中高渗胶结油藏聚合物驱后非均相复合驱技术

双河油田始新统核桃园组Ⅳ1-3层系具有高温和中高渗的特点,聚合物驱后进入特高含水阶段,需要进一步提高采收率技术。非均相复合驱油体系兼具扩大波及体积和提高洗油效率的作用,可以有效调整剖面,控水增油。基于黏弹性和界面活性,研究了非均相复合驱油体系的长期热稳定性,利用单根岩心研究其注入性和运移方式,利用双管并联岩心驱替实验评价其驱油效果。研究结果表明,非均相复合驱油体系为黏弹性复合体系,弹性占主导地位。其黏度较聚合物驱油体系高58%~197%,弹性模量较聚合物驱油体系高67%~227%。界面张力处于10^-3 mN/m数量级,具有良好的洗油作用。非均相复合驱油体系具有良好的长期热稳定性,老化180 d后,黏度和弹性模量保留率超过100%,界面张力仍处于10^-3 mN/m数量级。非均相复合驱油体系注入性好,能够在高强度聚合物驱后进一步提高采收率16.93%。非均相复合驱油体系的运移方式为运移、堆积、封堵、变形通过,通过启动低渗区被毛细管力束缚的剩余油,使油相饱和度显著降低。将非均相复合驱的应用范围从低温、高孔高渗疏松油藏拓展到了高温、中高渗胶结油藏。

Heterogeneous Compound Flooding Technology for Medium-High Permeability Consolidated Reservoir After Polymer Flooding

The Ⅳ1-3 layers in Eocene Hetaoyuan formation in Shuanghe oilfield are characterized by high temperature and medium-high permeability. At present, the layers have entered a development stage with ultra-high water cut after polymer flooding, and it is necessary to further improve the recovery. Heterogeneous compound flooding system can effectively expand swept volume, improve oil displacement efficiency, adjust production and injection profiles, control water production and increase oil production. We studied the long-term thermal stability of the system based on viscoelasticity and interfacial activity. Using a single core, we investigated the injectability and moving style of the heterogeneous compound system in reservoir. Through a parallel core displacement experiment, we evaluated the oil displacement effect of the system. The research results show that the heterogeneous compound flooding system is viscoelastic and its elasticity is dominant. The viscosity of the heterogeneous compound flooding system is 58%~197% higher than a conventional polymer flooding system, and the elastic modulus of the former is 67%~227% higher than the latter. The interfacial tension of the heterogeneous compound flooding system is at the magnitude of 10 ^-3 mN/m, so it is good at displacing oil. In addition, the heterogeneous compound flooding system can keep thermal stability for a long time. For example, after 180 days of aging, the retention rates of the viscosity and the elastic modulus exceed 100%, and the interfacial tension is still at the magnitude of 10^-3 mN/m. The system has good injectivity, which can further increase the recovery by 16.93% after high-strength polymer flooding. The system moves in reservoirs in ways of migrating, accumulating, plugging, and deforming to move. By displacing the residual oil bound by the capillary force in less permeable zones, the heterogeneous compound flooding system can significantly reduce oil saturation. This research expands the application of the heterogeneous compound flooding from unconsolidated oil reservoirs at low temperature, and with high porosity and high permeability to consolidated reservoirs at high temperature, and with medium to high permeability.