The Songliao Super Basin in northeastern China

With several superimposed petroleum systems and a proven reserve of 200 billion bbl of oil and 160 TCF of gas, the Songliao Basin in northeastern China is considered a super petroliferous basin. This paper outlines the basin's tectonic units, its tectono-stratigraphy, and the essential elements of each petroleum system and reviews the distribution of hydrocarbon plays and opportuni-ties for future unconventional shale oil exploration. The Songliao Basin developed during an Early Cretaceous rifting event that resulted in localized petroleum systems with the limnic, swampy, coal-bearing Shahezi shale as the source rock for 156.4 TCF of gas discovered in synrift volcaniclastic reservoirs. Continued ther-mal subsidence during the Late Cretaceous resulted in two rapid flooding events, which resulted in the deposition of the organic -rich Qingshankou and Nenjiang Formations. The first member of Qingshankou shale (K2qn1), with a total organic carbon content ranging from 1 to 7 wt. % and a thickness of 50 to 100 m (165 to 330 ft), reached the oil window at 80 Ma and is the dominant source rock for the 103 billion bbl of oil and 4.4 TCF of gas dis-covered in sag-phase reservoirs. A total of 5 regional seal rocks and 10 stacked potential reservoir units have been identified within the basin, forming 5 hydrocarbon accumulation intervals from bottom to top: deep gas plays in the rift-phase sequence, lower, middle, and upper petroliferous plays in the sag-phase sequence, and shallow gas plays formed during the basin inversion phase.Additionally, shale oil is currently being produced from K2qn1, with estimated oil reserves of 95 billion bbl. The explora-tion history of the basin has evolved through structural traps, structural-stratigraphic composite traps, stratigraphic and volca-nic traps, and unconventional reservoirs. After more than 60 yr of production, the basin still has significant potential for enhanced oil recovery applied to conventional reservoirs and the explora-tion and production of its shale plays.