Abstract: This paper suggested several main origins of low molecular weight organic acids in for-mation waters primarily.They are caused by the break of bonds of oxygenated groups fromkerogens which is during whole process of thermal-evolution of the kerogen and occurs main-ly in early maturation stage.They are originated from microbial degradation of crude-oil andits reaction with free oxygen dissolved in formation waters,mainly occured in zones near tothe ground or highly-opened ones over the reservoir where meteoric water can arrive,Theyare produced through redox reactions between the compounds containing high-valence ele-ments in minerals,such as Fe³⁺,SO₄^2- and so on,organic material,which is controlled mainlyby temperature.

Key words: formation water, organic acid, kerogen, thermal evolution, biodegradation, redox-reaction

摘要： 实验初步揭示了地层水中低分子量有机酸的主要来源:①由干酪根中含氧基团的断裂产生,伴随着干酪根热演化的全过程,主要发生在成熟早期阶段;②由地下水中微生物对原油的降解及游离氧气的氧化作用产生,发生在近地表或开启程度较高,有大气降水补给的地带;③由围岩矿物中的高价元素组成的离子或化合物,如Fe³⁺、SO₄^2-等,与有机质之间发生的氧化一还原反应所产生,反应受较高温度控制.

关键词: 地层水, 有机酸, 干酪根, 热演化, 生物降解, 氧化一还原反应