东濮凹陷天然气生成模拟与煤成气的新证据

通过对东濮凹陷三种类型的气源岩加水高温模拟实验研究发现，石炭一二迭系煤生气能力是奥陶系灰岩的9倍，下第三系低有机质丰度的泥岩仅为煤的生气量的1／2，煤是东濮凹陷天然气最主要的气源岩；通过对模拟组分分析，煤生成的气体主要为甲烷含少量的重烃与CO2，低有机质丰度的泥岩与灰岩主要生成CO2；煤的模拟气体组分甲烷同位素值与W23井，M70井天然气甲烷同位素接近应该来源于石炭-二叠系煤系地层，灰岩与WG2井甲烷碳同位素接近，天然气来源于奥陶系灰岩地层。

NEW EVIDENCE FOR THE FORMATION SIMULATION OF NATURAL GAS AND COAL-TYPE GAS IN THE DONGPU SAG

Simulation ecperiment of high temperature with liquid on 3 types of gas-source rocks was conducted.It showed that the gas-forming capacity of Permian coal was 9 times higher than that of Ordovician limestone,and the gas-formin capacity of the mudstone with low organic abundance was 1/2 lower thn that of coal-producing gas.Therefore,coal was the main gas-source rock for the Dongpu sag.The analysis of component simulation revealed that coal-induced gas consisted mainly of methane with minor heavey hydrocarbon and CO_2.CO_2 was resulted chiefly from the mudstone and limestone with low organic abundance.The fact that the methane isotope of the simulating gas was similar to those of the W23 well,M70 well indicated that they were from the coal layers of the Carboniferous-Permian.The methane isotope of limestone was similar to that of WG2 well,indicating the natural gas came from the Ordovician limestone.