This paper studies the seepage law in heterogeneous reservoir to find out the flowing law and distribution of fluids at different development stages for revealing the internal relations between flow field and reservoir characteristics. Based on hydrodynamics theory and streamline cluster equation, this paper proposes that the seepage region which has similar fluid flowing law and reservoir characteristics is a micro- flow unit. The seepage flow mathematical model of the contribution rate of flow (CRF), nonuniform distribution curve of flow units (NDCFU) and the difference coefficient of flow intension (DCFI) has been established, and the principle for dividing high and low velocity flow area is based on the flow contribution rate of flow units. Simulation of constantrate water flooding dynamics in an injection-production unit of the inverted 5-spot pattern and plotting by means of streamline cluster equation show that the high velocity flow area had sufficient driving energy, occupying 53.7% of the entire flow unit area, but providing 61.7% of the total flow, and contributing most to the production. The low velocity flow area occupied 46.3% of the entire flow unit area, but only provided 38.3% of the total flow.

micro-flow units  /  seepage flow mathematical model  /  division of flow units  /  characteristic of planar flow