Geochemical characteristics of gases from the largest tight sand gas field (Sulige) and shale gas field (Fuling) in China
Geochemical characteristics of gases from the largest tight sand gas field (Sulige) and shale gas field (Fuling) in China
复制标题
DOI：
10.1016/j.marpetgeo.2016.10.021
复制
发表时间：
2017
影响因子：
4.2
通讯作者：
J. Dai;Y. Ni;D. Gong;Ziqi Feng;Dan Liu;W. Peng;Wenxue Han
中科院分区：
文献类型：
--
作者：
J. Dai;Y. Ni;D. Gong;Ziqi Feng;Dan Liu;W. Peng;Wenxue Han
对中国最大致密气田（苏里格）和页岩气田（涪陵）的烷烃气组分、烷烃气和CO2的稳定碳同位素、烷烃气的稳定氢同位素和再生气的氦同位素进行了详细的地球化学分析。对比研究表明，鄂尔多斯盆地苏里格气田致密气为煤源气，其碳、氢同位素呈正分布模式（δ13C1> δ13C2> δ13C3> δ13C4; δ2H1> δ2H2> δ2H3），碳、氢同位素随碳数的增加而增加。该气田的二氧化碳为生物成因，氦为地壳成因。涪陵页岩气田页岩气属于油成气，具有完全的二次蚀变成因（δ13C1< δ13C2< δ13C3; δ2H1< δ2H2< δ2H3）的碳、氢同位素反转，即碳数增加，碳、氢同位素降低。这种完全的同位素反转分布模式是由于高温下油气裂解、扩散等次生蚀变作用所致。在这种情况下，碳或氢的正同位素分布模式将随着温度的升高而转变为完全的同位素反转。二氧化碳是碳酸盐岩热变质作用的非生物成因，氦是地壳成因。
This study performed a detailed geochemical analyses of the components, stable carbon isotopes of alkane gas and CO2, stable hydrogen isotopes of alkane gas and helium isotopes of reproducing gas from the largest tight gas field (Sulige) and shale gas (Fuling) field in China. The comparative study shows that tight gas from the Sulige gas field in the Ordos Basin is of coal-derived origin, which is characterized by a positive carbon and hydrogen isotopic distribution pattern (δ13C1> δ13C2> δ13C3> δ13C4; δ2H1> δ2H2> δ2H3), i.e., the carbon and hydrogen isotopes increase with increasing carbon numbers. Carbon dioxide from this field are of biogenic origin and the helium is crust-derived. Shale gas from the Fuling shale gas field belongs to oil-derived gas which has complete carbon and hydrogen isotopic reversal of secondary alteration origin (δ13C1< δ13C2< δ13C3; δ2H1< δ2H2< δ2H3), i.e., the carbon and hydrogen isotopes decrease with increasing carbon numbers. Such complete isotopic reversal distribution pattern is due to the secondary alteration like oil or gas cracking, diffusion and so on under high temperature. In that case, positive carbon or hydrogen isotopic distribution pattern will change into complete isotopic reversal as the temperature increases. Carbon dioxide is of abiogenic origin resulting from the thermal metamorphism of carbonates and helium is crust-derived.