Xiaoxiao Zhou, Xiaojun Li, Xu Song, Yuzhi Li, Xuejun Wang, Ke Han, Haiqing Yan
{"title":"中国东北渤海湾盆地东营凹陷深埋砂岩储层中始新世石油的地球化学分析","authors":"Xiaoxiao Zhou, Xiaojun Li, Xu Song, Yuzhi Li, Xuejun Wang, Ke Han, Haiqing Yan","doi":"10.1111/jpg.12872","DOIUrl":null,"url":null,"abstract":"<p>We report the results of organic geochemical analyses of 19 crude oil samples from reservoir sandstones in the 4th Member of the Eocene Shahejie Formation from wells in the Minfeng Sag, Dongying Depression, Bohai Bay Basin (NE China). In addition, 42 Shahejie Formation core samples of dark-coloured mudstones, including 28 extracts, were analysed. Geochemical data included Rock-Eval measurements, gas chromatography, GC-MS and diamondoid analyses.</p><p>Maceral analyses showed that mudstones in the 4th Member of the Shahejie Formation (“Es<sub>4</sub>”) contain Types I and II<sub>1</sub> kerogen. The member can be divided into upper (Es<sub>4</sub>s) and lower (Es<sub>4</sub>x) intervals. Oil-prone Es<sub>4</sub>s rock samples have good to excellent hydrocarbon-generating potential based on calculated initial TOC values; Rock-Eval T<sub>max</sub> values indicate that they are sufficiently mature for hydrocarbon generation. Analytical results suggest that both Es<sub>4</sub>s and Es<sub>4</sub>x mudrocks are potential source rocks for oils produced at fields in the Minfeng Sag.</p><p>Analysed crude oils from the Minfeng Sag were classified into three genetic groups. Group I oils are mature to highly mature and have undergone a moderate degree of thermal cracking. They are characterized by a low <i>β</i>-carotane/nC<sub>25</sub> ratio and C<sub>30</sub> 4-methylsterane index (4MI); high values of oleanane index (oleanane /C<sub>30</sub>-hopane), C<sub>27</sub> diasterane/C<sub>27</sub> regular sterane (C<sub>27</sub>Dia/C<sub>27</sub>), regular sterane/17<i>α</i> hopane and gammacerane/C<sub>30</sub> hopane (G/H); and medium pristane/phytane ratios (Pr/Ph). This suggests that Group I oils are mostly derived from source rocks in the upper part of the Es<sub>4</sub>x unit which are interbedded with evaporites. Group II oils are mature and have high 4MI and Pr/Ph ratios, low oleanane index, regular sterane/17<i>α</i> hopane and C<sub>27</sub>Dia/C<sub>27</sub> ratios, and medium<i>β</i>-carotane/nC<sub>25</sub> and G/H. These features are similar to those of Es<sub>4</sub>s source rocks, indicating their genetic correlation. Group III oils show the lowest maturity and high<i>β</i>-carotane/nC<sub>25</sub> and regular sterane/17<i>α</i> hopane, and low oleanane index, Pr/Ph and 4MI. Previously-published data indicates that oils similar to those in Group III were mainly sourced by Es<sub>4</sub>s mudstones.</p>","PeriodicalId":16748,"journal":{"name":"Journal of Petroleum Geology","volume":null,"pages":null},"PeriodicalIF":1.8000,"publicationDate":"2024-09-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":"{\"title\":\"GEOCHEMICAL ANALYSES OF EOCENE OILS IN DEEPLY BURIED SANDSTONE RESERVOIRS IN THE DONGYING DEPRESSION, BOHAI BAY BASIN, NE CHINA\",\"authors\":\"Xiaoxiao Zhou, Xiaojun Li, Xu Song, Yuzhi Li, Xuejun Wang, Ke Han, Haiqing Yan\",\"doi\":\"10.1111/jpg.12872\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<p>We report the results of organic geochemical analyses of 19 crude oil samples from reservoir sandstones in the 4th Member of the Eocene Shahejie Formation from wells in the Minfeng Sag, Dongying Depression, Bohai Bay Basin (NE China). In addition, 42 Shahejie Formation core samples of dark-coloured mudstones, including 28 extracts, were analysed. Geochemical data included Rock-Eval measurements, gas chromatography, GC-MS and diamondoid analyses.</p><p>Maceral analyses showed that mudstones in the 4th Member of the Shahejie Formation (“Es<sub>4</sub>”) contain Types I and II<sub>1</sub> kerogen. The member can be divided into upper (Es<sub>4</sub>s) and lower (Es<sub>4</sub>x) intervals. Oil-prone Es<sub>4</sub>s rock samples have good to excellent hydrocarbon-generating potential based on calculated initial TOC values; Rock-Eval T<sub>max</sub> values indicate that they are sufficiently mature for hydrocarbon generation. Analytical results suggest that both Es<sub>4</sub>s and Es<sub>4</sub>x mudrocks are potential source rocks for oils produced at fields in the Minfeng Sag.