Geochemistry on mantle-derived volatiles in natural gases from eastern China oil/gas provinces (I)
Commercial accumulation of mantle-derived helium in the sedimentary shell is discussed. Generally speaking, a commercial helium pool is formed by accumulated4He that comes from uranium and thorium via α-decay; therefore, it has a very low3He/4He value in the magnitude of 10-8. The helium concentration in some gas wells of eastern China oil/gas provinces is about or over 0.05% —0. 1%, consequently forming commercial helium wells (pools), such as the Wangjinta Gas Pool in Songliao Basin, Huangqiao Gas Pool in North Jiangsu Basin and some gas wells in Sanshui Basin. Studies have proved that when the3He/4He value of a helium gas pool is about 3.7 × 10-6 -7.2×10-6 namely mantle-derived helium in its total helium concentration accounts for 33.5%—65.4%, it is a crust-mantle dual-source or dominantly mantle-derived helium gas pool, which is a novel helium resource and its formation is mainly related to the distribution of megafractures.
Keywordsmantle-derived helium mantle volatile at present helium isotopic composition
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- 2.Craig, H., Lupton, J. E., Helium isotope variations,Trans Am Geophy Union, 1978, 58: 1194Google Scholar
- 5.Ozima, M., Podosek, F. A.,Noble Gas Geochemistry, Cambridge: Cambridge Univ Press, 1983Google Scholar
- 6.Xu Yongchang, Shen Ping, Tao Mingxinet al., A commercial accumulation of mantle-derived helium and the Tanlu megafracture zone,Chinese Science Bulletin, 1990, 35(12): 932Google Scholar
- 7.Qiu Songyu, Zhong Shiyou, Geological chararteristics of the Wanjinta CO2 gasfield in the southern Songliao Basin and its genesis,Oil & Gas Geology. 1985, 6(4) 434.Google Scholar
- 8.Tang Zhongyu, An approach to petrochemical characteristics of volcanism and volcanic rocks in the Sanshui basin,Marine Geology, 1987, (3): 50Google Scholar
- 10.Sakata, S., Takahashi, M., Hoshino, K., Geochemical study on genesis of natural gases accumulated in deep valcaniclastic rocks,Journal of the Japanese Association for Petroleum Technology, 1986, 51(3): 32Google Scholar