Organic matter transformation ratio, hydrocarbon expulsion efficiency and shale oil enrichment type in Chang 73 shale of Upper Triassic Yanchang Formation in Ordos Basin, NW China

Zhao, Wenzhi; Bian, Congsheng; Li, Yong-Xin; Wei, Liu; DONG, Jin; Wang, Kun; ZENG, Xu

doi:10.1016/s1876-3804(22)60366-5

Cited by 20 publications

(17 citation statements)

References 13 publications

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“…where V ϕ−r is the pore volume at a certain pressure, nm 3 . α is the Biot coefficient, dimensionless.…”

Section: Pore Deformation Modelmentioning

confidence: 99%

“…Δσ ̅ is the average normal stress acting on the pore space, MPa. V ϕ−r is pore volume at a certain pressure, nm 3 . α is the Biot coefficient, dimensionless.…”

Section: Pore Deformation Modelmentioning

confidence: 99%

“…where ΔV ϕ is the variation of pore volume, nm 3 . V ϕ−0 is the pore volume under surface pressure, nm 3 . ϕ is porosity, dimensionless.…”

Section: Pore Deformation Modelmentioning

confidence: 99%

“…Shale oil is widely distributed in the world, and the statistics of resource potential evaluation results from 116 basins worldwide reveal that the total technically recoverable resources of shale oil are about 251.2 billion tons, with huge development potential. − The development process of such tight reservoir is subject to the coupling effect of multiple factors, resulting in the deformation of nanopores. − Shale oil reservoir nanoscale pore deformation is mainly under the coupling effect of stress motivation and adsorption motivation deformation. − The indoor experimental analysis, numerical simulation methods, and micromechanical analytical equation analysis are the stress motivation pore deformation research field. − The experimental analysis method is mainly based on the results of experiments. Moreover, the empirical mathematical model of porosity and permeability variation with pore pressure at the macroscopic scale is obtained by fitting the data. − However, such models still contain certain empirical parameters and have a relatively poor applicability for microscopic scales.…”

Section: Introductionmentioning

confidence: 99%

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Study on the Nanopore Deformation Mechanisms in Shale Oil Reservoir: Insights from the Molecular Simulation

Lei,

Dou,

Hong

et al. 2023

ACS Omega

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The stress and adsorption motivation deformation during shale oil production directly affect its development dynamics. First, a mathematical simulation of pore deformation in shale oil under stress motivation is established. We analyzed the impact of factors including the reservoir pressure, Biot coefficient, bulk modulus, and tortuosity on the deformation characteristics of nanopores. Second, a pore deformation model under multifactor synergistic effect is derived by combining the molecular dynamics, which takes into account the influence of adsorption deformation on the total adsorption of shale oil reservoir. Finally, a shale oil pore deformation model under multifactor synergistic effect is obtained. The results show that the current pore diameter shows a trend of decreasing with the decrease of current formation pressure and the difference with original reservoir pressure increases. The pore shows a trend of less deformation with a decrease in the effective stress coefficient. When the Biot coefficient is 0.8, the pore diameter under 5 MPa is 4.01 nm. When the Biot coefficient decreases to 0.3, the pore diameter under 5 MPa becomes 9.12 nm, an increase of 127.43% compared to 4.01 nm. The bulk modulus affects the magnitude of pore deformation under the same pressure, which means that the pore diameter shows a tendency to deform more easily as the bulk modulus increases. Meanwhile, the pore diameter decreases with increasing tortuosity. In addition, the pore deformation is subject to both stress and adsorption motivation deformation synergistically. The stress motivation deformation leads to a decrease of pore diameter with pressure decrease, while, in contrast, the adsorption motivation leads to an increase of pore diameter. The pore diameter under synergy is influenced by the coupling effect, and the deformation under synergy tends to decrease as the pore diameter decreases. When the rock mechanical parameters are changed so that the pores are not easily deformed by stress, the adsorption motivation deformation plays a dominant role in synergy. The amount of synergistic deformation decreases with increasing temperature, while the change in the component ratio of multicomponent fluid mainly affects the corresponding adsorption and the amount of synergistic deformation. Interestingly, when the proportion of CO 2 is the largest, the corresponding maximum deformation is higher than the other proportions (43.77%). It not only enhances the recovery rate of shale oil reservoirs by utilizing CO 2 but also provides the possibility of geological CO 2 burial.

