Research On Percolation Theory Of Cyclic Water Injection And Project Optimization

At present, the majority of oil fields in China are in period of medium or high water cut, it is difficult to enhanced oil recovery effectively applying conventional water injection way after the period of high water cut mining. Based on the principle of seepage mechanics, oil and water wells can be through implementing cyclic water injection, cyclic production, cyclic injection-production and other hydrodynamic methods, in process of cyclical changes water injection volume and the output, it take full advantage of the flexibility energy and the capillary force in reservoir and cyclical changes of pressure to cause penetration of different permeability zones and flow of residual oil in the retention area in state of conventional water injection, so that the oil of low-permeability layer and unswept area can be taken out, so as to achieve purposes of enhanced oil recovery and improving development effectiveness.In the paper, the east of North 3 in Sabei development area as a pilot area is studied, and the optimization of cyclic injection projects implemented in the pilot area is also studied by application of numerical simulation technology, which aimed at characteristics of residual oil distribution in high water cut and oil layers depositional features and based on percolation theory of cyclic water injection. Firstly, factors of cyclic injection-production impacting on the enhanced oil recovery are studied by establishment theoretical model of single-layer homogeneous, the impact of different permeability, effective thickness and water level on the recovery are optimized respectively, the relationship among pressure level, water level and interval injection cycle is also studied and variation of flow field in best influencing factors is described intuitively. Secondly, phased numerical model of multi-layer non-homogeneous is established through selecting a typical block from pilot area, four programs are optimized by simulating impact of different cyclic manner on development effectiveness and the indicators of optimization program are compared and described intuitively. Finally, three-dimensional phased geological model of the pilot area is established by collecting basic data of the pilot area. According to requirements of pilot area, optimal programs of cyclic injection-production for pilot area are optimized by simulating impact of different injection-production manners, interval water injection or production cycle and the proportion of water injection on development effectiveness. And variation of flow field in different cyclic injection-production manners is also described. It has important significance for improving oil recovery in high water cut stage and provides theoretical basis for improving development effectiveness.