鄂西—渝东地区热史恢复及烃源岩成烃史

THERMAL HISTORY AND HYDROCARBON GENERATION HISTORY IN WESTERN HUBEI-EASTERN CHONGQING AREA

根据鄂西—渝东地区镜质体反射率数据进行的热史恢复结果表明：该区在晚二叠世初期达到最高古热流（可达68—78mW／m^2，地表热流），从晚二叠世初到现今古热流持续降低，在侏罗纪末期古热流平均为-54mW／m^2（地表热流）；鄂西—渝东地区中生界与新生界之间不整合面的剥蚀量可达1700—4000m。成烃史研究表明：鄂西—渝东地区志留系烃源岩在晚志留世—早二叠世进入生油高峰，在早-中三叠世进人生气期，中侏罗世晚期进入过成熟干气阶段，快速生烃时期是在晚志留世、二叠纪—中三叠世及早-中侏罗世；而二叠系烃源岩在早三叠世进入生油门限，于中-晚三叠世达到生油高峰，在中-晚侏罗世进入生气期，晚侏罗世晚期进入过成熟，快速生烃时期是在早-中三叠世及侏罗纪。

Thermal history reconstruction by using vitrinite reflectance data of western Hubei-eastern Chongqing area indicated that the maximum paleo-heat flow （68 - 78 mW/m^2） was reached in the early stage of Late Permian, and then decreased to present, and the paleo-heat flow at the end of Jurassic was averaged - 54 mW/m^2. The erosion thickness on the Mesozoic and Cenozoic unconformity varied from 1 700 m to 4 000 m. The Silurian source rocks of western Hubeieastern Chongqing area came into the oil-generating peak in Late Silurian-Early Permian, entered the gas-generation period in Early-Middle Triassic, and reached the overmature-dry gas phase in late Middle Jurassic. The hydrocarbon generation stage of the Silurian source rocks occurred during Late Silurian, Permian-Middle Triassic and Early-Middle Jurassic. The Penni- an source rocks came into the oil-generating peak in Middle-Late Triassic, entered the gas-generation period in Middle-Late Jurassic, and reached the overmature phase in late Late Jurassic. The hydrocarbon generation stage of the Permian source rocks occurred during Early-Middle Triassic and Jurassic.