Geochemical characteristics and origin of natural gas in the Dongping–Niudong areas, Qaidam Basin, China

Journal of Natural Gas Geoscience

Guojie Sui¹  Caixia Wang²  Shoukai Cui³  Jingru Wang⁴  Zhiqiang Liu⁴  Fei Zhou⁴  Yongshu Zhang⁴  Jun Zhu⁴  Guoyan Li⁴  Yi Zhang⁴ 

[1] Chengxin Services Company, Qinghai Oilfield Company, PetroChina, Dunhuang 736202, China;Faculty of Earth Resources, China University of Geosciences, Wuhan 430074, China;No. 2 Producing Plant, Qinghai Oilfield Company, PetroChina, Dunhuang 736202, China;Research Institute of Exploration and Development, Qinghai Oilfield Company, PetroChina, Dunhuang 736202, China;

关键词: Gas;    Component of gas;    Stable carbon isotope;    Coal-derived gas;    Qaidam Basin;   

DOI  :  10.1016/j.jnggs.2016.11.008

来源: DOAJ

【 摘 要 】

The geochemical characteristics, origin, and source of natural gas in the Dongping–Niudong areas are researched based on the information of components and the stable carbon isotopes of natural gas. The main component of hydrocarbon gas is methane, and C2+ possesses a relatively low content that ranges from 0.5% to 6.5%. The dryness coefficient of the Dongping area is more than 0.97, which categorizes as dry gas. The dryness coefficient of the Niudong area ranges from 90.3% to 98.1%, whilst having the characteristics of dry gas coexisting with wet gas. The δ13C1 dryness coefficient varies from −17.58‰ to −36.4‰, and δ13C2 is greater than −29‰. The gas of the Dongping 3 block has the characteristics of an abiogenic gas such as the reversed carbon isotope series. The combination of the relationship between the component of CO2 and δCCO213 and the background of development of hydrocarbon-generating sag, suggests that it is coal-derived gas. The RO and fluid inclusion studies show that the gas in Niudong area is mainly derived from Early Jurassic coal-measure source rocks of Kunteyi Sag, and there are two periods of hydrocarbon fillings. The first filling is mainly oil, and the second is mainly high mature gas; gas in Dongping area is mainly derived from Early Jurassic coal-measure source rocks of Pingdong–Yiliping Sag, and there are four periods of high-over mature gas fillings. The phenomenon of reversed carbon isotope series in Dongping area resulted from the multiple gas charging.

【 授权许可】

Unknown