Using high-intensity water flooding relative permeability curve for predicting mature oilfield performance after long-term water flooding in order to realize sustainable development

Most of the mature oilfields are on the verge of being abandoned. Drilling infill wells or chemical displacement is a standard method to improve mature oilfield performance. But these methods are not economical. For the sustainable and economic development of mature oilfields, large displacement natural water flooding was applied for improving mature oilfield performance. After high-intensity water flooding, most of the mature oilfields are in high water-cut and high recovery stages, and it is difficult for performance prediction. Relative permeability is an important characteristic of multiphase flow in porous media and also an important parameter for dynamic prediction of high water cut stage. In this study, the ratio of the flow-through water flow to the pore area of the displaced cross-section, i.e., the displacement flux (P.A.), was applied to characterize the scouring intensity. Two types of relative permeability curves were obtained through high-intensity water flooding (HIWF) experiments, including one type of continuous relative permeability curve of different displacement fluxes (Type I HIWF relative permeability curve) and the second type of multiple relative permeability curves of different displacement fluxes under re-saturated conditions (Type II HIWF relative permeability curve). In addition, a twodimensional five-point pattern model was established to compare the calculation results of one conventional type of relative permeability curve and two types of HIWF relative permeability curve. Finally, a numerical model of a real reservoir in a mature oilfield was generated to test the method. The results demonstrate that using Type I HIWF relative permeability curve is fast and accurate to characterize the performance of the ultra-high water cut stag, which guides the application of high-intensity long-term water flooding in order to improving the ultimate oil recovery (IOR). So as to help the mature oilfields achieve economic and sustainable development.

Automated summary

This study utilized large displacement natural water flooding to obtain two types of relative permeability curves for mature oilfields, allowing for fast and accurate characterization of ultra-high water cut stage performance to guide the application of high-intensity long-term water flooding in order to improve ultimate oil recovery.