评价生物气生成量、生成期的碳同位素平衡法及其应用

The Carbon Isotopic Equilibrium Method of Evaluating the Biogas-generated Quantity and the Generation Period:its application

生物气的生成期对其成藏有至关重要的制约作用,但目前国内外尚缺少可信、有效方法来对此进行评价。针对这一难题,考虑到无论生物气的生成机理如何,转化前的有机质和转化后的残余有机质及产物的13C、12C的总量应该守恒,本文探索并建立了评价生物气生成量的碳同位素平衡法,并利用松辽盆地的实际分析数据,对这一评价方法(模型)进行了标定和应用。结果表明:Ⅰ、Ⅱ、Ⅲ型有机质累计产生物成因甲烷气的量分别约为193.94ml/g、175.64ml/g、161.71ml/g。区内源岩生物气的生成量约为385.4×1012m3;生物气的主要生成期在嫩江组沉积末期之前;区内生物气的可能资源量介于11.40×1011～24.8×1011m3之间。

The biogas generation period plays a very important role in its accumulation. But now there is not a creditable and effective method to appraise it. Aiming at this difficult problem, and considering it＇s a carbon isotope balance process, regardless of the formation mechanisms of biogenic gas. The 13C and 12C amount of initial organic matter and that of residual organic matter and other productions after generation should keep conservation. Carbon isotopic equilibrium method （model） is explored and established to assess biogenic gas in this paper, which is demarcated and applied according to the abundant analyzed data in Songliao basin. Results show that the accumulatively generated biogenic methane of Ⅰ, Ⅱ and Ⅲ types organic matters are 193.94 ml/g, 175.64 ml/g and 161.71 ml/g, respectively. The biogas-generated quantity of source rock in the research area is about 385.4 × 10^12 m3. The major period of biogenic gas generation occurs before the end of Nenjiang period. The possible biogas resource is between 11.40×10^11m^3and24.8×10^11m^3.