Mixed carbonate-siliciclastic reservoir characterization and hydrocarbon accumulation process of the Ganchaigou area in the western Qaidam Basin, Tibet Plateau

Wu, Haifeng; Liu, Hui; Wang, Long; Gui, Lili; Cheng, Yang; Wang, Lixin

doi:10.1007/s13146-022-00769-2

Cited by 5 publications

(5 citation statements)

References 57 publications

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“…The Paleogene and Neogene source rocks in the western Qaidam Basin are dominated by lacustrine dark mudstone and calcareous mudstone with gypsum and salt beds (Huang, et al, 2018;Yi et al, 2017), which is oil-prone and generate low-mature to mature oil with minor gas production (Guo et al, 2020;Wu et al, 2022). However, the proved natural gas reserves are currently far from the estimated geological natural gas resources, indicating potential gas exploration prospect (Guo et al, 2017;Tian et al, 2018).…”

Section: Geological Settingmentioning

confidence: 99%

“…The structural pattern of the Yingxiongling Area varies signi cantly from west to east. It is characterized by a double-layer structure in vertical in the middle and the west, e.g., the upper layered salt rocks can work as a high-pressure crop rocks, and fractures and joints at subsalt reservoirs are conducive to oil and gas migration and accumulation, where CH 4 is mainly derived from crude-oil-associated gas (Ma et al, 2019;Wu et al, 2022;Xia et al., 2019). The structure pattern is relatively simple in the east with no salt rocks, where episodic charging occurred from deep to shallow, with natural gas as by-product of condensate (Ma et al, 2018a;Sun et al, 2013).…”

Section: Geological Settingmentioning

confidence: 99%

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Microbial Communities and Sulfur Isotopes of the Cenozoic Sulfurous Oil Reservoirs in the Southwestern Qaidam Basin, Western China

Jiao

Wang

et al. 2023

Preprint

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Sulfur-rich natural gas reservoirs have been discovered in the southwestern margin of the Qaidam Basin, marking a breakthrough in the Cenozoic natural gas exploration. 16S rRNA extraction and analysis were performed on crude oil samples from H2S-rich reservoirs at the Yuejin, Shizigou and Huatugou profiles to understand the sulfurous gas origination, which was also intergrated with carbon and hydrogen isotopes of alkane and sulfur isotopes of H2S collected from the Yingxiongling Area. Results show that microorganisms in crude oil can be classified into Proteobacteria, Planctomycetes, Firmicutes, Bacteroidetes, Haloanaerobe, etc., which can survive in hypersaline reservoirs. Methanogens and nitrate-reducing bacteria are popular in three profiles, while sulfate-reducing bacteria are abundant in Yuejin and Huatugou profiles, which contributed to methane and H2S in natural gas. The gas components and sulfur isotopes at the Yingxiongling Area show that the natural gas was mixed by coal-type gas and oil-type gas, which was primarily derived from thermal degradation, and natural gas from the Yuejin and Huatugou profiles also origniated from biodegradation. It agrees well with the tested microbial sequencing, i.e., H2S-rich natural gas from the Cenozoic reservoirs in the southwest margin of the Qaidam Basin was primarily thermal genesis, with microbial genesis of secondary importance.

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Section: Geological Settingmentioning

confidence: 99%

Section: Geological Settingmentioning

confidence: 99%

Microbial Communities and Sulfur Isotopes of the Cenozoic Sulfurous Oil Reservoirs in the Southwestern Qaidam Basin, Western China

Jiao

Wang

et al. 2023

Preprint

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“…The Paleogene and Neogene source rocks in the western Qaidam Basin are dominated by lacustrine dark mudstone and calcareous mudstone with gypsum and salt beds 37 , 60 , the salinized deposits mainly originated from hot-arid climate with high evaporation 36 , which is mainly oil-prone, and generates low-mature to mature oil with minor gas production 61 , 62 . However, the proved natural gas reserves are currently far from the estimated geological natural gas resources, indicating potential gas exploration prospect 30 , 63 .…”

Section: Geological Settingmentioning

confidence: 99%

“…The structural pattern of the Yingxiongling Area varies significantly from west to east. It is characterized by a double-layer structure in vertical in the middle and the west, i.e., the upper layered salt rocks can work as a high-pressure cap rocks, and fractures and joints at the subsalt reservoirs are conducive to oil and gas migration, where CH 4 is mainly derived from crude-oil-associated gas 62 , 66 , 67 . The eastern part of the Yingxiongling Area lacks salt caprocks (mainly halite) and possess a relatively simple structural pattern, with episodic charging of petroleum occurred from deep to shallow, in which natural gas is the by-product of condensate oil 56 , 68 .…”

