石油学报 ›› 2010, Vol. 31 ›› Issue (5): 710-717.DOI: 10.7623/syxb201005002

• 地质勘探 • 上一篇    下一篇

四川盆地黄龙组烷烃气碳同位素倒转成因的探讨

戴金星  倪云燕  黄士鹏   

  1. 中国石油勘探开发研究院  北京  100083
  • 收稿日期:2010-04-27 修回日期:2010-05-27 出版日期:2010-09-25 发布日期:2010-11-30
  • 通讯作者: 戴金星
  • 作者简介:戴金星,男,1935年3月生,1961年毕业于南京大学地质系,现为中国科学院院士,中国石油勘探开发研究院教授级高级工程师,主要从事天然气勘探与研究工作。

Discussion on the carbon isotopic reversal of alkane gases from the Huanglong Formation in the Sichuan Basin, China

DAI Jinxing  NI Yunyan  HUANG Shipeng   

  • Received:2010-04-27 Revised:2010-05-27 Online:2010-09-25 Published:2010-11-30

摘要:

20世纪80年代后期至21世纪初,黄龙组成为四川盆地勘探开发热点,也是其主力储量层和产层,2008年天然气产量为68.1×108m3,占四川盆地年总产量的45.8%。黄龙组天然气的地球化学特征主要表现为氦同位素是典型的壳源型,R/Ra多数为0.01;硫化氢含量低,平均值为0.27%;属于干气,甲烷平均含量为96.71%,重烃气含量低,平均为0.71%。总的看来,黄龙组天然气是低碳优质能源。该烷烃气碳同位素发生倒转,即δ13C113C213C3。通过综合分析有机成因烷烃气碳同位素倒转的4种成因,确定黄龙组烷烃气碳同位素倒转的原因是其志留系烃源岩先期形成的具有轻的δ13C2的伴生气和后期形成的具有重的δ13C2的裂解气混合。

关键词: 四川盆地, 黄龙组, 烷烃气, 碳同位素, 倒转

Abstract:

The Huanglong Formation has become the exploration and development focus of the Sichuan Basin since the late 1980s, and it is also the main reservoir and producing formation in the Sichuan Basin. In 2008, it produced 68.1×108m3 natural gases,  accounting for more than 40% of the total output of the basin in that year. The geochemical characteristics of the natural gas from the Huanglong Formation are as follows: (1) Helium isotope is of the typical crustal type, and most of the R/Ra ratios are 0.01; (2) The content of hydrogen sulfide is very low, with the average of 0.27%, so the natural gas reserves in the Huanglong Formation are of low-carbon energy with high quality; (3) The gas is very dry. The average content of methane is 96.71% and the content of C2+ is very low, with the average of only 0.71%; (4) All the carbon isotopes of methane and ethane are in a reverse succession, i.e.δ13C113C213C3. The carbon isotopic reversal of natural gases from the Huanglong Formation was attributed to the mixing of the light associated gas generated by the Silurian source rock in the early stage and the heavy-oil-cracked gas formed in the late stage.

Key words: Sichuan Basin, Huanglong Formation, alkane gases, carbon isotope, reversal