含铁矿物对高成熟有机质有水体系热解生气的影响

为了探讨含铁矿物对水—有机质生气的影响，基于黄金管热模拟装置，选用了高熟干酪根样品开展了3组有水体系（干酪根+水、干酪根+黄铁矿+水、干酪根+磁铁矿+水）的恒温热解实验。气体产物的定量分析结果表明，黄铁矿和磁铁矿的加入均导致干酪根在有水体系下气态烃产率一定程度的降低。比如，水—黄铁矿体系和水—磁铁矿体系在Easy%R_O=3.08%时CH₄产率相比单独有水体系分别降低8.5 mL/g_TOC和13.3 mL/g_TOC。水—黄铁矿体系CO₂产率及碳稳定同位素值明显高于单独有水体系和水—磁铁矿体系，含铁矿物（尤其是磁铁矿）加入的热解体系的H₂S产率明显低于单独有水体系。气体组成分析结果表明，含铁矿物的加入明显提高了烃类气体的干燥系数，同时导致异构烷烃相对含量的降低。水—磁铁矿体系气体产物氢同位素值相对低于单独有水体系，表明磁铁矿的加入促进了早期H₂的生成而与有机质之间发生了加氢作用。这些结果表明，含铁矿物的加入可能抑制了碳正离子的反应，水—有机质的加氢生气可能主要是自由基反应。

Effect of iron-bearing minerals on gas generation from pyrolysis of high-mature organic matter in hydrothermal conditions

In order to ascertain the effect of iron-bearing minerals on gas generation from water-organics reactions, three groups of isothermal pyrolysis involving a high-mature kerogen (kerogen + water, kerogen + pyrite + water, kerogen + magnetite + water) were conducted in hydrothermal conditions by a gold-tube system. Through determination of the yields of gas products, it is indicated that the presence of pyrite and magnetite both led to a certain decrease in the yields of hydrocarbon gases. For instance, the methane yields at Easy%R_O of 3.08% in hydrothermal experiments with pyrite and magnetite are about 8.5 and 13.3 mL/g_TOC lower than that in pyrolysis with only water. The yield and carbon isotopic ratios of CO₂ in pyrolysis involving water and pyrite are evidently higher than those in pyrolysis involving only water and involving water and magnetite. The H₂S yields in hydrothermal experiments with Fe-bearing minerals (especially magnetite) are much lower compared with those without minerals. The analysis of gas compositions shows that the presence of pyrite apparently resulted in the increase of gas dryness and the decrease of relative content of isomeric hydrocarbons. The hydrogen isotope of the gas product of the water-magnetite system is relatively lower than that of the water-only system, indicating that the addition of magnetite promoted the formation of early H₂ and hydrogenation occurred with the organic matter. These results indicate that the addition of iron-bearing minerals may inhibit the carbocation reaction, and the hydrogenation of water-organic matter may be mainly a radical reaction.