Study Of Formation Parameters Change Effect On Filtration Based On Different Scales Of Simulation

Most of the oilfields in east China had entered the ultra-high water cut stage, which was an important stage and quite a few remaining recoverable reserves were developed in the stage. The change of formation macroscopic parameters because of long-term water injection caused the special seepage characteristics of reservoir fluids. The change of microscopic parameters was the internal reason of the change of macroscopic parameters. Therefore, the study of development rules and influential factors from the aspect of macroscopic and microscopic scales and the in-depth understanding of the seepage characteristics in the stage were conducive to the improvement of development effect and enhancement of ultimate oil recovery.On the basis of the analysis of the relative permeability curves, the effect of formation parameters change on seepage characteristics was investigated from different scales with the combination of the data in Shengli oilfield. Three dimensional network model was established in the process of microscopic network study. The effect of pore throat radius, shape factor and coordination number on macroscopic parameters was discussed and the comprehensive mode of formation parameters was developed. In reservoir numerical study, porosity, permeability and relative permeability curve were taken into consideration to improve the reservoir numerical simulator and the effect of single factor and comprehensive change on predicted oil recovery was researched. The internal relationship between formation microscopic parameter, macroscopic parameters and development rules was determined with the aim to understand the special static and dynamic characteristics in ultra high water cut stage.It was indicated in the microscopic study that the predominately influential factor of porosity was pore throat radius; the mainly influential factors of permeability were pore throat radius, homogeneity coefficient of pore throat radius, pore throat radius aspect ratio and coordination number; and the chief influential factors of relative permeability curve were homogeneity coefficient of pore throat radius, pore throat radius aspect ratio, wettability, pore throat shape and coordination number. The numerical simulation study results showed that permeability had great impact on oil recovery and the predicted oil recovery could decrease 1～3% while porosity had less influence on oil recovery and the predicted oil recovery could decrease about 0.5%; if the relative permeability curve was taken into account, the predicted oil recovery could increase 3～6%. Reservoir heterogeneity was the most important factor in the discussion of static and dynamic influential factors after taking the three parameters into account.