摘要
针对北塘凹陷沙三段烃源岩岩样,从有机质丰度、有机质类型及有机质成熟度三方面,对岩石热解和有机碳、氯仿沥青“A”、沉积岩镜质体反射率、干酪根显微组分及类型等进行了有效测定,系统分析了沙三段烃源岩的有机地化特征。研究结果表明,沙三段烃源岩厚度可达1000~1500 m,厚度较大,有机碳含量(TOC)为0.4%~2.0%,含量总体较高,且主要以I、II型干酪根为主,有机质类型较好。此外,沙三段下部地层为北塘凹陷的主要生油层,其有机质丰度较高、转化效率较理想,腐泥质组和壳质组含量与烃源岩生烃潜力呈正相关,而镜质组含量和烃源岩的生烃能力呈反相关,进一步验证主要生烃母岩为腐泥组和壳质组。沙三段烃源岩主要凹陷属于晚期排烃,且排烃量大,勘探开发前景良好。
According to the source rock samples of the Third Member of Shahejie formation in Beitang De-pression,the organic matter abundance,types and maturity were discussed.The organic geo-chemical characteristics of source rocks in the Third Member of Shahejie formation were syste-matically analyzed through effectively determining the paralysis of rocks,organic carbon,chloroform asphalt“A”,vitrinite reflectance of sedimentary rocks,kerogen macerals and types.The results show that the thickness of source rocks in the Third Member of Shahejie formation is relatively large with nearly 1000-1500 m.The TOC content is 0.4%-2.0%,and the total content of source rocks is relatively high.The main types of source rocks are type I and type II kerogen,and the organic matter type is better.The lower part of the Third Member of Shahejie formation is the main source rock in Beitang Sag,with high organic matter abundance and ideal conversion efficiency.The content of sapropelic and crustal formations is positively correlated with hydrocarbon generation potential of source rocks,while vitrinite content is inversely correlated with hydrocarbon generation capacity of source rocks.It is further verified that the main source rocks are sapropelic and crustal formations.The main sags of source rocks in the Third Member of Shahejie formation belong to late hydrocarbon expulsion with large hydrocarbon expulsion and good prospects for exploration and development.