Section: Geological Settingmentioning

confidence: 99%

Microbial communities and their roles in the Cenozoic sulfurous oil reservoirs in the Southwestern Qaidam Basin, Western China

Jiao

Wang³

et al. 2023

Sci Rep

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The latest discovery of sulfurous natural gas marked a breakthrough in the Cenozoic natural gas exploration in the southwestern margin of Qaidam Basin. The 16S rRNA analyses were performed on the crude oil samples from H2S-rich reservoirs in the Yuejin, Shizigou and Huatugou profiles, to understand the sulfurous gas origin, which was also integrated with carbon and hydrogen isotopes of alkane and sulfur isotopes of H2S collected from the Yingxiongling Area. Results show that the microorganisms in samples can survive in the hypersaline reservoirs, and can be classified into multiple phyla, including Proteobacteria, Planctomycetes, Firmicutes, Bacteroidetes, and Haloanaerobiaeota. Methanogens are abundant in all of the three profiles, while sulfate-reducing bacteria are abundant in Yuejin and Huatugou profiles, contributing to the methane and H2S components in the natural gas. The carbon, hydrogen and sulfur isotopes of sulfurous natural gas in the Yingxiongling Area show that the natural gas is a mixture of coal-type gas and oil-type gas, which was primarily derived from thermal degradation, and natural gas from the Yuejin and Huatugou profiles also originated from biodegradation. The isotopic analysis agrees well with the 16S rRNA results, i.e., H2S-rich natural gas from the Cenozoic reservoirs in the southwest margin of the Qaidam Basin was primarily of thermal genesis, with microbial genesis of secondary importance.

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“…Additionally, the Yingxiongling area of the Qaidam Basin exhibits globally distinctive giant saline lacustrine shale oil reservoirs within the Paleogene Lower Ganchaigou Formation (LGCG), indicating promising prospects for oil and gas exploration [17]. Currently, due to the significant discoveries and favorable exploration prospects of unconventional oil and gas in the LGCG, numerous scholars have focused on the characterization, identification, and evaluation of the mixed rock reservoirs in this area [20][21][22][23]. However, studies related to the subdivision of sequences in fine-grained sediments, and the paleoclimatic significance of this extensive and thick mixed rock succession, are still lacking and remain controversial.…”

Section: Introductionmentioning

confidence: 99%

High-Frequency Lacustrine Lithological and Geochemical Variations in the Eocene Qaidam Basin: Implications for Paleoenvironment Reconstruction

Wu,

Tan,

Liu

et al. 2024

Minerals

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Lacustrine sedimentary processes exhibit high sensitivity to paleoenvironmental changes, often manifesting as high-frequency sedimentary cycles that control the complex variations in sedimentary structure, mineral composition, and element distribution. However, the intricate co-variation mechanism among paleoclimate and paleowater properties at a high precision level (centimeter to meter scale) is still controversial. This study focuses on conducting a high-frequency cycle analysis of lacustrine mixed rocks from the Eocene Lower Ganchaigou Formation (LGCG) in the Qaidam Basin, employing petrology, mineralogy, organic geochemistry, and elemental geochemistry techniques. The lithological variation was characterized by the superposition of three lithofacies types from the bottom to the top with a single sequence: massive sandstone, laminated silty shale, and bedded calcareous dolostone. Geochemical data revealed cyclical variations in the paleoenvironment in the vertical profile, which conformed to the high-frequency lithofacies cycles. Based on the reconstruction of the lake level and paleowater properties, a synthesized paleoclimate–sedimentary model that comprised three consecutive periods within an individual sequence was established. From the bottom to the top of each cycle, the Eocene paleoenvironment varied from reduction and desalination to oxidation and salinization, which was controlled by a decline in the lake level resulting from a transformation of the paleoclimate from warm and humid to cold and arid. The variations in petrology and geochemistry observed in the Eocene Qaidam Basin play a crucial role in comprehending the sedimentary response to paleoenvironmental changes at high precision levels within lacustrine settings.

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Mixed carbonate-siliciclastic reservoir characterization and hydrocarbon accumulation process of the Ganchaigou area in the western Qaidam Basin, Tibet Plateau

Cited by 5 publications

References 57 publications

Microbial Communities and Sulfur Isotopes of the Cenozoic Sulfurous Oil Reservoirs in the Southwestern Qaidam Basin, Western China

Microbial Communities and Sulfur Isotopes of the Cenozoic Sulfurous Oil Reservoirs in the Southwestern Qaidam Basin, Western China

Microbial communities and their roles in the Cenozoic sulfurous oil reservoirs in the Southwestern Qaidam Basin, Western China

High-Frequency Lacustrine Lithological and Geochemical Variations in the Eocene Qaidam Basin: Implications for Paleoenvironment Reconstruction

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