叠合盆地天然气的重要来源——分散可溶有机质

天然气形成具有多源性,以天然气直接母源赋存状态分类为基础,厘定了主要气源分散可溶有机质的概念。对分散可溶有机质赋存状态以及生成途径进行了分析,初步确定了作为气源岩的生气丰度下限,分析了生气潜力,认为分散可溶有机质是高演化阶段的最主要气源,具有广阔的勘探前景。分析了可溶有机质演化程度与气态烃转化率以及同位素的关系;指出分散型可溶有机质裂解气轻烃中环烷烃含量高,而聚集型可溶有机质裂解时链烷烃生成量较苯系物多,且裂解过程中没有环烷烃产物出现,这是因为无论是硅酸盐岩还是碳酸盐岩都对可溶有机质的成气演化起到了促进作用,因此分散可溶有机质比聚集可溶有机质生气潜力更为有效。结合实际地质情况,讨论了分散可溶有机质评价方法,使分散可溶有机质评价更具有可操作性。 

GAS GENERATION CHARACTER OF DISSIPATED SOLUBLE ORGANIC MATTER

The generation of natural gas has the character of owning various geological origins.In this paper,the defining process of dissipated soluble organic matter is summarized,the occurrence conditions and generation approaches are analyzed and the effective abundance lower limit is pointed out.It is believed that the dissipated soluble organic matter is the main gas source during the stage of high evolution degree and has broad exploration prospect.It was pointed out that the light hydrocarbon in cracked gas generated from dissipated soluble organic matter has much naphthenic hydrocarbon but it from accumulated soluble organic matter has no naphthenic hydrocarbon and has more paraffin hydrocarbon than benzene and naphthalene series.It was also attested that not only silicate rocks but also carbonate rocks have catalysis for the soluble organic matter generating gas,so the dissipated soluble organic matter is more potential than accumulated soluble organic matter to generate gas.Based on geology reality,the assessment method for dissipated soluble organic matter is indicated to make it operable to evaluate the potential of generating gas.