东濮凹陷上古生界生烃史及二次生烃时空差异性研究

东濮凹陷上古生界石炭—二叠系煤系地层是一个主要生气层系。研究认为,煤系烃源岩主要经历了海西—印支期深成变质作用、燕山期区域岩浆热变质作用及喜山期深成变质作用这3个热演化阶段和生烃过程。其中,喜山期深成变质作用对应的二次生烃期是主要生烃时期,生烃作用在时间和空间上具有分段性及主次性。古近纪中期（沙三—沙一段沉积期）以深洼陷带煤系烃源岩生气为主,斜坡带为次;古近纪晚期（东营沉积期）和新近纪,以斜坡带煤系烃源岩生气为主,地垒带为次。通过二次生烃时空差异性研究,明确了不同构造部位煤系烃源岩的成烃潜力,认为东濮凹陷北部地区二次生烃的潜量大于南部,其中中央隆起带北段—中段的文留、桥口、白庙等地区是最有利的勘探潜力区,西部斜坡带和孟岗集洼陷带也有一定勘探潜力。

Study on hydrocarbon generation history and space-time distribution variation of secondary hydrocarbon generation in Upper Palaeozoic formation of Dongpu Depression

The coal-bearing formation of Carboniferous-Permian is the principal gas-producing formation in Dongpu Depression.Study shows that the coal-bearing hydrocarbon source rocks undergo three thermo-evolution and hydrocarbon generation processes,including Hercynian-Indosinian deepseated metamorphism,Yanshanian regional magmatic thermal metamorphism and Himalaya deepseated metamorphism,among which the secondary hydrocarbon generation process is the major hydrocarbon generation process.In time and space,hydrocarbon generation function occurs periodically,primarily and secondarily.In middle Baleaogene（S3-S1 deposition period）,gas generation firstly happened in the coal-bearing source rock of deep depression belt and secondary in slope belt.In late Baleaogene（Dongying deposition period） and Neocene,gas generation mainly happened in slope belt and secondarily in horst belt.By studying the space-time distribution variation of secondary hydrocarbon generation,the hydrocarbon generation potential of coal-bearing source rock in different structures is made clear.It is thought that the secondary hydrocarbon generation potential of north area in Dongpu Depression is greater than that of south area.North interval to Wenliu,Qiaokou and Baimiao Region of middle interval in Central Uplift Belt are the most favorable exploration zones.There are some exploration potentials as well in West Slope Belt and Menggangji Subdepression.