The effect of thermochemical sulfate reduction on formation and isomerization of thiadiamondoids and diamondoids in the Lower Paleozoic petroleum pools of the Tarim Basin, NW China
The effect of thermochemical sulfate reduction on formation and isomerization of thiadiamondoids and diamondoids in the Lower Paleozoic petroleum pools of the Tarim Basin, NW China
复制标题
热化学硫酸盐还原对塔里木盆地下古生界含硫金刚石和金刚石类化合物形成和异构化的影响
DOI：
10.1016/j.orggeochem.2016.08.006
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发表时间：
2016-11-01
影响因子：
3
通讯作者：
Li, Hongxia
中科院分区：
文献类型：
--
作者：
Cai, Chunfang;Xiao, Qilin;Li, Hongxia
以塔里木盆地寒武系和奥陶系深埋碳酸盐岩储层原油和凝析油为研究对象，研究了热化学蚀变（TCA）和热化学硫酸盐还原（TSR）对原油和凝析油中噻二烃类和金刚烃类异构体形成和分布的影响。在所有分析的油中检测到具有1-3笼的金刚烷和噻二金刚烷。总噻二唑烃浓度反映了TSR的程度。类金刚石浓度和大多数类金刚石基成熟度代理和源岩岩性代理随TSR程度的增加而增加，表明它们在更大程度上受TSR过程（或与H2S反应）的控制。TSR可将烃氧化成含氧物质，并最终氧化成CO2和新生成的浓缩金刚烷和有机硫化合物。最广泛的TSR-改变的C11 C缩合物含有3.2wt%的总二苯并噻吩、0.4wt%的噻二烃类和5.9wt%的金刚烃类以及高级聚金刚烷，包括与聚噻二烃类结合的四金刚烷和五金刚烷，所述聚噻二烃类包括二硫杂金刚烷、三硫杂金刚烷和四硫杂金刚烷。这些聚噻二烃类化合物仅在本研究和北美样品中从严重TSR蚀变的石油中检测到，并且可能来自TSR高级阶段期间高温和高度还原条件下烃类化合物（包括金刚烃类化合物）的硫化。聚金刚烷可能是由低笼金刚烷的烷基化和随后的同系化或自由基反应产生的。该研究表明，TSR可能导致了thiadiamondoids和diamondoids的生成和异构化，因此基于diamondoids的成熟度和岩性指标不能用于反映TSR活动区的成熟度和岩性，而多thiadiamondoids的出现可以用来指示严重的TSR蚀变。(C)2016爱思唯尔有限公司版权所有。
We attempted to differentiate the effects of thermal chemical alteration (TCA) from thermochemical sulfate reduction (TSR) on formation and isomeric distribution of thiadiamondoids and diamondoids in oils and condensate from deeply buried Cambrian and Ordovician carbonate reservoirs in the Tarim Basin, China. Diamondoids and thiadiamondoids with 1-3 cages were detected in all the oils analyzed. Total thiadiamondoid concentrations reflect extent of TSR. Diamondoid concentrations and most of the diamondoid-based maturity proxies and the source rock lithology proxy increase with increasing extent of TSR, indicating that they are controlled by the extent of the TSR process (or reaction with H2S) to a greater degree than by TCA. TSR may have oxidized hydrocarbons to oxygenated species and finally to CO2 and newly generated and concentrated diamondoids and organic sulfur compounds. The most extensive TSR-altered ZS1C condensate contains 3.2 wt% total dibenzothiophenes, 0.4 wt% thiadiamondoids and 5.9 wt% diamondoids together with higher polymantanes including tetramantanes and pentamantanes in association with polythiadiamondoids, including dithiaadamantanes, trithiaadamantanes and tetrathiaadamantanes. These polythiadiamondoids have been detected only from heavily TSR-altered petroleum in this study and North American samples and may be derived from the sulfurization of hydrocarbons, including diamondoids, under high temperature and highly reducing conditions during advanced stages of TSR. The polymantanes may have been generated from alkylation of lower-cage diamondoids and subsequent homologation, or from free radical reactions. This study indicates that TSR may have led to the generation and isomerization of thiadiamondoids and diamondoids, and thus diamondoid-based maturity and lithology proxies cannot be used to reflect maturity and lithology in the TSR active areas, and that the occurrence of polythiadiamondoids can be used to indicate heavy TSR alteration. (C) 2016 Elsevier Ltd. All rights reserved.