</p><p>Analysed crude oils from the Minfeng Sag were classified into three genetic groups. Group I oils are mature to highly mature and have undergone a moderate degree of thermal cracking. They are characterized by a low <i>β</i>-carotane/nC<sub>25</sub> ratio and C<sub>30</sub> 4-methylsterane index (4MI); high values of oleanane index (oleanane /C<sub>30</sub>-hopane), C<sub>27</sub> diasterane/C<sub>27</sub> regular sterane (C<sub>27</sub>Dia/C<sub>27</sub>), regular sterane/17<i>α</i> hopane and gammacerane/C<sub>30</sub> hopane (G/H); and medium pristane/phytane ratios (Pr/Ph). This suggests that Group I oils are mostly derived from source rocks in the upper part of the Es<sub>4</sub>x unit which are interbedded with evaporites. Group II oils are mature and have high 4MI and Pr/Ph ratios, low oleanane index, regular sterane/17<i>α</i> hopane and C<sub>27</sub>Dia/C<sub>27</sub> ratios, and medium<i>β</i>-carotane/nC<sub>25</sub> and G/H. These features are similar to those of Es<sub>4</sub>s source rocks, indicating their genetic correlation. Group III oils show the lowest maturity and high<i>β</i>-carotane/nC<sub>25</sub> and regular sterane/17<i>α</i> hopane, and low oleanane index, Pr/Ph and 4MI. Previously-published data indicates that oils similar to those in Group III were mainly sourced by Es<sub>4</sub>s mudstones.</p>\",\"PeriodicalId\":16748,\"journal\":{\"name\":\"Journal of Petroleum Geology\",\"volume\":null,\"pages\":null},\"PeriodicalIF\":1.8000,\"publicationDate\":\"2024-09-23\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Journal of Petroleum Geology\",\"FirstCategoryId\":\"89\",\"ListUrlMain\":\"https://onlinelibrary.wiley.com/doi/10.1111/jpg.12872\",\"RegionNum\":4,\"RegionCategory\":\"地球科学\",\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"Q3\",\"JCRName\":\"GEOSCIENCES, MULTIDISCIPLINARY\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Journal of Petroleum Geology","FirstCategoryId":"89","ListUrlMain":"https://onlinelibrary.wiley.com/doi/10.1111/jpg.12872","RegionNum":4,"RegionCategory":"地球科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"Q3","JCRName":"GEOSCIENCES, MULTIDISCIPLINARY","Score":null,"Total":0}
GEOCHEMICAL ANALYSES OF EOCENE OILS IN DEEPLY BURIED SANDSTONE RESERVOIRS IN THE DONGYING DEPRESSION, BOHAI BAY BASIN, NE CHINA
We report the results of organic geochemical analyses of 19 crude oil samples from reservoir sandstones in the 4th Member of the Eocene Shahejie Formation from wells in the Minfeng Sag, Dongying Depression, Bohai Bay Basin (NE China). In addition, 42 Shahejie Formation core samples of dark-coloured mudstones, including 28 extracts, were analysed. Geochemical data included Rock-Eval measurements, gas chromatography, GC-MS and diamondoid analyses.
Maceral analyses showed that mudstones in the 4th Member of the Shahejie Formation (“Es4”) contain Types I and II1 kerogen. The member can be divided into upper (Es4s) and lower (Es4x) intervals. Oil-prone Es4s rock samples have good to excellent hydrocarbon-generating potential based on calculated initial TOC values; Rock-Eval Tmax values indicate that they are sufficiently mature for hydrocarbon generation. Analytical results suggest that both Es4s and Es4x mudrocks are potential source rocks for oils produced at fields in the Minfeng Sag.
Analysed crude oils from the Minfeng Sag were classified into three genetic groups. Group I oils are mature to highly mature and have undergone a moderate degree of thermal cracking. They are characterized by a low β-carotane/nC25 ratio and C30 4-methylsterane index (4MI); high values of oleanane index (oleanane /C30-hopane), C27 diasterane/C27 regular sterane (C27Dia/C27), regular sterane/17α hopane and gammacerane/C30 hopane (G/H); and medium pristane/phytane ratios (Pr/Ph). This suggests that Group I oils are mostly derived from source rocks in the upper part of the Es4x unit which are interbedded with evaporites. Group II oils are mature and have high 4MI and Pr/Ph ratios, low oleanane index, regular sterane/17α hopane and C27Dia/C27 ratios, and mediumβ-carotane/nC25 and G/H. These features are similar to those of Es4s source rocks, indicating their genetic correlation. Group III oils show the lowest maturity and highβ-carotane/nC25 and regular sterane/17α hopane, and low oleanane index, Pr/Ph and 4MI. Previously-published data indicates that oils similar to those in Group III were mainly sourced by Es4s mudstones.
期刊介绍：
Journal of Petroleum Geology is a quarterly journal devoted to the geology of oil and natural gas. Editorial preference is given to original papers on oilfield regions of the world outside North America and on topics of general application in petroleum exploration and development operations, including geochemical and geophysical studies, basin modelling and reservoir evaluation.
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