关于碳酸盐烃源岩的评价标准

通过模拟实验测得碳酸盐岩排烃下限值为TOC=0.06%～0.12%,并提出碳酸盐岩排烃下限值与碳酸盐烃源岩有机碳下限值应是两个概念。排烃下限值是烃源岩所固有的特性,不是人们自己设定的标准,而烃源岩有机碳下限值是一个评价标准,大小可以等于或大于排烃下限值,而不能小于排烃下限值。通过对碳酸盐岩有机质丰度、有机质类型、有机相和成熟度的研究,修正了过去碳酸盐岩只按Ⅰ类有机质的评价方法,而将碳酸盐岩有机质分为Ⅰ,Ⅱ₁,Ⅱ₂₃类,将碳酸盐烃源岩划分为4类,即很好烃源岩、好烃源岩、中等烃源岩、差烃源岩。未熟—成熟碳酸盐烃源岩有机碳下限值为0.2%～0.4%;高成熟—过成熟碳酸盐烃源岩有机碳下限值为0.1%～0.25%。 

DISCUSSION ON THE EVALUATION STANDARDS OF CARBONATE SOURCE ROCKS

The prescribed minimum of hydrocarbon expulsion of carbonate is measured to be TOC=0.06%-0.12% through simulating tests,and it is considered that its conception and total organic carbon lower limits of carbonate source rocks are different.The former is the origin character of rocks,not a giving standard.The total organic carbon lower limit of carbonate source rocks is a evaluating standard,and its value can be equal to or more than the prescribed minimum of hydrocarbon expulsion of carb(-onate),but not less than that.By means of the research of richness,type,facies and maturity of organic matter in carbonate source rock,the evaluating standards that carbonate had been considered as typeⅠkerogen have been amended as types Ⅰ,Ⅱ₁,Ⅱ₂ kerogen,and carbonate source rock has been divided as four types,that is,very good source rock,good source rock,fair source rock and poor source rock.The total organic carbon lower limits of carbonate source rock is 0.2% to 0.4% in immature and mature stages;and 0.1% to (0.25%) in high mature and past mature stages.