Thermochemical sulphate reduction and the generation of hydrogen sulphide and thiols (mercaptans) in Triassic carbonate reservoirs from the Sichuan Basin, China
Thermochemical sulphate reduction and the generation of hydrogen sulphide and thiols (mercaptans) in Triassic carbonate reservoirs from the Sichuan Basin, China
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DOI：
10.1016/s0009-2541(03)00209-2
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发表时间：
2003-12-15
期刊：
影响因子：
3.9
通讯作者：
Yang, CC
中科院分区：
文献类型：
--
作者：
Cai, CF;Worden, RH;Yang, CC
中国四川盆地是一个含硫油气大省。为了评估H2S和其他硫化物的来源以及石油蚀变的原因，收集了来自侏罗纪、三叠系、二叠纪和上元古界（震旦系）储层的主要气相石油样品的H2S、噻吩和硫醇浓度和气体稳定同位素（δ（34）S和δ（13）C）数据。H2S浓度最高（高达32%）出现在卧龙河油田下三叠统富安山岩碳酸盐岩储层中，那里的温度已达到>130 ℃。卧龙河三叠系储层中H2S的δ（34）S值在+22 ~+31ppm之间，与华南三叠系碳酸盐型硫酸盐的δ（34）S值接近。所有证据表明，H2S是由热化学硫酸盐还原（TSR）局部三叠系储层内产生的。在三叠系卧龙河油田，甲烷和乙烷似乎都参与了热化学硫酸盐还原，因为随着TSR的进行，它们的δ（13）C值变得不那么负。在三叠系卧龙河气田，硫醇浓度与H2S呈正相关，表明硫醇的产生与TSR有关。相比之下，噻吩浓度升高仅在侏罗纪储层中发现，与贫硫源岩生成的液相石油有关。这可能表明噻吩化合物不是来自源岩或裂解石油。相反，它们可能是由储层中局部浓度的H2S和液态范围的石油化合物之间的反应产生的。然而，在盆地中，噻吩浓度随镜质组反射率的增加而降低，这表明源成熟度（而不是源类型）也可能是噻吩浓度的主要控制因素。(C)2003 Elsevier B. V.保留所有权利。
The Sichuan Basin in China is a sour petroleum province. In order to assess the origin of H2S and other sulphur compounds as well as the cause of petroleum alteration, data on H2S, thiophene and thiol concentrations and gas stable isotopes (delta(34)S and delta(13)C) have been collected for predominantly gas phase petroleum samples from Jurassic, Triassic, Permian and Upper Proterozoic (Sinian) reservoirs. The highest H2S concentrations (up to 32%) are found in Lower Triassic, anhydrite-rich carbonate reservoirs in the Wolonghe Field where the temperature has reached >130 degreesC. delta(34)S values of the H2S in the Wolonghe Triassic reservoirs range from +22 to +31 parts per thousand and are close to those of Triassic evaporitic sulphate from South China. All the evidence suggests that the H2S was generated by thermochemical sulphate reduction (TSR) locally within Triassic reservoirs. In the Triassic Wolonghe Field, both methane and ethane seem to be involved in thermochemical sulphate reduction since their delta(13)C values become less negative as TSR proceeds. Thiol concentrations correlate positively with H2S in the Triassic Wolonghe gas field, suggesting that thiol production is associated with TSR. In contrast, elevated thiophene concentrations are only found in Jurassic reservoirs in association with liquid phase petroleum generated from sulphur-poor source rocks. This may suggest that thiophene compounds have not come from a source rock or cracked petroleum. Rather they may have been generated by reaction between localized concentrations of H2S and liquid range petroleum compounds in the reservoir. However, in the basin, thiophene concentrations decrease with increasing vitrinite reflectance suggesting that source maturity (rather than source type) may also be a major control on thiophene concentration. (C) 2003 Elsevier B.V. All rights reserved.