塔北、塔中天然气中烷烃同系物碳同位素组成系列倒转现象的解释  

The Explanation on the Turnover of Carbon Isotopic Compositions of Hydrocarbon Series of Natural Gases in the Northern and Central Tarim Basin

作　　者：王国安[1] 申建中[2] 何宏[3] 季美英[2] 

机构地区：[1]北京大学城市与环境系,北京100871 [2]中国科学院兰州地质研究所气体地球化学国家重点实验室,兰州730000 [3]中国矿业大学北京校区,北京100083

出　　处：《沉积学报》2002年第3期482-487,共6页Acta Sedimentologica Sinica

基　　金：国家自然科学基金项目 (批准号 :40 1 730 2 3);塔里木盆地"九五"科技攻关项目资助

摘　　要：塔里木盆地塔北、塔中地区天然气中烷烃气碳同位素组成序列存在着局部倒转现象 ,通过对此的研究和解释 ,初步认为塔北、塔中天然气中的烷烃气可能是以有机成因气为主 ;轮台构造单元天然气烷烃系列的δ13 C3 >δ13 C4倒转可能是混入了偏腐泥型的烷烃气体 ;轮南低凸起构造单元的天然气烷烃同系物碳同位素组成序列正常 ,天然气来源单一 ;塔中地区天然气按CH4 和C2 H6的碳同位素组成特征可分成两组 ,可能代表了两种不同的成因类型。The carbon isotopic compositions of hydrocarbon series were measured from natural gases in the Northern and Central Tarim Basin. Many local turnover phenomena, e.g. δ 13C 1>δ 13C 2>δ 13C 3 or δ 13C 1>δ 13C 2>δ 13C 3>δ 13C 4, exist in the carbon isotopic compositions of hydrocarbon series. They suggests that hydrocarbons of the natural gases may be mainly biogenic in the Northern and Central Tarim Basin. Most of natural gas samples have the turnovers of δ 13C 3>δ 13C 4 from the Northern Slope Zone in the Luntai uplift, and the cause of the turnovers may be that these natural gases were mixed less amount of sapropelic hydrocarbons. According to δ 13C 1 values of natural gases and whether they have the δ 13C 1>δ 13C 2 turnover, natural gases in the Central Tarim Basin can be divided into two groups. Natural gases of the first group have heavy δ 13C 1 values, between -21.1‰～ -30.7‰,and the δ 13C 1>δ 13C 2 turnover, such as Tz26(O)well, Tz103(C Ⅱ)well and Tz103(C Ⅲ)well; The others have light δ 13C 1 ,δ 13C 2 values,with -41.0‰～-43.7‰,and -38.8‰～-39.6‰, respectively, without the δ 13C 1>δ 13C 2 turnover, such as T24sp-3 (C Ⅲ),Tz4-8-30 (C Ⅲ), Tz-1(O)and Tz45(O)well. It may suggest that less amount of abiogenic hydrocarbons was contained in natural gases of the first group, and that natural gases in the Central Tarim Basin have two genetic types. All the natural gases do not exist turnover of carbon isotopic compositions from the Lunnan Lower-uplift, suggesting that they may come from the same source.

关 键 词：天然气 烷烃同系物 碳同位素 组成序列 倒转 塔里木盆地 有机成因气 

分 类 号：P618.130.1[天文地球—矿床学] TE12[天文地球—地质学]