Occurrence characteristics of shale oil in the second submember of Da'anzhai Member of Jurassic Ziliujing Formation, central Sichuan Basin

Although China has abundant lacustrine shale oil resources, their exploitation is challenging. Investigating the various occurrence states of shale oil in shale reservoirs provides value for the exploration and development of shale oil resources. With the shale in the second submember of Da'anz...

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Main Authors: Chenyu ZHANG, Ziyi LIU, Bin WANG, Shuaiqiang SHAN, Jianlin LU, Baohua WANG, Zongxin ZUO
Format: Article
Language:zho
Published: Editorial Office of Petroleum Geology and Experiment 2024-11-01
Series:Shiyou shiyan dizhi
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Online Access:https://www.sysydz.net/cn/article/doi/10.11781/sysydz2024061215
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author Chenyu ZHANG
Ziyi LIU
Bin WANG
Shuaiqiang SHAN
Jianlin LU
Baohua WANG
Zongxin ZUO
author_facet Chenyu ZHANG
Ziyi LIU
Bin WANG
Shuaiqiang SHAN
Jianlin LU
Baohua WANG
Zongxin ZUO
author_sort Chenyu ZHANG
collection DOAJ
description Although China has abundant lacustrine shale oil resources, their exploitation is challenging. Investigating the various occurrence states of shale oil in shale reservoirs provides value for the exploration and development of shale oil resources. With the shale in the second submember of Da'anzhai Member of Jurassic Ziliujing Formation of the central Sichuan Basin (the Da2 submember) as the research object, the study reveals the occurrence modes of shale oil under different states in various medium pores, through the implementation of the multi-temperature pyrolysis experiment, the observation of pore development characteristics under the scanning electron microscope and the analysis of the pore size distribution before and after oil washing. In the Da2 submember, the shale oil is mainly in the free state (0.42 to 10.88 mg/g), followed by the adsorption state (0.30 to 1.95 mg/g), as revealed by thermal simulation recovery. The reservoir space of shale includes organic pores (pore size: 2 to 600 nm), pyrite intergranular pores (pore size: 10 to 700 nm), shell pores (pore size: 20 to 1 000 nm), quartz/feldspar intergranular pores (pore size: 4 to 500 nm) and clay mineral intergranular pores (pore size: 4 to 500 nm). After oil washing, the results of nitrogen adsorption and high pressure mercury injection demonstrated a significant increase in pores with sizes of 2 to 30 nm and 60 to 1 000 nm, where most of shale oil is stored. Meanwhile, it was demonstrated that the shale oil in the Da2 submember mainly occurs in organic matter and pyrite by establishing a heat map of the relationship between the occurrence state of shale oil and the medium in the rock. Lastly, by fitting the content of shale oil in different occurrence states with the oil volume obtained before and after oil washing, the pore size range for shale oil accumulation in the study area was determined. The free state of shale oil in the Da2 submember primarily accumulates in pores of organic matter and pyrite with pore size of 60 to 700 nm, and the adsorbed state of shale oil mainly accumulates in the organic matter pores with pore size of 2 to 6 nm. In conclusion, this study presents a thorough examination of the occurrence characteristics of shale oil in Da2 submember, and it will support shale oil exploitation efforts in the area.
