the solution properties of DHAP with high thickening performance were specificly studied, and the surfactants matched well with DHAP were selected to obtain the polymer/surfactant binary systems that might enhance the heavy oil recovery effectively and efficiently.To begin with, based on the aforementioned condition of Bohai offshore, the solution properties of DHAP were charactered, which led that DHAP not merely performed well in tackifying and injectivity, but established high RF and RRF in porous media, thus accordingly meeting the requirement of mobility control.Anionic, Nonionic and Zwitterionic surfactants were chosen to mix with DHAP which performed well in mobility control, and Zwitterionic surfactant (HSB-16) could reduce the interfacial tension, additionnally, slightly decreasing the apparent viscosity of the solution.The stratifiction didn't appear in the binary systems of the DHAP-HSB-16 and the viscosity of the solution reduced while the interfacial tension maintained stability during the aging test. The DH-2 and the DH-4 were opted and their solution properties were studied.The results showed that the DH-2 and the DH-4 exhibited flow stability in porous media and could be used as a displacing agent.The preferred binary systems were used for flooding experiment, which revealed that the polymer/surfactant binary systems could enhance the heavy oil recovery effectively comparing with polymer flooding and surfactant flooding. The oil recovery of the DH-5 was lower than the the DH-2 and the DH-4. Though the interfacial tension of the DH-5 could reach to the ultra-low level and the interfacial tension of the DH-2 and the DH-4 were about 0.1mN/m, the viscosity of the DH-5 was significantly lower than the DH-2 and the DH-4. So it could be concluded that enhancing oil recovery of the high permeability heavy oil reservoirs needed to improve the swept volume, which could open up a new way of thinking in screening the polymer/ surfactant binary systems which were used in heavy oil reservoirs.