Reservoir space type and storage capacity of Oligocene lacustrine carbonate in the Yingxi area of western Qaidam Basin, China

Xia, Qingsong; Huang, Chenggang; Cui, Jun; Li, Yafeng

doi:10.1007/s13146-018-0476-4

Cited by 6 publications

(4 citation statements)

References 15 publications

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“…According to the results of earlier researchers [11], in this area, the bottom scour structure is common in the Chang 8 oil-bearing member of this area. e scour structure is often developed between the overlying coarse-grained sediment and the underlying fine-grained sediment.…”

Section: Sedimentary Characteristicsmentioning

confidence: 77%

“…Luo et al [8] and Chu et al [9] suggested that the oil and gas generated in Chang 7 is driven into the overlying Chang 6 and Chang 4 + 5 members and the underlying Chang 8 member by two-way hydrocarbon expulsion through overpressure. Chen et al [10] and Xia et al [11] considered that the argillaceous interlayer between a source and reservoirs hinders the migration of crude oil, and the later fault activity connects and changes the previously formed reservoirs. All these results agree with the oil exploration theories of "source control" and " high quality reservoir" [12,13], which means that the main controlling factors of oil reservoir are "thick sand belt" and "reservoir sweet spot (the part of the reservoir with higher porosity and permeability).…”

Section: Introductionmentioning

confidence: 99%

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Characteristics and Controlling Factors of the Chang 8 Oil Reservoir in the Yanchi Area of the Ordos Basin: A Case Study of Well G20

et al. 2022

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In the Ordos Basin, the Chang 8 oil reservoir of the Triassic Yanchang Formation is the main target of oil exploration and development and there are many factors affecting the hydrocarbon accumulation. Well G20 is an important exploration well in the Yanchi area in the northwestern part of the basin, and the core of the Chang 8 reservoir was sampled and tested to determine the source rocks, trace element composition, mineral composition, reservoir physical properties, and oil-bearing properties. The results show that the rock retrieved exhibits delta plain subfacies; the range of the Chang 8 water body was large, with a gentle slope, and the climate was relatively dry. These findings suggest that this reservoir was deposited in an environment in which sedimentary sand body could easily form. The Chang 8 sandstone reservoir pores are dominated by intergranular pores and feldspar intragranular dissolution pores, indicating that the Chang 8 reservoir is a low-porosity and low-permeability reservoir. Chang 7 source rocks from this area have a type I-II1 hydrocarbon-generating potential, with an average total organic carbon (TOC) content of 5.99% and vitrinite reflectance (Ro) value of 0.48%. Combined with the regional sedimentary evolution, tectonic movement, and reservoir distribution, it is considered that due to the lack of lithologic traps or low-amplitude structural traps, G20 produced water in well testing. The Chang 8 oil reservoir in the Yanchi area can be divided into structural reservoirs and structural-lithologic reservoirs. The conventional oil and gas reservoir exploration ideas of “thick sand belt” and “reservoir sweet spot” are not applicable here. The lithology traps or low-amplitude structural traps and areas with good preservation conditions are the main directions for the next phase of exploration in the northwestern part of the Ordos Basin.

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Section: Sedimentary Characteristicsmentioning

confidence: 77%

Section: Introductionmentioning

confidence: 99%

Characteristics and Controlling Factors of the Chang 8 Oil Reservoir in the Yanchi Area of the Ordos Basin: A Case Study of Well G20

et al. 2022

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“…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%

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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“…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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Reservoir space type and storage capacity of Oligocene lacustrine carbonate in the Yingxi area of western Qaidam Basin, China

Cited by 6 publications

References 15 publications

Characteristics and Controlling Factors of the Chang 8 Oil Reservoir in the Yanchi Area of the Ordos Basin: A Case Study of Well G20

Characteristics and Controlling Factors of the Chang 8 Oil Reservoir in the Yanchi Area of the Ordos Basin: A Case Study of Well G20

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

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