|
|||||
|
|
| Carbon and hydrogen isotopic characteristics of natural gases from the Luliang and Baoshan basins in Yunnan Province, China | |
| 作者姓名： | XU Yongchang LIU Wenhui SHEN Ping WANG Wanchun WANG Xiaofeng Tenger YAN Yaomin & LIU Ruobin . Lanzhou Center of Oil & Gas Resources Institute of Geology and Geophsics Chinese Academy of Sciences Lanzhou China . Research Institute of Petroleum Exploration and Production SINOPEC Beijing China . South Branch of Petroleum Exploration and Production Company SINOPEC Kuming China |
| 作者单位： | XU Yongchang1，LIU Wenhui2，SHEN Ping1，WANG Wanchun1，WANG Xiaofeng1，Tenger1，YAN Yaomin3 & LIU Ruobin3 1. Lanzhou Center of Oil & Gas Resources，Institute of Geology and Geophsics，Chinese Academy of Sciences，Lanzhou 730000，China; 2. Research Institute of Petroleum Exploration and Production，SINOPEC，Beijing 100083，China; 3. South Branch of Petroleum Exploration and Production Company，SINOPEC，Kuming 650000，China |
| 基金项目： | 国家自然科学基金;国家重点基础研究发展计划(973计划) |
| 摘 要： | The Luliang and Baoshan basins are two small ba- sins in Yunnan Province. In the recent ten years or so, there have been found a number of natural gas pools of commercial importance in the two basins. Although the gas pools are small in size, the natural … |
| 收稿时间： | 28 October 2004 |
| 修稿时间： | 9 May 2005 |
Carbon and hydrogen isotopic characteristics of natural gases from the Luliang and Baoshan basins in Yunnan Province, China |
|
| XU Yongchang,LIU Wenhui,SHEN Ping,WANG Wanchun,WANG Xiaofeng,Tenger,YAN Yaomin & LIU Ruobin . Lanzhou Center of Oil & Gas Resources,Institute of Geology and Geophsics,Chinese Academy of Sciences,Lanzhou ,China, . Research Institute of Petroleum Exploration and Production,SINOPEC,Beijing ,China, . South Branch of Petroleum Exploration and Production Company,SINOPEC,Kuming ,China.Carbon and hydrogen isotopic characteristics of natural gases from the Luliang and Baoshan basins in Yunnan Province, China[J].Science in China(Earth Sciences),2006,49(9):938-946. | |
| Authors: | XU Yongchang LIU Wenhui SHEN Ping WANG Wanchun WANG Xiaofeng Tenger YAN Yaomin LIU Ruobin |
| Institution: | 1. Lanzhou Center of Oil & Gas Resources, Institute of Geology and Geophsics, Chinese Academy of Sciences, Lanzhou 730000, China 2. Research Institute of Petroleum Exploration and Production, SINOPEC, Beijing 100083, China 3. South Branch of Petroleum Exploration and Production Company, SINOPEC, Kuming 650000, China |
| Abstract: | The Luliang and Baoshan basins of Yunnan Province are two small-sized continental oil/gas-bearing sedimentary basins, which were developed at the bases of the Carboniferous and Devonian systems during the Late Tertiary, covering an area of 325 km2 and 254 km2, respectively. Since the 1990s, there have been discovered small-sized natural gas pools in these two basins. The natural gases are composed mainly of hydrocarbon gases, with nonhydrocarbons accounting for less than 2%. Of the hydrocarbon gases, methane accounts for more than 99%, and the components above C2 account for less than 0.2%. On the basis of previous studies of geological background, the composition of natural gases and their carbon isotopic composition, it has been defined that these two gas pools are of bacterial origin. In this work we have comprehensively measured the carbon and hydrogen isotopic composition of natural gases from these two basins and have gone into the details of the mechanism of gas generation. The δ 13C1 values of natural gases from the Luliang Basin are within the range of −72.1‰–−73.3‰, and the δDCH 4 values, −242‰–−234‰, indicating that the bacterial gas generation is dominated by the way of CO2 reduction. It has been evidenced that under continental-facies fresh water conditions there did occur the CO2 reduction as a process of bacterial gas generation. The δ 13C1 values of natural gases from the Baoshan Basin are within the range of −62.5‰–−63.5‰, and the δDCH 4, values, −252‰–−260‰. These isotopic characteristics are fallen into transitional phase of acetate fermentation and CO2 reduction as defined by Whiticar et al. (1986). An important discovery in the Luliang Basin is the carbon isotopic composition of ethane of purely biogenetic origin, i.e., its δ 13C2 values are within the range of −61.2‰–−66.0‰. These carbon isotopic values have been reported for the first time in China. As compared to the δ 13C2 values of less than −55‰ for the two cases encountered previously in the world, a significant difference is that in the latter two cases there are obvious signs of contamination caused by ethane of thermal origin. So it cannot be ruled out that the light δ 13C2 values are the result of isotope fractionation of ethane of thermal origin. The δ 13C2 values of natural gases from the Luliang Basin are all less than −60‰, and there is almost no possibility that ethane of thermal origin migrated vertically and horizontally into gas pools within this basins. This demonstrates that in the Luliang Basin the ethane, whose δ 13C2 values are within the range of −61.2‰–−66.0‰, is of purely biogenic, hence providing scientific evidence that ethane can be produced by the bacterial process. This is an important discovery in natural science, and also provides clues to the comprehensive study of the mechanism of formation of ethane. |
| Keywords: | bacterial gas carbon and hydrogen isotope CO2 reduction acetate fermentation |
| 本文献已被 CNKI 万方数据 SpringerLink 等数据库收录！ | |