Origin of H_2S in Triassic Feixianguan Formation gas pools,Northeastern Sichuan Basin,China
Origin of H_2S in Triassic Feixianguan Formation gas pools,Northeastern Sichuan Basin,China
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发表时间：
2002
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通讯作者：
Wang Yi-gang
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作者：
Wang Yi-gang
四川盆地东北部宣汉-开峡地区三叠系飞仙关组含硫气藏目前埋藏深度为3000~ 4500 m，温度约100℃，含H2S 12%~ 17%。75%~ 88%CH4。研究区的H2S是由硫酸盐热化学还原（TSR）形成的与TSR伴生的硬石膏、H2S、S°和FeS 2的δ 34 S统计值分别为+30.4‰，+12.9 ‰，+19.1 ‰，部分交代硬石膏结核的等轴方解石的δ 13 C和δ 18 O分别为-7.26 ° C和-6.41 ° C。等长方解石中包裹体的温度范围为109 ~ 151℃，研究区飞仙关组的最高埋藏温度超过180℃，而最后一次构造抬升剥蚀时埋藏温度大于140 ℃，埋藏时间小于20 Ma，因此研究区油气藏中H2S含量小于20%。
The Triassic Feixianguan Formation sour gas pools at the Xuanhan-Kaixia n area in northeastern Sichuan Basin are buried to a depth of 3000～4500m presently,undergo temperature s of about 100℃and contain12%～17%H 2 S,75%～88%CH 4 .The H 2 S in the study area is formed by thermo chemical sulphate reduction(TSR)of the anhydrite underlying the gas r eservoirs.The statisticalδ 34 S values of the anhydrite,H 2 S,S°and FeS 2 ,associated with TSR,are +30.4‰,+12.9‰,+19.1‰,+19.4‰.Theδ 13 C andδ 18 O of the equant calcite partially replacing anhydr ite nodule is -7.26‰and -6.41‰.The h omogenization temperature of aque-ous fluid inclusions in the equant ca lcite ranges from 109℃to 151℃.The hi ghest burial temperature of the Feixianguan Formation in the study a rea was higher than 180℃,but the burial time was less than 20Ma when the burial temperature was greater than140℃as last tectonic uplift and denudaiton,so the H 2 S content is less than20%in the pools at the study area.