中文摘要：

渤海湾盆地是叠合在华北地台上的含油气盆地,随着勘探的深入发展,陆续发现了一些源于石炭系—二叠系的煤成气资源。笔者通过地球化学研究,认为具有成藏意义的煤成气是古近纪以来二次生烃过程中生成的,并且发现现今的低突起、斜坡带和洼陷带是煤成气生成和聚集有利区带。由于断裂发育,煤成气常与上覆沙河街组生成的油型气混合成藏,笔者通过统计各盆地Ⅰ、Ⅱ和Ⅲ型有机质生成的甲烷和乙烷碳同位素分馏情况,给出了煤成气和油型气鉴别图版,可以判别是否为二者的混合气。利用一级反应动力学,预测了5种构造单元煤成气生成率,发现隆起区和凸起区没有二次生气过程,洼陷带生气率已超过80%,斜坡带和低突起正处于快速生气期、并有轻质油生成。这些为进一步认识渤海湾盆地煤成气聚集和勘探潜力提供了依据。

英文摘要：

The Bohai Bay basin is a petroliferous basin superpositioned on the North China platform. With petroleum exploration growth, coal-derived gases generated from Carboniferous-Permian source rocks have been found in many places in the basin. By geochemical investigation the authors believe that the gases are products of secondary hydrocarbon generation after Paleogene, which can be accumulated in traps, and find that present low-uplift, slope and sag areas are favorable for the gas accumulation. As faults are developed everywhere, the coal-derived gases migrate up to Tertiary and mix with oil-type gases generated from the Shahejie Formation source rocks. By statistics of carbon isotope compositions of methane and ethane in natural gases generated from types Ⅰ, Ⅱ and Ⅲof organic matter, the authors postulate two plots for identification of the oil-type gas, coal-derived gas, and their mixed gas. By application of one order chemical kinetics, the productions of coal-derived gas secondarily generated from C -P source rocks are estimated for five different structural units. In conclusion, there are no secondary gas generations in the rise unit and uplift unit where no coal-derived gas accumulates. The gas production is over 80% from the resource rocks in sag belt unit which is a good gas kitchen for overlain traps. Coal- derived gases and light oils are quickly generated from the C-P source rocks in the slope and low-uplift units, which are favorable for gas exploration. This paper is useful in understanding coal-derived gas accumulation and exploration in the Bohai Bay basin.