RESEARCH ON AIR-FOAM/POLYMER-BASED PROFILE CONTROL AND FLOODING TECHNOLOGY IN HETEROGENEOUS RESERVOIRS

Air-foam injection flooding technology is one of the effective methods of tertiary oil recovery technology. But in the high heterogeneous reservoir, due to the existence of high permeability layers and micro-fractures, the air-foam system cannot effectively plug the high permeability layers or natural micro-fractures. Therefore, the single air-foam flooding technology cannot plug effectively. It is necessary to combine the polymer flooding technology to enhance the flooding effect. In this work, the plugging effect of the air-foam/polymer system on the heterogeneous permeability and fractured cores was studied to choose the suitable air- foam/polymers system for various reservoirs based on a physical model of heterogeneous permeability core and artificial-fractured cores. Finally, the enhance in the oil displacement efficiency of air-foam/polymer system was studied. The result show that 1) for plugging fracture with a permeability of 100x10(-3)mu m(2), a polymer with a medium molecular weight or above should be used; 2) under the same gas-liquid ratio, the higher the permeability, the better the foam plugging effect; 3) the greater the amount of foam injected, the higher the increment of the low-permeability oil recovery; 4) for oil layers with large interlayer differences or high permeability, further profile control measures need to be taken before foam injection, such as adjust the flow distribution so that the injected fluid can enter the low-permeability oil layer for oil displacement. This article provides a reference for upgrading the air-foam injection flooding technology.