A review of alkane gas geochemistry in the Xujiaweizi fault-depression, Songliao Basin

作者：Zeng Huasen^*; Li Jingkun; Huo Qiuli

来源：Marine and Petroleum Geology, 2013, 43: 284-296.

DOI：10.1016/j.marpetgeo.2013.01.009

• Songliao Basin
• Volcanic reservoir
• Carbon isotopic reversal
• Wet-gas cracking
• Abiogenic polymerization

A large suite (172) of gases from the Yingcheng Fm. in the Xujiaweizi fault-depression has been studied chemically and isotopically. The results show that they are mainly type-III kerogen/coal-type gas and have been generated and accumulated under the influence of hydrothermal fluids. Both measured and calculated vitrinite reflectance data show that they have been generated mainly at source maturity higher than 2.0%Ro. Many gases show carbon isotopic reversals (typically, delta C-13(1) > delta C-13(2) and delta C-13(2) > delta C-13(3)). The origin of carbon isotopic reversals is discussed in this paper and the results show that previous interpretations, including (a) mixing and (b) the occurrence of abiogenic gases, are incorrect. Based on iso-butane/n-butane data, wet-gas cracking may have occurred but it is not the main cause of carbon isotopic reversals here. We propose that a process of abiogenic polymerization of C2+ gases with methane is the main cause of the carbon isotopic reversals in this basin.

• 出版日期2013-5
• 单位大庆油田有限责任公司勘探开发研究院