Division Method of Dynamic Flow Units in Fluvial Reservoir at Ultra-high Water Cut Period

Abstract The heterogeneity of fluvial sedimentary reservoir is serious. The division of flow units in the early stage of development can provide a good guidance in the well pattern distribution and reservoir production. Due to the huge changes in the oil-water system in the long-term development reservoir, the flow units divided at the initial stage are difficult to guide the production when entering the ultra-high water cut period. Therefore, it is necessary to redefine the division indicators and methods of flow units, so as to provide support for the formulation of efficient regulation and control technology. Starting from the definition of flow unit, this paper establishes the percolation coefficient as the characteristic index of percolation capacity. Combined with the percolation characteristics of fluvial reservoir, the dynamic flow unit division method with percolation coefficient and water cut as division parameters is established. Through the division results of typical models of fluvial reservoir, it can be seen that the four types of flow units divided by the dynamic flow unit method in this paper can play a great guiding role in the later formulation of regulation and control measures. The verification of reservoir examples shows that the division results of dynamic flow units of fluvial facies can well reflect the remaining oil enrichment areas in the reservoir and classify the remaining oil enrichment areas. At the same time, the dynamic flow unit changes continuously with the development process, which can more clearly show the producing degree of each remaining oil enrichment area after the regulation and control measures. This provides a key support for formulating targeted and efficient reservoir development technique.