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“…where V ϕ−r is the pore volume at a certain pressure, nm 3 . α is the Biot coefficient, dimensionless.…”

Section: Pore Deformation Modelmentioning

confidence: 99%

“…Δσ ̅ is the average normal stress acting on the pore space, MPa. V ϕ−r is pore volume at a certain pressure, nm 3 . α is the Biot coefficient, dimensionless.…”

Section: Pore Deformation Modelmentioning

confidence: 99%

“…where ΔV ϕ is the variation of pore volume, nm 3 . V ϕ−0 is the pore volume under surface pressure, nm 3 . ϕ is porosity, dimensionless.…”

Section: Pore Deformation Modelmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Study on the Nanopore Deformation Mechanisms in Shale Oil Reservoir: Insights from the Molecular Simulation

Lei,

Dou,

Hong

et al. 2023

ACS Omega

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“…Shale oil evaporative loss is evidenced by a marked difference in S 1 values between fresh samples (collected with proper sealing or protective measures) and old samples (where S 1 stabilizes over time) (Bhosle et al, 2015;Jiang, Chen, et al, 2016). Zhao et al (2023) measured an average S 1 value of approximately 10.2 mg/g for fresh Chang7 shale samples, while the average S 1 value for old samples was about 4.58 mg/g, resulting in a 55% loss in S 1 (Figure 10). This indicates that Chang7 shale samples experienced evaporative losses during storage and experimentation.…”

Section: Characteristics Of Petroleum Lossmentioning

confidence: 99%

Impact of petroleum expulsion and evaporation losses on shale oil assessment using pyrolysis techniques

You,

Liu,

Song

et al. 2023

Geological Journal

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Shale reservoirs contain petroleum that undergoes losses through oil expulsion and evaporation, with uncertain implications on shale oil reserves and mobility evaluation. This study focuses on understanding the influence of these losses on open‐system pyrolysis, the primary method for assessing shale oil content and mobility. Comprehensive analyses were performed on 26 lacustrine shale samples from the Chang7 Member, encompassing total organic carbon (TOC), programmed pyrolysis, solvent extraction, and gas chromatography–mass spectrometry (GC–MS). The research examines the impact of petroleum losses on petroleum fractions, the oil saturation index (OSI), and multi‐step pyrolysis outcomes. The findings indicate that Chang7 shale with TOC content above 7% experiences more substantial petroleum losses than those with TOC below 7%. Petroleum losses result in significant fractional distillation of crude oil in the shale, leading to the deterioration of shale oil properties and a notable reduction in free oil content in S1, ultimately causing a decline in OSI values. As a result, Chang7 shale with TOC below 7% demonstrates a higher potential for shale oil recovery, whereas Chang7 shale with TOC exceeding 7% should be considered more significant as a hydrocarbon source rock. Moreover, multi‐step pyrolysis is not suitable for assessing petroleum mobility in shale with low free oil content (OSI values below 100 mg/g). This limitation arises from the loss of free low‐boiling components in Chang7 shale, and the currently detected low‐boiling pyrolysis products may predominantly exist in an adsorbed state.

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Progress in Core Engineering Technology of Gulong Shale Oil

Kong

2024

Springer Series in Geomechanics and Geoengineering

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Organic matter transformation ratio, hydrocarbon expulsion efficiency and shale oil enrichment type in Chang 73 shale of Upper Triassic Yanchang Formation in Ordos Basin, NW China

Cited by 20 publications

References 13 publications

Study on the Nanopore Deformation Mechanisms in Shale Oil Reservoir: Insights from the Molecular Simulation

Study on the Nanopore Deformation Mechanisms in Shale Oil Reservoir: Insights from the Molecular Simulation

Impact of petroleum expulsion and evaporation losses on shale oil assessment using pyrolysis techniques

Progress in Core Engineering Technology of Gulong Shale Oil

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