Recherche pétrolière et gazière

Abstrait

The Geochemical Properties and Provenance of Ordovician Ultra-deep Natural Gas

Kevin M Van Geem

Ultra-deep Ordovician period in Shuntuoguole space, Tarim Basin, NW China, has advanced oil & gas phases, during which light-weight oil, oil, atmospheric phenomenon and dry gas phases coexistent. The study compares the geochemical characteristics and origin of Ordovician period ultra-deep gas within the North Shuntuoguole (SB) space to it of gas within the Shuntuo (ST), South Shuntuoguole (SN), Gulong (GL), and Gucheng (GC) areas mistreatment gas composition, carbon atom and chemical element atom information and light-weight organic compound information. The Ordovician period ultra-deep gas within the SB space is wet gas, with waterlessness indexes starting from 0.52 to 0.88 and negligible H2S content. The carbon isotopes of gas area unit comparatively low, with δ13C1 and δ13C2 values starting from -49.6‰ to -44.7‰ and-39.3‰ to -32.7‰, severally. All the gas shows positive carbon and chemical element atom series. The n-alkane and iso-alkane dominate the C5–C7 light-weight organic compound, with the methylcyclohexane index of sunshine organic compound not up to thirty fifth. All of the Ordovician period gas within the Shuntuogule space is oil-type gas. The Ordovician period gas within the SB space is dominated by kerogen cracking gas, with a little fraction of wet gas from the first stages of oil cracking, whereas, all of the gas within the ST, SN, GL and GHz areas comes from oil cracking. The Cambrian supply rocks diode on to each styles of cracking gases. The distribution of 2 styles of cracking gas within the Shuntuogule space is related to with the utmost paleogeothermal temperature and (or) gift temperature of the Ordovician period.