This study is focused on geothermal heat flow and the origin of non-hydrocarbons in natural gases in terms of the isotope geochemical characteristics of Ar,He,CO2 and N2 in natural gases from the Sanshui Basin,Guangdo...This study is focused on geothermal heat flow and the origin of non-hydrocarbons in natural gases in terms of the isotope geochemical characteristics of Ar,He,CO2 and N2 in natural gases from the Sanshui Basin,Guangdong Province,China,^3He/^4He,ratios are of from the Sanshui Basin,Guangdong Province,China,^3He/^4He ratios are of (1.60-6.39)×10^-6,and ^40Ar/^36Ar ratios of 450841.The carbon isotopic composition (δ^13 C PDB)of carbon dioxide ranges from -20‰to -2‰,δ^15N (air) ratios have a wider range of -57‰-+95‰.The isotope geochemical characteristics of non-hydrocarbons indicate that He,Ar and N2 in the gas reservoirs enriched in non-hydrocarbons were derived largely from the upper mantle.Non-hydrocarbons in gaseous hydrocarbon reservoirs consist mainly of crustal radiogenic ^4He and ^40Ar and some mantle-derived He and Ar, as well as of ^13C-depleted carbon dioxide and nitrogen generated as a result of thermal decomposition of organic matter in strata.Carbon dioxide enriched in ^13C was derived largely from carbonate rocks and partially from the lower crust and upper mantle.Based on the relationship between geothermal heat flor(A)and ^3He/^4He ration in natural gases,the Q values for the area studied have been calculated.Similar Q values are reported from the upper mantle uplift area(77mWm^-2)in Huabei and the Tancheng Lujiang Rift Zone (88mWm^-2).More than 60 percent of geothermal heat flow in the Sanshui Basin may haee been derived from the upper mantle.展开更多
基金The project is financially supported by the National Natural Science Foundation of China.
文摘This study is focused on geothermal heat flow and the origin of non-hydrocarbons in natural gases in terms of the isotope geochemical characteristics of Ar,He,CO2 and N2 in natural gases from the Sanshui Basin,Guangdong Province,China,^3He/^4He,ratios are of from the Sanshui Basin,Guangdong Province,China,^3He/^4He ratios are of (1.60-6.39)×10^-6,and ^40Ar/^36Ar ratios of 450841.The carbon isotopic composition (δ^13 C PDB)of carbon dioxide ranges from -20‰to -2‰,δ^15N (air) ratios have a wider range of -57‰-+95‰.The isotope geochemical characteristics of non-hydrocarbons indicate that He,Ar and N2 in the gas reservoirs enriched in non-hydrocarbons were derived largely from the upper mantle.Non-hydrocarbons in gaseous hydrocarbon reservoirs consist mainly of crustal radiogenic ^4He and ^40Ar and some mantle-derived He and Ar, as well as of ^13C-depleted carbon dioxide and nitrogen generated as a result of thermal decomposition of organic matter in strata.Carbon dioxide enriched in ^13C was derived largely from carbonate rocks and partially from the lower crust and upper mantle.Based on the relationship between geothermal heat flor(A)and ^3He/^4He ration in natural gases,the Q values for the area studied have been calculated.Similar Q values are reported from the upper mantle uplift area(77mWm^-2)in Huabei and the Tancheng Lujiang Rift Zone (88mWm^-2).More than 60 percent of geothermal heat flow in the Sanshui Basin may haee been derived from the upper mantle.
