caa a22 4500 445300868 CHVBK 20180317142557.0 cr unu---uuuuu 170323e20100501xx s 000 0 eng 10.1007/s11430-010-0046-7 doi (NATIONALLICENCE)springer-10.1007/s11430-010-0046-7 Origin of CO2 in natural gas from the Triassic Feixianguan Formation of Northeast Sichuan Basin [Elektronische Daten] [SiJing Huang, KeKe Huang, HongPeng Tong, LiHong Liu, Wei Sun, QianQian Zhong] The natural gas from the Triassic Feixianguan Formation of Northeast Sichuan Basin contains high H2S whereas relatively low CO2 concentrations and the CO2 display high δ 13C values (ranging from −5.81‰ to 3.3‰ (PDB)). This seems to contradict the conventional wisdom that TSR should be a primary source of CO2 in natural gas from the Feixianguan Formation. In contrast, many authigenic calcite samples from these sites display very low δ 13C values (ranging from −18.4‰ to −10.3‰ (PDB)). This suggests that the carbon from TSR source dominated the formation of calcite whereas the carbon from inorganic source came into CO2 in natural gas. In order to assess the origin of CO2 from these H2S-rich sites, we have calculated the relative contributions of organic and inorganic carbon sources to the CO2 and authigenic calcite. The organic carbon source possibly originated from TSR, whereas the inorganic one might be generated from marine carbonates dissolution. This calculation is based on the carbon isotopic compositions of CO2 and authigenic calcite as well as an isotopic mass balance. The results show that the contribution of organic carbon source to the CO2 is only 2%, whereas that to authigenic calcite is as high as 43% on average. Such results combined with thermodynamic evidence indicate that the isotopically light CO2 produced by TSR process may contribute to authigenic calcite precipitation during burial diagenesis. Distinguishable from Ordovician reservoir of Tarim Basin, Feixianguan reservoir of Northeast Sichuan Basin experienced rapid tectonic uplift due to Yanshanian movement after TSR occurred. Such tectonic event could induce temperature decrease and further promote carbonates dissolution. During these processes, secondary porosity has developed in Feixianguan carbonate reservoirs. Therefore, much attention should be paid to the structural highs in search of high quality carbonate reservoirs. Science China Press and Springer-Verlag Berlin Heidelberg, 2010 northeastern Sichuan nationallicence Feixianguan Formation nationallicence origin of CO2 nationallicence TSR nationallicence tectonic uplift nationallicence carbonates precipitation and dissolution nationallicence Huang SiJing State Key Lab of Oil and Gas Reservoir Geology and Exploitation, Institute of Sedimentary Geology, Chengdu University of Technology, 610059, Chengdu, China aut Huang KeKe State Key Lab of Oil and Gas Reservoir Geology and Exploitation, Institute of Sedimentary Geology, Chengdu University of Technology, 610059, Chengdu, China aut Tong HongPeng State Key Lab of Oil and Gas Reservoir Geology and Exploitation, Institute of Sedimentary Geology, Chengdu University of Technology, 610059, Chengdu, China aut Liu LiHong State Key Lab of Oil and Gas Reservoir Geology and Exploitation, Institute of Sedimentary Geology, Chengdu University of Technology, 610059, Chengdu, China aut Sun Wei State Key Lab of Oil and Gas Reservoir Geology and Exploitation, Institute of Sedimentary Geology, Chengdu University of Technology, 610059, Chengdu, China aut Zhong QianQian State Key Lab of Oil and Gas Reservoir Geology and Exploitation, Institute of Sedimentary Geology, Chengdu University of Technology, 610059, Chengdu, China aut Science China Earth Sciences SP Science China Press 53/5(2010-05-01), 642-648 1674-7313 53:5<642 2010 53 11430 https://doi.org/10.1007/s11430-010-0046-7 text/html Onlinezugriff via DOI 1 research-article jats NATIONALLICENCE 856 40 https://doi.org/10.1007/s11430-010-0046-7 text/html Onlinezugriff via DOI NATIONALLICENCE 700 1- Huang SiJing State Key Lab of Oil and Gas Reservoir Geology and Exploitation, Institute of Sedimentary Geology, Chengdu University of Technology, 610059, Chengdu, China aut NATIONALLICENCE 700 1- Huang KeKe State Key Lab of Oil and Gas Reservoir Geology and Exploitation, Institute of Sedimentary Geology, Chengdu University of Technology, 610059, Chengdu, China aut NATIONALLICENCE 700 1- Tong HongPeng State Key Lab of Oil and Gas Reservoir Geology and Exploitation, Institute of Sedimentary Geology, Chengdu University of Technology, 610059, Chengdu, China aut NATIONALLICENCE 700 1- Liu LiHong State Key Lab of Oil and Gas Reservoir Geology and Exploitation, Institute of Sedimentary Geology, Chengdu University of Technology, 610059, Chengdu, China aut NATIONALLICENCE 700 1- Sun Wei State Key Lab of Oil and Gas Reservoir Geology and Exploitation, Institute of Sedimentary Geology, Chengdu University of Technology, 610059, Chengdu, China aut NATIONALLICENCE 700 1- Zhong QianQian State Key Lab of Oil and Gas Reservoir Geology and Exploitation, Institute of Sedimentary Geology, Chengdu University of Technology, 610059, Chengdu, China aut NATIONALLICENCE 773 0- Science China Earth Sciences SP Science China Press 53/5(2010-05-01), 642-648 1674-7313 53:5<642 2010 53 11430 Metadata rights reserved Springer special CC-BY-NC licence nationallicence BK010053 XK010053 XK010000 NATIONALLICENCE NATIONALLICENCE NL-springer