四川盆地二叠系不同类型烃源岩生烃热模拟实验

通过对四川盆地二叠系不同类型烃源岩（泥质灰岩、沥青灰岩、泥岩和煤）在加水封闭体系下的热模拟实验，结果表明不同类型干酪根之间产气率明显不同。Ⅰ型干酪根的泥质灰岩总产气率最高（4 226m³/t_TOC），其次为沥青灰岩（2 445.5 mm³/t_TOC），煤岩总产气率最低（459.3m³/t_TOC），Ⅲ型干酪根的泥岩总产气率高于煤岩。泥质灰岩烃类气体产率仍然最高（765 m³/t_TOC），其次为泥岩（606.1 m³/t_TOC），沥青灰岩最低。泥岩烃类气体产率高于沥青灰岩，可能与沥青灰岩中除去烃类遭受热裂解外，碳酸盐分解生成大量非烃气体（CO₂）有关，从而造成总产气率高，而烃类气体产率却偏低的现象。这样，沥青灰岩生成的烃类主要来源于分散有机质热裂解，而不是灰岩本身。不同类型气源生烃对比结果表明，Ⅰ型干酪根的泥质灰岩或Ⅲ型干酪根的泥岩有利于低温生烃，而煤岩和分散有机质生烃历程长，有利于后期天然气生成与聚集保存。

Characterization of Gas Pyrolysates from Different Types of Permian Source Rocks in Sichuan Basin

Different types of the Permian source rocks (argillaceous limestone, asphaltic limestone, shale and coal) in Sichuan basin with 10mLwater were subjected to isothermal pyrolysis in a seal stainless steel reactor at temperatures ranging from 300℃ to 550℃ with 50℃ intervals for a duration of 24 h. Gas yield vary significantly for the different types of source rocks. Total gas yield from argillaceous limestone as type Ⅰ kerogen (maximum value=4 226 m³/t_TOC) is much higher than those from other source rocks, then from asphaltic limestone (maximum value=2 445.5 m³/t_TOC). Coal has the lowest gas yield (maximum value=459.3m³/t_TOC). The total gas yield from shale as type Ⅲ kerogen is more than that from coal. The maximum yield of total hydrocarbon gas is from argillaceous limestone (765 m³/t_TOC), then from shale (606.1m³/t_TOC). Similar yields of hydrocarbon gas from coal, crude oil and asphaltic limestone occur.The case that hydrocarbon gas yield from shale is higher than that from asphaltic limestone would be related to the generation of non\|hydrocarbon gas (i.e. CO₂) from thermal decomposition of carbonates besides hydrocarbons cracking in asphaltic limestone. Thus, the total gas yield from asphaltic limestone is relatively high, but the hydrocarbon gas yield comparatively low, suggesting that the hydrocarbon gas from asphaltic limestone would greatly stem from the thermal cracking of the dispersed soluble organic matter but not from the asphaltic limestone itself. By comparison among the gas yields from different source rocks, it can be concluded that argillaceous limestone as kerogen Ⅰ or shale as kerogen Ⅲ is in favor of hydrocarbon generation at low temperature, whereas coal and dispersed soluble organic matter have a long\|term period of hydrocarbon generation, and thus generation of hydrocarbon gas from coal and dispersed soluble organic matter is good for hydrocarbons accumulation later.