Abstract—

The carbon isotope composition of oil in the various regions of Tatarstan was found out to range from δ¹³C = –32.5 to –28.6‰. Oil in sedimentary rocks in the central part of the South Tatar Arch (STA) is characterized by a lighter carbon isotope composition (δ¹³C < –29‰) than oil in the southeastern STA slope (δ¹³C > –29‰), whose rocks are broken by deep faults. The oil of relatively heavy carbon isotopic composition is shown to be characterized by a high sulfur content, contains relatively much polar fractions, and is less catagenically mature that the oil with a relatively light carbon isotope composition. The source organic matter of oils, regardless of their carbon isotopic composition, in the South Tatar Arch was sapropelic material with an admixture of a bacterial component, which was transformed under reducing conditions when hosted in clay–carbonate sediments. The Devonian (D₂ gv) oil of the Bavlinskoye field (Well 475) in the southeast slope of the South Tatar Arch differs in composition from the other oils. Along with high contents of saturated (53%) and aromatic (36%) hydrocarbons, this oil is characterized by a relatively heavy carbon isotope composition and a sublinear curve of the isotope-fractional distribution of components. A similar distribution of components with a heavy isotope composition of the asphaltene carbon is typical the Devonian (D₃ psv) oil of the Abdrakhmanovskoye field (Wells 719 and 312) in the crest STA part, which generally has a relatively light carbon isotope composition and a contains low concentrations of polar fractions.

中文翻译：

---

南鞑靼拱门油田石油同位素地球化学碳组成特征

摘要-

鞑靼斯坦各地区石油的碳同位素组成范围为 δ ¹³ C = –32.5 至 –28.6‰。南鞑靼拱门 (STA) 中部沉积岩中的石油的特征是碳同位素组成 (δ ¹³ C < –29‰) 比 STA 东南斜坡的石油 (δ ¹³C > –29‰)，其岩石被深断层破坏。与碳同位素组成相对较轻的油相比，碳同位素组成相对较重的油的特点是硫含量高，极性部分相对较多，后生成熟度较低。南鞑靼拱门中石油的源有机质，无论其碳同位素组成如何，都是腐泥质材料和细菌成分的混合物，当存在于粘土 - 碳酸盐沉积物中时，在还原条件下转化。泥盆纪（D ₂gv) 位于南鞑靼拱门东南坡的 Bavlinskoye 油田（475 井）的石油成分与其他石油不同。除了饱和烃 (53%) 和芳香烃 (36%) 的高含量外，这种油还具有相对较重的碳同位素组成和组分同位素分数分布的亚线性曲线。具有沥青质碳重同位素组成的类似组分分布是典型的Abdrakhmanovskoye 油田（井 719 和 312）在 STA 部分的泥盆纪（D ₃ psv）油，其通常具有相对轻的碳同位素组成和a 包含低浓度的极性部分。