鄂尔多斯盆地南部平凉组烃源岩特征及其成烃演化分析

CHARACTERISTICS AND HYDROCARBON GENERATION EVOLUTION OF PINGLIANG FORMATION SOURCE ROCKS, SOUTHERN ORDOS BASIN

倪春华 周小进 王果寿 杨帆 刘运黎

Ni Chunhua Zhou Xiaojin Wang Guoshou Yang Fan Liu Yunli

中国石油化工股份有限公司, 石油勘探开发研究院, 无锡石油地质研究所, 江苏, 无锡, 214151

Wuxi Research Institute of Petroleum Geology, SINOPEC, Wuxi, Jiangsu 214151, China

运用有机地球化学和有机岩石学相结合的方法,对鄂尔多斯盆地南部中奥陶统平凉组烃源岩进行了较系统的研究。研究区内平凉组烃源岩厚度平面分布特点为南厚北薄,纵向上岩性组合为上部灰岩、下部泥岩,下部烃源岩有机质丰度高于上部。烃源岩有机质类型属于Ⅰ—Ⅱ型,并以Ⅰ型干酪根为主。作为海相烃源岩成熟度研究的指标,海相镜质组反射率揭示研究区平凉组烃源岩成熟度为西低东高,现今主体处于成熟晚期—高成熟的演化阶段。通过PetroMod软件盆地模拟,并结合生烃热模拟实验结果综合分析,认为该区平凉组烃源岩于晚三叠世早期开始生油,中侏罗世末到达生油高峰,大规模生气期为早白垩世,具有一定的天然气勘探潜力。

Combining organic geochemistry together with organic petrology, the source rocks of the Pingliang Formation of the Middle Ordovician in the southern Ordos Basin have been systematically studied in this paper. Controlled by sedimentary facies, the thickness of hydrocarbon source rocks of the Pingliang Formation was characterized by horizontal distribution of thick in the south but thin in the north. The abundance of organic matter was characterized by longitudinal distribution of high in the below but low in the upper area. The types of organic matter were identified by type index of carbon isotope and the result reflected that there was mainly sapropelic kerogen. The marine vitrinite reflectance showed that maturity was higher in the east than in the west and it was mainly during the late-mature and the high-mature stage. The hydrocarbon source rocks of the Pingliang Formation worked as effective source rocks. Using the PetroMod software, combined with the hydrocarbon generation simulation experiments, it had been concluded that, source rocks of the Pingliang Formation began to generate oil in the Late Triassic, reached oil generation peak in the Middle Jurassic and generated gas in large scale in the Early Cretaceous. The muddy hydrocarbon source rocks of the Pingliang Formation have some natural gas potential in the southern Ordos Basin.

中国石油化工股份有限公司海相前瞻性研究项目(YPH08077)资助

https://doi.org/10.11781/sysydz201006572