天然气地球化学数据的获取及应用

天然气地球化学研究已成为天然气藏勘探开发的重要基础工作。由于气源的混合性和天然气化学组成和同位素组成影响因素的多样性使得天然气藏的形成过程极为复杂 ,同时也给天然气地球化学研究带来了极大的困难和严格的要求 ,故而 ,获取精确的地球化学分析数据无论对科学研究还是对气藏的勘探开发来说都非常重要。不同成因的天然气类型和同一源岩不同演化阶段生成的天然气具有不同的化学组份和不同的稳定同位素特征。根据气体化学组份和稳定同位素特征可初步确定天然气的成因类型。在天然气类型确定后 ,利用天然气碳同位素与 Ro 之间的关系式可以确定天然气的成熟度。而系列碳同位素之间会存在差异 ,存在差异的原因可能是多种多样的。稀有气体可作为判识天然气来源的一个辅助指标 ,用此指标可鉴别天然气中是否有深部气体的混入。当确定天然气中无深部气体混入时 ,可利用4 0 Ar/ 36 Ar比值对烃源岩的年代做出初步的估算。应用地球化学参数在解释天然气形成特征时 ,必须结合实际地质背景进行

THE GAINING AND APPLYING OF DATA IN NATURAL GAS GEOCHEMISTRY STUDY

Natural gas geochemistry study has become an important basic work in the exploitation of natural gas. Because of the mixing of gas sources and the multiformity in the natural gases chemical composition and isotopic composition, the forming process of gas pool is very complex. It is important that take accurate geochemistry analysis data in natural gas geochemistry study. Natural gases formed by different types and different evolvement stage of source rocks have different chemical composition and isotopic characteristics. According to these, we can confirm the forming type of natural gases. After these, using the relation between natural gas carbon isotope and R o, we can make sure the maturity of natural gas. There are many reasons making the variety of the carbon isotope series. Being an assistant index to judge the natural gas resource, noble gas can distinguish whether natural gas mixed by deep gas or not. When it is made sure that the natural gas has been mixed by deep gas, the 40 Ar/ 36 Ar value is used to estimate the age of source rock. When applying these geochemistry indexes to explain the forming characteristics of natural gases, we must combine the geological background.