Quantitative Characterization of Remaining Oil Distribution in Fractured Low-Permeability Reservoir

Matrix and fractures are different seepage systems. When waterflooding starts, oil-gas-water interaction mechanism, remaining oil distribution characteristics and fluid flow characteristics are more complex. This paper takes block X of Daqing oilfield as an example, the dual-porosity and dual-permeability geological model is established by using the drilling, logging and seismic data to simulate history matching. The distribution characteristics of the vertical and plane remaining oil are studied quantitatively. Rmaining oil types are characterized quantitatively according to the geological characteristics, well pattern characteristics and dynamic development characteristics. The research shows that the vertical remaining oil is mainly concentrated in class III reservoir, accounting for 40.96%; the plane remaining oil is mainly concentrated in the main channel sand and non-main channel sand, accounting for 56.58% and 31.29% of the total remaining reserves respectively. Class I oil layers are dominated by plane interference remaining oil, accounting for 41.82%; Class II oil layers are dominated by interlayer interference and plane interference remaining oil, accounting for 22.16% and 35.84% respectively; Class III oil layers are dominated by mainly injection production imperfect remaining oil, accounting for 61.21%. This paper can provide guidance for the potential remaining oil recovery accurately in fractured low-permeability reservoir.