| Dispersed profile control and flooding technology is the main measure to improve oil recovery in offshore high water cut oilfields,which has a wide range of applications.However,there are great differences in its injectivity and long-term effectiveness in the application of medium and low permeability reservoirs in the South China Sea.In order to further improve the implementation effect of decentralized profile control and flooding technology in WZ oilfield,this paper proposes to carry out the research on the mechanism of decentralized profile control and flooding technology to improve the recovery rate of WZ oilfield,aiming to further clarify the essential differences of different types of decentralized profile control and flooding systems,as well as the dominant factors affecting their injectivity,plugging and oil displacement performance in porous media,laying a foundation for better guiding scheme design and production practice.In this paper,the geological reservoir characteristics of WZ oilfield group in the South China Sea are taken as the research object,the physical chemistry,polymer materials and reservoir engineering are taken as the theoretical guidance,and the chemical analysis,instrument detection and physical simulation are taken as the technical means.The mechanism of dispersed profile control and flooding technology(HTRN,PRM)to improve the recovery rate of WZ oilfield is studied.The main achievements and understandings are as follows :(1)HTRN has good water absorption and expansion performance,the initial particle size is 0.25μm,the particle size of hydration 9d is expanded by 13 times,and the average particle size is 3μm.The initial particle size of PRM was 0.9μm,and the particle size did not change much during the whole hydration period.(2)HTRN Young ’s modulus 3.8Gpa > PRM Young ’s modulus1.9Gpa,indicating that HTRN has greater hardness and is easier to play the role of a single spherical particle in the deep reservoir to block the macropore throat.On the contrary,PRM is different from the bridging plugging of HTRN particles.Its Young ’s modulus is small and easy to deform.It mainly relies on formation adsorption to produce plugging,which has a great correlation with the non-expansion of the particle size of the system.(3)The injectivity and plugging performance of the dispersed profile control and flooding system are affected by many factors such as mass concentration,hydration time,injection slug,injection rate and core permeability.The mass concentration and injection slug size are the most important factors,and they are also important parameters for field scheme design.(4)There are differences in the range of permeability differential regulation between the two decentralized profile control systems.Under the conditions of permeability differential multiples of 5,10 and 20,HTRN fluid flow steering ability and its pressurized profile control effect are better than PRM.(5)The watercut of the reservoir has an effect on the effect of the dispersed profile control system,EOR(watercut 80 %)> EOR(watercut 90 %);when the core watercut is 80 %,EOR(high concentration)> EOR(low concentration).(6)There are differences in the priority influencing factors of the two decentralized profile control systems.HTRN is greatly affected by the difference of reservoir watercut.When the watercut is relatively low,the oil displacement effect is better.PRM is greatly affected by the mass concentration difference of the flooding system.When the injection mass concentration is relatively large,the effect of supercharged flooding is better. |
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