The Gudao and Gudong oil fields are non-compartmentalized structural regime. On the base of thesummarization of the main features of the fluvial reservoir in Gudao and Gudong oil filed, the occurrencemechanism of the remaining oil is carefully analyzed in terms of pore microstructure and the reservoirmacroscopic heterogeneity. The existing form and distribution of the remaining oil in different isotropicpore system and non-isotropic pore system are entirely summarized. We discuss the control factors of theheterogeneity on the distribution of the remaining oil in the plane, among layers and in layer. Theemphasis of the analysis is the function and effectiveness of the capillary force and gravity on differentrhythmicity and wettability reservoirs. The basic distribution law of the remaining oil in the fluvialreservoir is further summarized. The summarization and realization of occurrence mechanism anddistribution law of remaining oil in the fluvial reservoir are of guiding significance to this type ofreservoir. The Gudao and Gudong oil fields are non-compartmentalized structural regime. On the base of thesummarization of the main features of the fluvial reservoir in Gudao and Gudong oil filed, the occurrence mechanism of the remaining oil is defined analytically in terms of pore microstructure and the reservoir macroscopic The existing form and distribution of the remaining oil in different isotropicpore system and the non-isotropic pore system are entirely summarized. We discuss the control factors of theheterogeneity on the distribution of the remaining oil in the plane, among layers and in layer. Theemphasis of the analysis is the function and effectiveness of the capillary force and gravity on differentrhythmicity and wettability reservoirs. The basic distribution law of the remaining oil in the fluvialreservoir is further summarized. The summarization and realization of occurrence mechanism and distribution law of remaining oil in the fluvial reservoir are of cause significant e to this type ofreservoir.