Geochemistry and accumulation of carbon dioxide gases in China

Journal Article · Tue Oct 01 04:00:00 EDT 1996 · AAPG Bulletin

OSTI ID:405384

Dai, Jin-xing; Song, Yan; Dai, Chun-sen; Wang, Da-rui ^[1]

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1. Research Institute of Petroleum Exploration and Development, Beijing (China)

We propose the following identification indicators for CO{sub 2} of different origins based on data obtained from analyzing the molecular composition of 1198 gas samples, the CO{sub 2} carbon isotope values of 390 samples, and the helium isotope composition of 256 samples collected from wells of 16 oil- and gas-bearing basins and gas seepages in China, and reviewing literature on organic and inorganic CO{sub 2} throughout the world. CO{sub 2} is of organic origin if CO{sub 2} content <15% and {delta}{sup 13}C{sub CO2} <{minus}10{per_thousand}; CO{sub 2} is of inorganic origin if {delta}{sup 13}C{sub CO2} > {minus}8{per_thousand} or CO{sub 2} > 60%; and CO{sub 2} is of either organic or inorganic origin or a mixture of organic and inorganic origins if {minus}10{per_thousand} < {minus}8{per_thousand}. In China, the {delta}{sup 13}C{sub CO2} values of organic CO{sub 2} mainly range from {minus}10 to {minus}22%{per_thousand}. In tectonically stable oil- and gas-bearing basins where deep faults and magmatism are undeveloped, organic CO{sub 2} occurs almost exclusively. In tectonically active oil- and gas-bearing basins where active faults and magmatism are present or in areas of modern volcanic activity, the {delta}{sup 13}C{sub CO2} values of inorganic CO{sub 2} range from {minus}2 to {minus}8{per_thousand} and are distributed along faults. The inorganic CO{sub 2} with a {delta}{sup 13}C{sub CO2} value of 0 {plus_minus}3{per_thousand} is of metamorphic origin, and that with {delta}{sup 13}C{sub CO2} values of {minus}6{plus_minus}2{per_thousand} is mantle derived and of magmatic origin. In China, the {delta}{sup 13}C{sub CO2} values of inorganic CO{sub 2} gas pools range from {minus}3.41 to {minus}8.44{per_thousand} and the helium ratio (R:Ra) is >1, which indicates that these gases are typically derived form the mantle.

• OSTI ID: 405384
• Journal Information: AAPG Bulletin, Journal Name: AAPG Bulletin Journal Issue: 10 Vol. 80; ISSN 0149-1423; ISSN AABUD2
• Country of Publication: United States
• Language: English

Related Subjects

03 NATURAL GAS
54 ENVIRONMENTAL SCIENCES
ABUNDANCE
CARBON DIOXIDE
CHINA
GEOCHEMISTRY
GREENHOUSE GASES
NATURAL GAS
NATURAL GAS DEPOSITS
ORIGIN