Characteristics of source rocks from Carboniferous-Permian in Songliao Basin and its peripheral area, northeastern China.

In the Songliao Basin and peripheral area, the neopaleozoic tectonic layers are recognized as the folding and metamorphic basement of Mesozoic and Cenozoic basins for a long time, so they are neglected in the oil exploration. By the study in the field and laboratory for about 3 years, it indicates that there is no regional metamorphism in the Upper Paleozoic of the study area except for the dynamitic contact metamorphose and thermal metamorphism with various degree in some areas. The preliminary investigation indicates that it exists four source rock layers from Carboniferous to Permian in the area, from upper to lower including: Upper Permian (Linxi Formation, Suolun Formation), Middle Permian (Zhesi Formation,Wujiatun Formation), Upper Carboniferous-Lower Permian (Benbatu Formation, Amushan Formation), Lower Carboniferous (Baijiadian Formation, Hongshuiquan Formation). Among them, the Upper Permian (Linxi Formation) and Middle Permian (Zhesi Formation) spread widely in the area, the max monolayer thickness of the black muddy rock from which gets to several hundred meters and the accumulated thickness from several hundred meters to several kilometers. The main organic geochemical indices (the organic carbonate, the maturity and the type of kerogen) reflect the source rocks from the two formations get the rank of middle or good. The two formations are the main generating hydrocarbon layers in the Carboniferous-Permian of the Songliao and peripheral area, which shows the good prospect of oil and gas resource, would become the new strategic succeed strata in the northeast oil and gas exploration region of China.