气候变化领域集成服务门户(CCPortal): Hydrogen isotopic responses to thermochemical oxidation of light hydrocarbon gases in deep clastic reservoirs of the Junggar Basin, China

CCPortal

DOI	10.1016/j.chemgeo.2020.120052
	Hydrogen isotopic responses to thermochemical oxidation of light hydrocarbon gases in deep clastic reservoirs of the Junggar Basin, China
	Kang, Xun; Hu, Wenxuan; Tan, Jingqiang; Li, Zhongping; Xiang, Baoli; Wang, Jian; Wang, Xiaolin
通讯作者	Hu, WX (通讯作者)，Nanjing Univ, Sch Earth Sci & Engn, 163 Xianlin Ave, Nanjing 210023, Peoples R China.
发表日期	2021
ISSN	0009-2541
EISSN	1872-6836
卷号	563
英文摘要	The occurrence of high-valence Mn/Fe oxides in deeply buried oxidized reservoir rocks promotes thermochemical oxidation of hydrocarbons (TOH). This study aimed to better understand this process and its effects on hydrogen isotopes via sampling natural gases from the Lower Triassic red beds with depths of >3.5 km in the Junggar Basin, NW China. The gas compositions, hydrogen and carbon isotopes of C-1-C-4 alkanes, and carbon isotopes of carbon dioxide were analyzed. The gases are almost mature thermogenic gases generated by sapropelic kerogen from the deeper Lower Permian source rock. The hydrocarbon gases display a unique reversed trend of delta H-2(CH4) > delta H-2(C2H6) < delta H-2(C3H8) > delta H-2(n-C4H10), whereas the carbon isotopic compositions (delta C-13) of C-1-C-4 alkanes mostly follow the normal trend of delta C-13(CH4) < delta C-13(C2H6) < delta C-13(C3H8) < delta C-13(C4H10). The average delta C-13 values of C-1-C-4 increased by 10.0 parts per thousand, 6.0 parts per thousand, 4.4 parts per thousand, and 5.1 parts per thousand, respectively, compared with the initial gases from source rocks, and exhibit a gradually declining trend. In contrast, the delta H-2 values of C-1-C-4 increased more from those of normal thermogenic gas, and the size of the H-2-enrichment varies, eventually resulting in the unique reversals. The delta H-2 and delta C-13 increments of methane are much higher than those of C-2-C-4. The reversals cannot be explained by current models for hydrocarbon gas generation, such as mixing of gases from different sources and thermal maturities. Instead, the results are consistent with a model where TOH caused a systematic C-13- and H-2-enrichment of C-1-C-4 after hydrocarbons charged the reservoir beds enriched in high-valence Mn/Fe oxides. Increase of C-1 content accompanied by decreasing of C-2-C-4, heavy isotopic enrichment of C-1-C-4, and differential hydrogen isotopic fractionation of C-1 and C-2-C-4 relative to theoretical calculation, suggest C-2-C-4 were preferentially oxidized during TOH, and C-1 had been consumed in reaction. As TOH proceeded the C-13- and H-2-enrichment of C-1-C-4 was mainly caused by the Rayleigh fractionation. Involvement of formation water in the reaction intermediates of TOH is likely another factor causing the abnormal H-2-enrichment of C-1 and the reversals. This study demonstrates that in some circumstances the TOH reactions induced by high-valence metal oxides cause large differences in the hydrogen isotopic compositions of natural hydrocarbons, and the process can be identified via their molecular and hydrogen isotopic signatures.
英文关键词	Thermochemical hydrocarbon oxidation; High-valence Mn/Fe oxides; Deep clastic reservoirs; Hydrogen isotopes; Carbon isotopes; Junggar Basin
语种	英语
WOS研究方向	Geochemistry & Geophysics
WOS类目	Geochemistry & Geophysics
WOS记录号	WOS:000616149200005
来源期刊	CHEMICAL GEOLOGY
来源机构	中国科学院西北生态环境资源研究院
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/254755
作者单位	[Kang, Xun; Tan, Jingqiang] Cent South Univ, Sch Geosci & Info Phys, Key Lab Metallogen Predict Nonferrous Met & Geol, Minist Educ, Changsha 410083, Peoples R China; [Hu, Wenxuan; Wang, Xiaolin] Nanjing Univ, Sch Earth Sci & Engn, State Key Lab Mineral Deposits Res, Nanjing 210023, Jiangsu, Peoples R China; [Li, Zhongping] Chinese Acad Sci, Northwest Inst Ecoenvironm & Resources, Lanzhou 730000, Peoples R China; [Xiang, Baoli; Wang, Jian] PetroChina, Xinjiang Oilfield Co, Karamay 834000, Peoples R China
推荐引用方式 GB/T 7714	Kang, Xun,Hu, Wenxuan,Tan, Jingqiang,et al. Hydrogen isotopic responses to thermochemical oxidation of light hydrocarbon gases in deep clastic reservoirs of the Junggar Basin, China[J]. 中国科学院西北生态环境资源研究院,2021,563.
APA	Kang, Xun.,Hu, Wenxuan.,Tan, Jingqiang.,Li, Zhongping.,Xiang, Baoli.,...&Wang, Xiaolin.(2021).Hydrogen isotopic responses to thermochemical oxidation of light hydrocarbon gases in deep clastic reservoirs of the Junggar Basin, China.CHEMICAL GEOLOGY,563.
MLA	Kang, Xun,et al."Hydrogen isotopic responses to thermochemical oxidation of light hydrocarbon gases in deep clastic reservoirs of the Junggar Basin, China".CHEMICAL GEOLOGY 563(2021).