应用有机质降解程度法评价生物气源岩

Application of the Degration Degree of Organic Matter to Evaluating the Biogas Source Rock

研究表明，对厌氧阶段有机质降解程度的研究可以用于评价生物气源岩。通过对松辽盆地北部浅层20块生物气源岩样品常规有机地球化学及镜下观察得出，有机质降解程度与有机质成熟度无相关关系，但与有机质类型相关性极大，Ⅰ类生物气源岩有机质降解程度高达80%以上，Ⅲ类生物气源岩有机质降解程度低，一般低于60%。通过原始藻类有机质在产甲烷菌作用后细菌降解程度、生物气产率（用于计算有机质生物气转化率）实验表明，有机质细菌降解程度与有机质生物气转化率为正相关关系，当有机质降解程度达到80%时，有机质生物气转化率可达40%~50%左右；当有机质细菌降解程度小于10%时，有机质转化率仅为7%。通过有机质降解程度与有机质转化率的关系，可以确定现今未熟生物气源岩原始有机碳的含量。这对评价生物气源岩有重要的意义。

The Degration degree of organic matter during the anaerobic period of bacteria can be used as a method for evaluating the biogas source rock. The organic geochemical and microscope analyses for 20 samples in the north of Sonliao basin indicate that the degree of degration of organic matter is not correlated to the maturity of organic matter, while it is positively correlated to the type of organic matter. Degree of degration of organic matter is up to 80% for the type I biogas source rock but is always less than 60% for the type Ⅲ biogas source rock. The degration degree of organic matter and the production of biogas （it can be used to calculate the conversion ratio of biogas） of original algea before and after biogas simulation showed that the degree of degration of organic matter is positively correlated to the conversion ratio of biogas. When the degree of degration is up to 80%, the conversion ratio of biogas is 40%~50% and when the degree of degration is less than 10%, the conversion ratio of biogas is only 7%. The TOC of immature biogas source rock can be calculated approximately by the relationship between the degree of degration of organic matter and the conversion ratio of biogas.