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硫化氢形成机理对海相高硫天然气的勘探开发关系重大.研究的关键是直接测定自然界不同赋存状态(气、液、固)含硫物质的化学组成和同位素组成.为此,建立了利用MAT271型气体质谱计在线分析天然气中H_2S含量和不同含硫物质硫同位素组成的方法,开展了四川盆地包括烃源岩、储集岩、天然气、水溶气在内不同含硫物质的分析;对比分析结果表明,烃源岩中的含硫物质主要由BSR形成,天然气、水溶气和储集层中的含硫物质主要由TSR形成;对含硫天然气的碳同位素组成进行了系统分析,发现高含硫天然气甲、乙烷稳定碳同位素普遍呈倒转特征,其主要原因应与TSR有关;四川盆地不同层位的含硫物质硫同位素组成的地质实际分析表明,天然气中H_2S的硫同位素组成与同一层位或相邻层位的膏岩或卤水的硫同位素组成具有继承关系,表明H_2S形成和聚集具有自源-近源特征.
The formation mechanism of hydrogen sulfide is of great importance to the exploration and development of marine high-sulfur natural gas.The key of this study is to directly determine the chemical composition and isotopic composition of sulfur-containing substances in different occurrences (gas, liquid and solid) in nature.For this purpose, MAT271 gas mass spectrometer online analysis of natural gas H2S content and sulfur isotope composition of different sulfur compounds to carry out the Sichuan Basin, including source rocks, reservoir rocks, natural gas, water-soluble gases, including different sulfur-containing substances in the analysis; comparative analysis The results show that the sulfur-bearing substances in the source rocks are mainly formed by BSR, and the sulfur-containing substances in natural gas, water-soluble gas and reservoirs are mainly formed by TSR. The carbon isotope composition of sulfur-bearing natural gas is systematically analyzed and found to be high The sulfur isotopes of sulfur and methane are generally inverted, and the main reason should be related to TSR. The actual geological analysis of the sulfur isotope composition of sulfurous matter in different layers in the Sichuan Basin shows that the sulfur isotope composition of H_2S in natural gas is similar to that of the same layer The sulfur isotopic composition of the gypsum or brine of the bit or adjacent horizon has an inheritance relationship, indicating that the formation and accumulation of H_2S has the characteristics of self-near-source.