Feasibility Research Of Low Internacial Tension Oil-Displacing Surfactant System In Mid-Low Permeability Oil Layers

Nowadays, the water drive recovery efficiency factor in low permeability reservoirs is low, in order to solve this puzzle, this paper adopts betaine surfactant and low molecular polymer to form low interfacial tension flooding system, does some experiments with the medium -low permeable cores, which includes artificial core flooding experiments and natural core flooding experiments. The core in the artificial core flooding experiments includes artificial homogeny ones and artificial anisotropic ones. The results from the artificial cores active water flooding experiments show that the traditional water flooding effect is not good which can improve from 4.93% to 6.71%, but just 4.41% in the artificial anisotropic cores, the injection of the active water can lower the injecting pressure to some extent, the injection of the active water plug at different time influences the total recovery quite a lot, when the active water plug is injected at first ,the total recovery is higher and the total injected pore volume time is smaller, but for the anisotropic core, the injection time has almost no influence on the total recovery. When the injection condition is the same, the recovery of injecting the combination plug (BS13,0.1%+polymer,400ppm) is 3.71% higher than that of injecting purely BS13 active water (0.1%). For the artificial homogeny core, the recovery of injecting polymer(400ppm)first then BS13 active water is 2.44% higher than the combination plug(BS13,0.1%+polymer,400ppm),but for the anisotropic core, the improving percent of the recovery is almost the same. The size of the combination plug influences the recovery to some extent, the improving percent of the recovery when injecting 0.3 time pore volume polymer is higher than that when injecting 0.2 time pore volume polymer. the results from the natural core indicate that the flooding effect of the composite plug(BS13 active water, 0.1%+polymer,400mg/L) is better than that of the pure active water, and is3.17%～6.66% higher than that of pure BS13 active water. The flooding effect of the composite plug (SY active water,0.1%+polymer,400mg/L+ Na2CO3) is not good as that of the composite plug(BS13 active water,0.1%+plymer,400mg/L, and the injected pressure of the former is higher, which is not good for the field application.