College of Earth Sciences��Jilin University��Changchun 130061��China

In terms of tectonic evolution and petroleum geological conditions of the Nepa- Botuoba Sub- basin and its adjacent sub- basins�� the accumulation conditions of the heavy oil were analyzed�� The studied area had plenty of oil and gas accumulation��but there were no developed source rocks�� It is a typical outside source accumula- tion��whose origins from thick high- quality source rock deposited in the adjacent sub- basins�� The shallow layer has favorable heavy oil reservoir conditions and poor sealing conditions��which benefits the thickening of hydro- carbon�� The multi- periods of structural compression not only uplifted the studied area drastically��but also crea- ted a series of fault zones and large- scale slope belt�� The structural compression also provided channel and suffi- cient power for migration of hydrocarbon to shallow layers�� Based on these conditions��the favorable accumula- tion zone of heavy oil was predicted��which provided direction for heavy oil exploration in Nepa- Botuoba Sub- basin��