松辽盆地南部中小断陷白垩系烃源岩成熟度综合评价——以彰武、昌图断陷为例

Comprehensive evaluation of Cretaceous source rock maturity in medium and small fault depressions in southern Songliao Basin: a case study of Zhangwu and Changtu fault depressions

武英利 朱建辉 倪春华 李贶

WU Yingli ZHU Jianhui NI Chunhua LI Kuang

中国石化 石油勘探开发研究院 无锡石油地质研究所, 江苏 无锡 214126

Wuxi Research Institute of Petroleum Geology, SINOPEC, Wuxi, Jiangsu 214126, China

应用镜质体反射率、烃转化率、OEP、甾烷异构化、藿烷等多项指标，对松辽盆地南部彰武、昌图断陷下白垩统沙海组—九佛堂组烃源岩成熟度特征进行综合评价，刻画烃源岩随埋深变化的动态热演化过程。松南地区南、北部断陷烃源岩的生烃门限存在显著差异，导致各断陷内的烃源岩现今所处的成熟演化阶段各有不同。南部彰武断陷烃源岩生烃门限深度大约在1 000 m，总体上沙海组烃源岩处于未熟—低成熟阶段；九佛堂组烃源岩上部处于低成熟阶段，而下部则处于成熟阶段。北部昌图断陷生烃门限深度大约在1 800 m，总体上沙海组下部、九佛堂组烃源岩处于低成熟—成熟阶段。南部断陷群九佛堂组中下部为有效烃源岩发育层段；而北部断陷群除九佛堂组为有效烃源岩发育层段外，沙海组中下部也是重要的烃源层段。

A comprehensive evaluation of the maturity of the source rocks in the Cretaceous Shahai and Jiufotang formations in the Zhangwu and Changtu fault depressions of the southern Songliao Basin was made using several indicators, including vitrinite reflectance, hydrocarbon conversion rate, OEP, sterane isomerization and hopanoid distribution. The dynamic evolution process of source rocks with burial depth was described. The hydrocarbon generation threshold is different between the southern and northern fault depressions, resulting in the various maturity stages of source rocks. The hydrocarbon generation threshold of source rocks in the Zhangwu Fault Depression in the south is about 1 000 m. Generally, the source rocks in the Shahai Formation are in the immature and low maturity stages. The source rocks in the upper Jiufotang Formation are in the low maturity stage, while those in the lower part are in the mature stage. The hydrocarbon generation threshold of source rocks in the Changtu Fault Depression in the north is about 1 800 m. Generally, the source rocks in the lower Shahai Formation and the Jiufotang Formation are in the low maturity and mature stages. The middle and lower parts of the Jiufotang Formation in the southern fault depressions developed effective source rocks. The Jiufotang Formation in the northern fault depressions developed effective source rocks, and the middle and lower parts of the Shahai Formation also contributed.

中国石化科技部项目 P12005

https://doi.org/10.11781/sysydz202002289