Study Of Heavy Oil Thermal/chemical Flooding

Properties of one surfactant for thermal recovery are studied experimentally. When WT solution and crude oil were mixed in the mass ratio of 3/7 and 2/8 at 70℃, oil viscosity can be dramatically decreased by more than 85%. Besides, WT has good temperature resistance at 150℃and 200℃, its half time is longer than 30 days. Static adsorption result shows that the maximum adsorption of WT on quartz sand at 70℃and 90℃is 3.6185mg/g and 2.333mg/g respctively. High temperature can greatly raise the foam volume, however decreases the foam stability. The interfacial tension (IFT) between WT solution and crude oil from Gudao third block is about 10-1mN/m, ultra-low IFT can be further achieved when the concentration of NaOH more than 0.5% was added.Heavy oil thermal/chemical flooding tests indicate that the oil recovery of steam flooding is about 6.0%higher than that of hot water flooding with the same temperature; thermal/surfactant flooding is 6.5%-12% higher than that of thermal flooding, but, the concentration of surfactant should not be more than 0.3wt%, when hot water/surfactant flooding; the incremental oil recovery of thermal flooding by addition of 0.5wt%NaOH is 6.0%-12% than thermal flooding; hot water/alkali/surfactant flooding has the highest oil recovery, the oil recovery is 12%-15% higher than that of hot water/surfactant flooding, exhibiting good synergistic effect between NaOH and WT.The effects of temperature and interfacial tension on the relative permeability of Gudao heavy oil were studied,The result shows that temperature has great influence on the relative permeability curve. When the temperature goes up, the oil and water relative permeability and the irreducible water saturation increase, while the residual oil saturation decreases. The study of displacement systems with different interfacial tension shows that the oil relative permeability presents an increasing trend with the decrease of interfacial tension. Water relative permeability is higher than that of water flooding as a whole. The irreducible water saturation and residual oil saturation show a reducing tendency with the decrease of interfacial tension.