Study on the mechanism of improved oil recovery by nitrogen foam flooding in bottom water reservoirs

There are abundant bottom water reservoirs in China. Unlike conventional oil reservoirs, have various problems, such as early breakthrough, short water-free recovery period, and rapid cut increase. For example, during flooding, the injected easily breaks into does not effectively displace upper crude oil. The rate is generally low. Based on this phenomenon, an experimental study of nitrogen foam flooding conducted paper. seepage characteristics layers studied through one-dimensional core tube experiments. Through two-dimensional plate displacement experiments, we revealed fluid migration distribution plane vertical directions reservoirs; additionally, summarized mechanisms involved improving characteristics. research results show that resistance layer much greater than layer, increasing strength layer. During development stage increases rapidly, coning obvious, residual mainly distributed between wells part near wellbore. enters to form effective plug so subsequent diverted layer; displaced laterally production well for production. When it defoams floats a secondary gas cap; effect causes at top improves efficiency by weeping volume fluid”