川北地区大隆组烃源岩地球化学特征与生气潜力初探

Geochemical Characteristics and Hydrocarbon Resource Potential of Dalong Formation Permian,Northeast Sichuan

岩石化学、有机地球化学和地质证据表明,四川盆地川北地区二叠系顶部发育一套富含Ⅱ型有机质的硅质岩段,厚度约为30m,有机碳含量均值为4.08%,热解生烃潜力均值为12.55mg/g,等效镜质体反射率值为1.2%～2.0%,是一套长期被忽视,但应该被充分重视的气源岩层段。根据排出和滞留于烃源岩的液态烃裂解成气两端元条件下的热成熟度与产烃率关系,计算平均生油强度为(17.6～22.3)×104t/km2,平均生气强度为(1.65～1.98)×108 m3/km2,总体评价为一套优质气源岩层段,生气潜力值得高度重视。

The data of rock element and organic geochemistry confirm that a set of organic rich siliceous ma- rine formation is distributed at the top of Permian in the northeast of Sichuan basin, whose thickness is 30 meters, and the sedimentary facies belongs to platform depression. The formation had type II organic mat- ter feature and the mean TOC and potential hydrocarbon ratio is 4.08% and 12.55mg/g, respectively, and the Ro is 1.2% -2.0%. Thus, this formation can be cognized as excellent source sediment formation with oil yields（17.6-22.3） × 104t/km2 and gas yields （1.65-1.98） × 108m3/km2. Much more exploration atten- tion should be paid to it.