塔里木盆地天然气中丁烷的地球化学特征  

Geochemistical characteristics of butane gas in Tarim basin

作　　者：苗忠英[1,2] 陈践发[1] 郭建军[3] 张晨[1] 李伟[1] 王冠男[1] 

机构地区：[1]中国石油大学油气资源与探测国家重点实验室,北京102249 [2]中国地质科学院矿产资源所,北京100037 [3]中国石油勘探开发研究院海外中心,北京100083

出　　处：《中国矿业大学学报》2011年第4期592-597,共6页Journal of China University of Mining & Technology

基　　金：国家自然科学基金项目(40773039);国家科技重大专项(2008ZX0500-003)

摘　　要：为了研究母质类型、热演化程度和运移方向等成藏要素对丁烷地球化学特征的影响,统计分析了塔里木盆地天然气中丁烷组分和碳同位素的变化特征.结果表明:该区丁烷含量变化较大,体积分数在0.02%~28.9%之间,平均值为1.89%;丁烷碳同位素较稳定,台盆区主频在-30‰^-28‰之间;前陆区主频在-24‰^-22‰之间;油型气iC4/nC4值小于0.8,δ13C4轻于-27.5‰;煤型气iC4/nC4值大于0.8,δ13C4重于-25.5‰;处于较高热演化阶段的天然气δ13iC4-δ13nC4值大于0;不同输导条件下,沿运移方向iC4/nC4值具有不同的变化趋势,在碎屑岩输导层中沿运移方向iC4/nC4值减小;通过盖层散失或是在碳酸盐岩风化壳中运移的天然气,沿运移方向iC4/nC4值增加.天然气中的丁烷可以为油气成藏研究提供丰富的地球化学信息,对其组成和碳同位素特征的研究具有重要的理论和实践意义.In order to study the effects of matrix type, thermal evolvement and migrational di- rection on geochemistical characteristics of butane gas in Tarim basin, the changes of compo- nent of butane and carbon isotope were analyzed. The results demonstrate that the content of butane changes obviously, ranging from 0.02% to 28.9% in terms of volume, and the average value is 1.89 %. The carbon isotope composition of butane is relatively stable with the main frequency of δ^13 C4 between -30%0 and - 280/000 in platform areas and between - 24% and --220/000 in foreland area. The iC4/nC4 of oil-type gas is lower than 0.8, and OlaC4 is lighter than --27.5%o. Whereas the iC4/nC4 of coal-type gas is higher than 0.8, and δ^13aC4 is heavier than -- 25.50/000. The value of δ^13iC4-δ^13nC4 of nature gas at the stage of high-thermal evolution is more than 0. The value of iC4/nC4 of nature gases which migrate in clastic rocks decreases along mi- grational direction, but the counterpart of natural gas diffused from cap or migrating through weathering crust of carbonate increases. Thus, the component and carbon isotope of butane could offer abundant geochemical information about the accumulation of oil and gas which in turn plays a significant role on the research associated with butane.

关 键 词：塔里木盆地 正丁烷 异丁烷 碳同位素 天然气类型 运移方向 

分 类 号：TE122.1[石油与天然气工程—油气勘探]