东濮凹陷原油含硫化合物的分布特征及其应用

东濮凹陷盐湖相原油中杂原子化合物研究薄弱。采用高分辨率质谱结合色谱-质谱技术,对东濮凹陷盐湖相、淡水湖相原油中的含硫化物进行了检测。结果表明,原油中含有丰富的含硫化合物,S1和O1S1占绝对优势,咸水相原油富含S1类、淡水相原油相对富集O1S1类,指示O1S1/S1具有原始沉积环境指示意义。东濮盐湖相原油中的硫化物富含碳数为C27-35、C40的化合物,与原油中丰富的甾类、藿烷类与β-胡萝卜类化合物碳数相吻合,指示菌藻类、色素类生源的重要贡献。随成熟度增加,硫化物缩合度增加、烷基侧链碳数范围降低,相关参数DBE6/DBE12-S1、DBE3+6/DBE12+15+18-S1等可用于辅助评价原油成熟度。东濮低熟油含有丰富的低热稳定性硫化物,指示富硫干酪根和/或富硫大分子低温降解是低熟油形成的重要机制之一。

Characteristics and Significance of Organic Sulfur Compounds in the Crude Oils from the Dongpu Sag

Heteroatomic compounds in saline lacustrine in the Dongpu Sag are weakly documented. ESI FT-ICR MS combined with GC/MS were utilized to reveal sulfur compounds in the saline and freshwater lacustrine oils in the sag. Abundant sulfur compounds were detected and dominated by S₁ and O₁S₁ class species. It was observed that the saline lacustrine oils are relatively enriched in S₁ species while the freshwater lacustrine oils are abundant in O₁S₁ species, indicating the ratio of O₁S₁/S₁ is indicative of organofacies of source rocks. The saline lacustrine immature oils are composed of mainly sulfur compounds with carbon number to be C₂₇-C₃₅ and C₄₀,which is coincide with the carbon number of steroids, hopanoids and β-carotane, suggesting micro-organisms such as algas and bacterium as well as chromatophore to be important organic matter inputs when source rocks deposited. With increasing maturity, the DBE (double bond equivalent) values increased whereas the carbon number range of alkyl substitued decreased, and several relevant parameters were suggested to be maturity indicative. The saline immature oils are dominated by sulfur compounds with relatively low thermal stability, suggesting degradation of S-containing kerogen and/or sulfurous macromolecule under low temperature is one of the most important genetic mechanisms of immature oils in the area studied.