The formation mechanism of authigenic chlorite in tight sandstone and its effect on tight oil adsorption during hydrocarbon filling

Zhou, Qing; Li, Chao; Chen, Guojun; Lyu, Chengfu; Qu, Xuefeng; Ma, Xiaofeng; Li, Chengze; Lei, Qihong; Xie, Qiang

doi:10.2516/ogst/2021015

Cited by 5 publications

(4 citation statements)

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“…Core flow-through methods possess the advantage of displacing tight oils in connected micron pores [18,31]. However, they cannot separate the tight oil that exists in nanoscale pores or is adsorbed on mineral surfaces.…”

Section: Extraction Of Tight Oil From Sandstonesmentioning

confidence: 99%

“…Minerals serve as the foundation for various reservoir spaces, and intricate oil-rock interactions are crucial to the formation of tight oil in sandstones [31,39,[48][49][50]. Through the examination and analysis of core samples and thin sections (TSs), it was determined that the Chang 8 Member of the Yanchang Formation in the Ordos Basin predominantly consisted of black/dark gray fine/medium debris/feldspar and fine feldspar/debris sandstones.…”

Section: Mineral Compositionmentioning

confidence: 99%

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The Micro-Occurrence Mechanisms of Tight Oil: Fluid–Rock Interactions at Microscale Pores, Nanoscale Pores, and Mineral Surfaces

et al. 2023

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Understanding the micro-occurrence mechanism of tight oil has long been a daunting challenge in the exploration and development of unconventional resources. This article discusses the micro-occurrence mechanism of tight oil through continuous extraction by combining thin casting, fluorescent thin sections, environmental scanning electron microscope observations, physical property testing, and X-ray diffraction experiments. The results indicated that in the tight sandstone of the Chang 8 Formation in the Ordos Basin, the average tight oil content was 35.46% for microscale pores, 35.74% for nanoscale pores, and 28.79% for mineral surfaces. Six types of micro-occurrence states of tight oil were identified: emulsion, cluster, throat, star-like, isolation, and thin film forms. Although clay minerals and heavy components dominate the adsorption of tight oil on mineral surfaces, micro-occurrence is fundamentally an oil–rock interaction process. Hence, oil–rock interactions and occurrence states were combined in this study to identify tight oil’s micro-occurrence mechanism. The van der Waals forces of attraction between asphaltene molecules and a mineral surface play a critical role, and minerals with hydroxyl groups can also combine with carboxyl and hydroxyl groups present in tight oil. As a consequence of the adsorption of heavy components by minerals, tight oil components remain in microscale and nanoscale pores with a higher saturation, increased aromatic hydrocarbon content, and greater fluidity. The heterogeneity of the components due to adsorption influences the physical properties and mineralization framework of tight oil reservoirs. These findings suggest that tight oil occurrence results from the coupling of microscopic occurrence and component heterogeneity in microscale and nanoscale pores.

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Section: Extraction Of Tight Oil From Sandstonesmentioning

confidence: 99%

Section: Mineral Compositionmentioning

confidence: 99%

The Micro-Occurrence Mechanisms of Tight Oil: Fluid–Rock Interactions at Microscale Pores, Nanoscale Pores, and Mineral Surfaces

et al. 2023

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“…In this experiment, the occurrence morphology of tight oil in fresh samples was analyzed by the FTS and ESEM [6,24,[31][32][33][34][35]. According to the difference in position and shapes of adsorbed tight oil, the occurrence morphology of adsorbed tight oil in the study area was divided into five types, including the emulsion form, cluster form, throat form, thin-film form, and isolation form (Table 2 and Figure 4).…”

Section: Microoccurrence States Of Adsorbed Tightmentioning

confidence: 99%

Insights into the Effect of Micropore Structure and Mineralogy on Adsorbed Tight Oil in the Huaqing Area, Ordos Basin, China

Zhou

Zhang

et al. 2023

Geofluids

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There is great potential for tight oil as an alternative to conventional fossil fuels throughout the world. Adsorption, mineralogy, and pore structure of tight sandstone are very important factors for the efficient development of adsorbed tight oil from tight sandstone oil reservoirs. In this study, the occurrence morphology of tight oil adsorbed to varying pore structures was examined, as well as the relationship between adsorption content and occurrence morphology. X-ray energy dispersive spectra, environmental scanning electron microscope observations, and thin fluorescence sections were used to describe the occurrence morphology of adsorbed tight oil in tight sandstone reservoirs. It was found that adsorbed tight oil can be classified into five types: emulsion, cluster, throat, thin-film, and isolation, with average contents of 34.9%, 14.5%, 3.1%, 42.7%, and 4.7%, respectively. In addition, a Soxhlet extraction was developed with four pore structures to describe the geological effects of adsorbed tight oil in reservoirs. The adsorption content of tight oil ranges from 4.015 mg/g to 16.987 mg/g, with an average of 10.115 mg/g. The order of adsorption content for different occurrence morphologies is as follows: emulsion form > throat form > cluster form > isolation form > thin-film form. It is the size and connectivity of the porous throat that determines the desorption efficiency of tight oil. An important outcome of this study can be the introduction of rational development plans and the improvement of oil recovery efficiency for tight oil reservoirs.

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“…This study enhanced the understanding of low-medium geothermal reservoirs in Binhai district, Tianjin, China. Zhou et al [9] studied the formation mechanism of authigenic chlorite in tight sandstone and its effect on tight oil adsorption during hydrocarbon filling in Yanchang Formation, southwest region of Ordos Basin, China.…”

mentioning

confidence: 99%

Subsurface fluid injection and energy storage

Kühn

2021

Oil Gas Sci. Technol. – Rev. IFP Energies nouvelles

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The formation mechanism of authigenic chlorite in tight sandstone and its effect on tight oil adsorption during hydrocarbon filling

Cited by 5 publications

References 29 publications

The Micro-Occurrence Mechanisms of Tight Oil: Fluid–Rock Interactions at Microscale Pores, Nanoscale Pores, and Mineral Surfaces

The Micro-Occurrence Mechanisms of Tight Oil: Fluid–Rock Interactions at Microscale Pores, Nanoscale Pores, and Mineral Surfaces

Insights into the Effect of Micropore Structure and Mineralogy on Adsorbed Tight Oil in the Huaqing Area, Ordos Basin, China

Subsurface fluid injection and energy storage

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