火成岩对石炭-二叠系煤岩二次生烃作用影响的研究

华北地区石炭-二叠系煤系具有良好的油气勘探前景,已发现油气的区域大多发现了侏罗纪闪长玢岩和煌斑岩,石炭-二叠系烃源岩曾在三叠纪或侏罗纪达到生烃门限,但是缺乏成藏条件,油气没有得到保存。渐新世以来,煤系烃源岩得到深埋进入二次生烃演化阶段,并且形成了以煤成气为主、少量轻质油的油气聚集,该煤成气具有异丁烷/正丁烷、环烷烃和芳香烃含量高、乙烷碳同位素重等特点。作者以为在生烃过程中存在侵入岩与烃源岩的相互作用,并且利用热模拟实验的方法考察了煤岩在与侵入岩接触的条件下二次生烃过程,发现气态烃产率明显增加、并且气态烃组成与钻井产出的天然气相似,认为与闪长玢岩和煌斑岩确实参与了煤系烃源岩的生烃作用,指出在评价石炭-二叠系油气勘探时应当考虑这个因素。

Thermal stimulation of hydrocarbon generation from the Carboniferous-Permian coal with igneous rock existing conditions.

There is great oil and gas perspective in the coal series of Carboniferous-Permian in the North China. Up to now where oil and gas is discovered, where shallow intrusive rocks are also drilled. The intrusive rocks are mainly diorite porphyrite and lamprophyre. Hydrocarbon source rocks including coal in the Carboniferous-Permian came into hydrocarbon generation threshold primarily during Triassic and Jurassic, but the oil and gas were not preserved because the accumulation condition was not available. Since Eocene the source rocks have been buried bellow the threshold of second hydrocarbon generation, coal-derived gas and some light oil have been accumulated in the Gubei, Suqiao and Linqing areas. The gas is geochemically special with high ratio of isobutene/butane, high content of cycloparaffin and aromatics, heavy carbon isotope composition. The authors believed that interaction between the intrusive rocks and source rocks impressed the second generation of oil and gas from the coal series, conducted a series of thermal simulation on hydrocarbon generation from the coal sample and from the coal mixed with the diorite porphyrite or with lamprophyre, and discovered that the productions of gaseous hydrocarbon were increased notably, the gaseous hydrocarbon compositions were similar to those produced from the drilling wells. They concluded that the intrusive rocks (such as diorite porphyrite and lamprophyre) involved the hydrocarbon generation from the coal series, and suggested that coal-derived gas exploration on the Carboniferous-Permian should consider the factor of intrusive rocks on hydrocarbon generation from the coal-series source rocks.