Improved understanding of the hydrogen sulfide (H₂S) origins is of significant importance for petroleum exploration, exploitation and refinement due to it being highly toxic and corrosive. H₂S was discovered from the Qianjiang Formation (Eq) in the northern area and Xinggouzui Formation (Ex) in the southern area of the Qianjiang Depression, Jianghan Basin, China. The sulfur isotopic compositions of H₂S, water-dissolved sulfates and oils and chemical compositions of volatile organic sulfur compounds (VOSCs) in natural gas as well as molecular and stable carbon isotopic compositions of oil and gas samples were measured to decipher the specific generation pathways of H₂S. The conventional wisdom relays on bacteria sulfate reduction (BSR) for producing H₂S because of the current low thermal regime (<80 °C). Crude oils, H₂S and water-dissolved sulfates are progressively enriched in ³⁴S. The δ³⁴S values of H₂S are around 12.0–32.0‰ lower relative to that of the dissolved sulfates and 0.8–24.0‰ greater relative to that of crude oils. This indicates that the current major contribution of H₂S is actually related to BSR according to the S isotopic fractionation levels in BSR. The secondary contribution of H₂S is attributed to be thermogenic mainly by thermal cracking alteration of organic matters (TCA). This clue is provided by the distribution patterns of VOSCs in natural gas rather than S isotope of crude oils, H₂S and water-dissolved sulfates due to the limited input of TCA-associated H₂S. The Eq TCA-associated gases are significantly enriched in thiols, sulfides, and alklyated thiophenes, the Ex BSR-associated gases contain mainly thiols and a little bit sulfides and alkylated thiophenes. The relevant early-matured Eq oils are also rich in labile organosulfur compounds, favoring the generation of VOSCs by TCA. VOSCs detected on the artificially pyrolyzed gaseous products of Eq rock and oil both show the identical distribution patterns as those of Eq natural gas samples, supporting the occurrence of TCA-associated H₂S in the Eq reservoirs. The positive correlation between i-C₄/n-C₄ and H₂S concentration for Eq gases indicates the catalytic effects of clays, promoting the generation by non-biological processes within the low thermal regimes. This study presents a novel method to clarify the origins of H₂S by VOSCs in natural gas and improves our understanding of H₂S generation pathways within low-temperature regime in nature.

由于硫化氢（H ₂ S）具有剧毒和腐蚀性，因此对于石油勘探，开发和精炼至关重要。H ₂ S是从江汉盆地潜江De陷北部地区的钱江组（Eq）和南部地区的兴狗嘴组（Ex）发现的。测量了天然气中的H ₂ S，水溶性硫酸盐和油的硫同位素组成以及挥发性有机硫化合物（VOSCs）的化学组成以及油气样品的分子和稳定碳同位素组成，以判别特定的生成H _2的途径S.对细菌硫酸盐还原（BSR）用于生产H中的传统智慧继电器₂，因为当前的低热状况（<80℃）的S上。原油，H ₂ S和水溶解的硫酸盐逐渐富集在³⁴ S的δ ^34级的H 2 S的值_2个S分别围绕12.0-32.0‰降低相对于溶解的硫酸盐和‰更大相对于0.8-24.0的原油。这表明，根据BSR中的S同位素分馏水平，当前H ₂ S的主要贡献实际上与BSR有关。H ₂的次要贡献S主要由于有机物的热裂解改变（TCA）而具有热源性。这是由于天然气中VOSCs的分布方式，而不是原油，H ₂ S和水溶硫酸盐的S同位素，这是由于TCA相关的H _2的输入有限。S. Eq TCA相伴的气体中富含硫醇，硫化物和烷基化的噻吩，而Ex BSR相伴的气体主要包含硫醇，少量硫化物和烷基化的噻吩。相关的早熟Eq油还富含不稳定的有机硫化合物，有利于TCA生成VOSC。在Eq岩石和石油的人工热解气态产物中检测到的VOSC均显示与Eq天然气样品相同的分布模式，这支持了Eq储层中TCA相关H ₂ S的发生。i -C ₄ / n -C ₄与H ₂正相关Eq气体的S浓度表明了粘土的催化作用，在低热范围内促进了非生物过程的产生。这项研究提出了一种新颖的方法，以澄清天然气中VOSCs对H ₂ S的起源，并增进我们对自然界低温条件下H ₂ S生成途径的了解。