1. Exploration and Development Research Institute of Daqing Oilfield Limited Company, Daqing 163712, Heilongjiang, China;
2. No.3 Oil Production Plant of Daqing Oilfield Limited Company, Daqing 163118, Heilongjiang, China

The exploration practice has proved that the Putaohua oil-bearing layer in Songliao Basin has superior accumulation conditions and characteristics of “sag-wide oil-bearing”, which is the main target of fine petroleum exploration. The remaining resource are mainly distributed in the high exploration area and its surroundings. The authors selected Aonan area located in the mature hydrocarbon source rock area as typical calibrated area, analyzed and depicted the source rock, reservoir and hydrocarbon accumulation using core, well logs and oil tests. It is believed that this area has three favorable geological conditions for hydrocarbon accumulation. Firstly, effective hydrocarbon source rock controls oil-gas distribution range. Secondly, delta front interbedded thin sand bodies can be good reservoir. Thirdly, assemblage of sand body with structure forms lithostratigraphic trap. Through comprehensive evaluation, the oil-bearing area of Aonan area is delineated as 256.3 km², and the resources volume is estimated as 5 057.1×10⁴ t, using the volume method and reservoir scale sequence method. The hydrocarbon migration and accumulation coefficient, recoverable factor, resource abundance are calculated, which represent key parameters of resource evaluation.