| Isotopic evidence of TSR origin for natural gas bearing high H_2S contents within the Feixianguan Formation of the northeastern Sichuan Basin, southwestern China |
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| 作者姓名： | ZHU Guangyou ZHANG Shuichang LIANG Yingbo DAI Jinxing & LI Jian Research Institute of Petroleum Exploration and Development PetroChina Beijing China |
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| 作者单位： | ZHU Guangyou，ZHANG Shuichang，LIANG Yingbo，DAI Jinxing & LI Jian Research Institute of Petroleum Exploration and Development，PetroChina，Beijing 100083，China |
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| 基金项目： | the G&G Research Institute of the Chinese Academy of Sciences nad the Laboratory of the E&P Institute of Petrochina，the project of "The resource distribution and development strategy of the gas fields with high H2S content in China"，PetroChina and the National Key Basic Research and Development Planning Project |
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| 摘 要： | Isotopic evidence of TSR origin for natural gas bearing high H2S contents 1961 As the hazardous component of natural gas, the ex-istence of H2S, due to its extremely strong toxicity and corrosivity, not only decreases the percentage of hy-drocarbon gas within natural gas and reduces its in-dustrial value, it also threatens each aspect of drilling and exploitation. It frequently causes serious safety accidents1] and leads to the E&P cost and risk of natural gas with higher H2S contents be…
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Isotopic evidence of TSR origin for natural gas bearing high H2S contents within the Feixianguan Formation of the northeastern Sichuan Basin, southwestern China |
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| ZHU Guangyou,ZHANG Shuichang,LIANG Yingbo,DAI Jinxing & LI Jian Research Institute of Petroleum Exploration and Development,PetroChina,Beijing ,China.Isotopic evidence of TSR origin for natural gas bearing high H_2S contents within the Feixianguan Formation of the northeastern Sichuan Basin, southwestern China[J].Science in China(Earth Sciences),2005,48(11). |
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| Authors: | ZHU Guangyou ZHANG Shuichang LIANG Yingbo DAI Jinxing LI Jian |
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| Institution: | Research Institute of Petroleum Exploration and Development, PetroChina, Beijing 100083, China |
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| Abstract: | The northeastern area of Sichuan Basin, southwestern China, is the area with the maximal reserve of natural gas containing higher hydrogen sulphide (H2S) that has been found among the petroliferous basins of China, with the proven and controlled gas reserve of more than 200 billion cubic meters. These gas pools, with higher H2S contents averaging 9%, some 17%, are mainly distributed on structural belts of Dukouhe, Tieshanpo, Luojiazhai, Puguang, etc., while the oolitic-shoal dolomite of the Triassic Feixianguan Fm. (T1f) is the reservoir. Although many scholars regard the plentiful accumulation of H2S within the deep carbonate reservoir as the result of Thermochemical Sulfate Reduction (TSR), however, the process of TSR as well as its residual geological and geochemical evidence is still not quite clear. Based on the carbon isotopic analysis of carbonate strata and secondary calcite, etc., together with the analysis of sulfur isotopes within H2S, sulphur, gypsum, iron pyrites, etc., as well as other aspects including the natural gas composition, carbon isotopes of hydrocarbons reservoir petrology, etc., it has been proved that the above natural gas is a product of TSR. The H2S, sulphur and calcite result from the participation of TSR reactions by hydrocarbon gas. During the process for hydrocarbons being consumed due to TSR, the carbons within the hydrocarbon gas participate in the reactions and finally are transferred into the secondary calcite, and become the carbon source of secondary calcite, consequently causing the carbon isotopes of the secondary calcite to be lower (-18.2‰). As for both the intermediate product of TSR, i.e. sulfur, and its final products, i.e. H2S and iron pyrites, their sulfur elements are all sourced from the sulfate within the Feixianguan Fm. During the fractional processes of sulfur isotopes, the bond energy leads to the 32S being released firstly, and the earlier it is released, the lower δ34S values for the generated sulphide (H2S) or sulfur will be. However, for the anhydrite that participates in reactions, the higher the reaction degree, the more 32S is released, while the less 32S remains and the more δ34S is increased. The testing results have proved the process of the dynamic fractionation of sulfur isotopes. |
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| Keywords: | hydrogen sulphide sulfate sulfur isotope carbon isotope thermochemical sulfate reduction northeastern Sichuan Basin |
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