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spelling doaj-art-d4d7a6f2e19f4559afddd4f264f146352025-08-20T02:49:26ZzhoEditorial Office of Petroleum Geology and ExperimentShiyou shiyan dizhi1001-61122024-11-014661215122510.11781/sysydz2024061215sysydz-46-6-1215Occurrence characteristics of shale oil in the second submember of Da'anzhai Member of Jurassic Ziliujing Formation, central Sichuan BasinChenyu ZHANG0Ziyi LIU1Bin WANG2Shuaiqiang SHAN3Jianlin LU4Baohua WANG5Zongxin ZUO6Wuxi Research Institute of Petroleum Geology, SINOPEC, Wuxi, Jiangsu 214126, ChinaWuxi Research Institute of Petroleum Geology, SINOPEC, Wuxi, Jiangsu 214126, ChinaWuxi Research Institute of Petroleum Geology, SINOPEC, Wuxi, Jiangsu 214126, ChinaWuxi Research Institute of Petroleum Geology, SINOPEC, Wuxi, Jiangsu 214126, ChinaWuxi Research Institute of Petroleum Geology, SINOPEC, Wuxi, Jiangsu 214126, ChinaWuxi Research Institute of Petroleum Geology, SINOPEC, Wuxi, Jiangsu 214126, ChinaWuxi Research Institute of Petroleum Geology, SINOPEC, Wuxi, Jiangsu 214126, ChinaAlthough China has abundant lacustrine shale oil resources, their exploitation is challenging. Investigating the various occurrence states of shale oil in shale reservoirs provides value for the exploration and development of shale oil resources. With the shale in the second submember of Da'anzhai Member of Jurassic Ziliujing Formation of the central Sichuan Basin (the Da2 submember) as the research object, the study reveals the occurrence modes of shale oil under different states in various medium pores, through the implementation of the multi-temperature pyrolysis experiment, the observation of pore development characteristics under the scanning electron microscope and the analysis of the pore size distribution before and after oil washing. In the Da2 submember, the shale oil is mainly in the free state (0.42 to 10.88 mg/g), followed by the adsorption state (0.30 to 1.95 mg/g), as revealed by thermal simulation recovery. The reservoir space of shale includes organic pores (pore size: 2 to 600 nm), pyrite intergranular pores (pore size: 10 to 700 nm), shell pores (pore size: 20 to 1 000 nm), quartz/feldspar intergranular pores (pore size: 4 to 500 nm) and clay mineral intergranular pores (pore size: 4 to 500 nm). After oil washing, the results of nitrogen adsorption and high pressure mercury injection demonstrated a significant increase in pores with sizes of 2 to 30 nm and 60 to 1 000 nm, where most of shale oil is stored. Meanwhile, it was demonstrated that the shale oil in the Da2 submember mainly occurs in organic matter and pyrite by establishing a heat map of the relationship between the occurrence state of shale oil and the medium in the rock. Lastly, by fitting the content of shale oil in different occurrence states with the oil volume obtained before and after oil washing, the pore size range for shale oil accumulation in the study area was determined. The free state of shale oil in the Da2 submember primarily accumulates in pores of organic matter and pyrite with pore size of 60 to 700 nm, and the adsorbed state of shale oil mainly accumulates in the organic matter pores with pore size of 2 to 6 nm. In conclusion, this study presents a thorough examination of the occurrence characteristics of shale oil in Da2 submember, and it will support shale oil exploitation efforts in the area.https://www.sysydz.net/cn/article/doi/10.11781/sysydz2024061215shale oiloccurrence stateoccurrence spaceoccurrence modesecond submember of da'anzhai memberjurassicsichuan basin
spellingShingle Chenyu ZHANG
Ziyi LIU
Bin WANG
Shuaiqiang SHAN
Jianlin LU
Baohua WANG
Zongxin ZUO
Occurrence characteristics of shale oil in the second submember of Da'anzhai Member of Jurassic Ziliujing Formation, central Sichuan Basin
Shiyou shiyan dizhi
shale oil
occurrence state
occurrence space
occurrence mode
second submember of da'anzhai member
jurassic
sichuan basin
title Occurrence characteristics of shale oil in the second submember of Da'anzhai Member of Jurassic Ziliujing Formation, central Sichuan Basin
title_full Occurrence characteristics of shale oil in the second submember of Da'anzhai Member of Jurassic Ziliujing Formation, central Sichuan Basin
title_fullStr Occurrence characteristics of shale oil in the second submember of Da'anzhai Member of Jurassic Ziliujing Formation, central Sichuan Basin
title_full_unstemmed Occurrence characteristics of shale oil in the second submember of Da'anzhai Member of Jurassic Ziliujing Formation, central Sichuan Basin
title_short Occurrence characteristics of shale oil in the second submember of Da'anzhai Member of Jurassic Ziliujing Formation, central Sichuan Basin
title_sort occurrence characteristics of shale oil in the second submember of da anzhai member of jurassic ziliujing formation central sichuan basin
topic shale oil
occurrence state
occurrence space
occurrence mode
second submember of da'anzhai member
jurassic
sichuan basin
url https://www.sysydz.net/cn/article/doi/10.11781/sysydz2024061215
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