川东北不同含硫物质硫同位素组成及H2S成因探讨  

Stable sulfur isotopic compositions of different sulfur-containing materials and genesis of H_2S in northeastern Sichuan Basin

作　　者：谢增业[1] 李志生[2] 黄志兴[3] 王晓波[1] 马成华[2] 

机构地区：[1]中国矿业大学(北京),北京100083 [2]中国石油勘探开发研究院廊坊分院,河北廊坊065007 [3]四川石油管理局地质勘探开发研究院实验研究中心,重庆401120

出　　处：《地球化学》2008年第2期187-194,共8页Geochimica

基　　金：国家重点基础研究发展计划项目(2001CB209103)

摘　　要：自1995年川东北地区渡1井在飞仙关组获得高产的高含硫天然气以来,相继在该地区的罗家寨、滚子坪、渡口河、铁山坡、七里北、普光等构造发现高含硫大中型气田和含气构造,这些构造中的H2S含量一般分布在9%～17%之间。飞仙关组天然气中H2S的δ34S值主要分布在+10.3‰～+13.7‰之间,地层中硬石膏的δ34S值则分布在+11.0‰～+26.1‰之间,即天然气的δ34S值比硬石膏的δ34S值轻。针对不同含硫物质生成H2S的硫同位素分馏特征进行了一系列实验研究,包括硫化亚铁与盐酸反应,硫磺、硫酸钙分别与正己烷反应,泥灰岩加热生成H2S等,实验结果表明,无机反应生成的H2S的δ34S值均比反应物的重。理论上,在硫离子与氢离子结合生成H2S的反应过程中,S2-和H+通过离子的碰撞方式形成的34S2-与H+结合形成H2S的稳定性比32S2-与H+结合形成H2S的稳定性高。由此推测,若天然气中的H2S是由地层中硬石膏与烃类的反应生成的,那么H2S的δ34S值应该比硬石膏中的δ34S值重。综合各种因素认为单质硫与烃类的反应可能是川东北飞仙关组H2S形成最主要的原因。Since high natural gases production with high content H2S was gained Dul, northeastern Sichuan in 1995, some large and medium gas fields and gas in Feixianguan Formation of Well bearing structures with high H2S have been found such as Luojiazhai, Gunziping, Dukouhe, Tieshanpo, Qilibei, Puguang, in which the contents of H2S are generally from 9% to 17%. It is believed that the high content H2S results from the thermochemical sulfate reduction （TSR） by some scholars. The δ^34S values of H2S in natural gas of Feixianguan Formation range from ＋ 10.3‰ to ＋ 13.7‰, which are lighter than those in anhydrite （from ＋ 11.0‰ to ＋26. 1‰）. Based on sulfur isotopic fractionation of H2S generated by different sulfur-containing materials, a series of experiments are conducted such as ferrous sulfide reacting with hydrochloric acid, sulfur and calcium sulfate reacting with hexane respectively, heating marl and so on. The results show that the δ^34S values in inorganic reaction resultants are higher than the reactants. Theoretically, during the process of H2S formation, 34↑S2- is easier to combine H ＋ and forms more stable H2S, and has heavier isotopic composition than 32↑S2-. According to that conclusion, if the H2S is generated from the reaction of anhydrite with hydrocarbon, the δ^34S value of H2S should be heavier than that in anhydrite. It is concluded that the main process of H2S formation is the reaction of hydrocarbon with elemental sulfur in the Lower Triassic Feixianguan carbonate reservoirs in northeastern Sichuan Province.

关 键 词：硫同位素 实验 单质硫 硬石膏 黄铁矿 天然气 H2S 飞仙关组 四川盆地 

分 类 号：P597[天文地球—地球化学] P593[天文地球—地质学]