Accumulation threshold and exploration potential of deep basin oil in the Songliao Basin

To further understand the accumulation mechanism and distribution rules of deep basin oil, the laboratory physical simulation experiment is conducted for water-sealed oil in sand columns of different grain sizes, and the water-sealed oil mechanism and the accumulation threshold of deep basin oil are analyzed. Stable deep basin oil can be formed under laboratory conditions. The accumulation threshold of deep basin oil mainly depends on the pore throat radius of oil-bearing sand layer as well as the oil/water interfacial tension and strata dip under such conditions. The accumulation threshold and its main controlling factors of the deep basin reservoir in the Fuyang oil layer are studied, and the prediction model of deep basin reservoir boundaries is established: the porosity is less than 11%, the permeability is less than 1×10−3 μm2, the largest pore throat radius is less than 6.2 μm, and the burial depth is 1800-2100 m, located at the lower positions of syncline or slope, and good source rock in Qing-1 Member is developed, with obviously abnormal pressure. Three “sweet spot” areas favorable for deep basin oil in the Songliao Basin are determined, namely south Liangjing area, east Haituozi area, and west Qianʹan area. The predicted deep basin oil potential in these three areas is 0.317 billion tons. The total proved resources of deep basin oil in the Songliao Basin are 1.575 billion tons, with good exploration potential.