高成熟阶段膏岩等盐类物质在烃源岩热解生烃过程中的催化作用

Catalytic Action of Sulphate Evaporates in Pyrolytic Gas Generation of Source Rocks

东营凹陷民丰地区沙四段是典型的盐湖相沉积,也是重要烃源灶和天然气产层。为了查明民丰地区深层天然气成因,采用高压釜封闭体系实验模拟了高成熟盐湖相烃源岩的天然气生成过程。实验结果表明:碳酸盐、硫酸盐、氯化盐对烃源岩热解生成天然气有强烈的催化作用,550℃时气态烃产率分别增加了35%、77%和46%。热模拟气与民丰天然气的C6轻烃组分比较发现,膏盐等盐类物质改变了气态烃产物中各单组分化合物的生成路径,影响了气态烃产物的组成。上述盐类物质参与的烃源岩热解过程所生气态烃的组成与民丰天然气最接近。这一结论对认识高成熟盐湖相天然气的生成过程及民丰地区天然气成因有重要意义。

It is observed that the natural gas is from the saline lacustrine source rock in the Minfeng area, Dongying Sag. In order to study the origin of the natural gas, this paper conducts a series of thermal simulation, finds that carbonate sulfate and chlorate can increase the hydrocarbon gas yield. The increases of hydrocarbon are 35%, 77% and 46% , respectively, at 550℃ when the three evaporates are mixed with the source rock. By comparison with the composition and parameter of the light hydrocarbon, it is conclu- ded that evaporates could change the generating ways of chemical compounds and promote the evolution of organic matter. Furthermore, the composition of gaseous hydrocarbons generated from the source rock with evaporates are more similar to those of natural gases found in the Minfeng area. In view of above, the conclusion of the thermal simulation has an important effect on the recognition of the saline lacustrine hy- drocarbon generation and the natural gas origin in the Minfeng area.