Using laser scanning confocal microscopy combined with saturated oil experiment to investigate the pseudo in-situ occurrence mechanism of light and heavy components of shale oil in sub-micron scale

Gao, Zhiye; Duan, Longfei; Jiang, Zhenxue; Huang, Liliang; Chang, Jiaqi; Zheng, Guowei; Wang, Zhiwei; An, Feng Chen; Wei, Weihang

doi:10.1016/j.petrol.2022.111234

Cited by 14 publications

(9 citation statements)

References 64 publications

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“…Laser scanning confocal microscopy (LSCM) utilizes a laser spot as a fluorescence excitation light for continuous scanning of samples, blocking the out-of-focus plane light through spatially conjugated diaphragms (pinholes) and imaging [91]. LSCM offers a high level of detail, with the ability to magnify up to 10,000 times and achieve an ultimate resolution of 0.15 µm.…”

Section: Laser Scanning Confocal Microscopymentioning

confidence: 99%

Microscopic Characterization and Fractal Analysis of Pore Systems for Unconventional Reservoirs

Guan,

Cai,

et al. 2024

JMSE

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The complex pore structure of unconventional oil and gas reservoirs is one of the reasons for the difficulties in resource evaluation and development. Therefore, it is crucial to comprehensively characterize the pore structure, understand reservoir heterogeneity from multiple perspectives, and gain an in-depth understanding of fluid migration and accumulation mechanisms. This review outlines the methods and basic principles for characterizing microporous systems in unconventional reservoirs, summarizes the fractal analysis corresponding to the different methods, sorts out the relationship between the fractals and reservoir macroscopic physical properties (porosity, permeability, etc.) with the reservoir microscopic pore structures (pore structure parameters, pore connectivity, etc.). The research focuses on cutting-edge applications of characterization techniques, such as improved characterization accuracy, calibration of PSD ranges, and identification of different hydrogen compositions in pore systems for dynamic assessment of unconventional reservoirs. Fractal dimension analysis can effectively identify the quality level of the reservoir; complex pore-throat structures reduce permeability and destroy free fluid storage space, and the saturation of removable fluids is negatively correlated with Df. As for the mineral composition, the fractal dimension is positively correlated with quartz, negatively correlated with feldspar, and weakly correlated with clay mineral content. In future qualitative characterization studies, the application and combination of contrast agents, molecular dynamics simulations, artificial intelligence techniques, and 4D imaging techniques can effectively improve the spatial resolution of the images and explore the adsorption/desorption of gases within the pores, and also help to reduce the computational cost of these processes; these could also attempt to link reservoir characterization to research on supercritical carbon dioxide-enhanced integrated shale gas recovery, carbon geological sequestration, and advanced underground hydrogen storage.

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Section: Laser Scanning Confocal Microscopymentioning

confidence: 99%

Microscopic Characterization and Fractal Analysis of Pore Systems for Unconventional Reservoirs

Guan,

Cai,

et al. 2024

JMSE

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“…On the one hand, the difference in oiliness between the adjacent laminae was related to the difference in mineral composition and the pore space of the different types of laminae. On the other hand, it can be attributed to the micromigration of the shale oil between laminae as many of the light hydrocarbon components were migrated, through bedding cracks [33], from the organic-rich argillaceous laminae migrates to the adjacent silty laminae shale or felsic laminae.…”

Section: Oil-bearing Characteristics Of the Shale-oil Sweet Spotsmentioning

confidence: 99%

Characteristics and Key Controlling Factors of the Interbedded-Type Shale-Oil Sweet Spots of Qingshankou Formation in Changling Depression

Yang,

Xing,

Xue

et al. 2023

Energies

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Different types of shale-oil sweet spots have developed and are vertically stacked in multiple layers of the Qingshankou Formation in the Changling Depression, southern Songliao Basin. Furthermore, this area lacks a classification standard in the optimization of its shale-oil sweet-spot area/layers. Through relevant tests of the region in question’s organic geochemistry, physical properties, oiliness, and pore structure, this paper investigates the formation elements of shale-oil sweet spots. In addition, summaries of its enrichment-controlling factors are given, and the classification standard and evaluation method for understanding the comprehensive sweet spots of the interbedded-type shale oil are then established. The interbedded-type shale oil is enriched in the Qingshankou I Member in the Changling Depression, and it has the features of medium-to-high maturity, the development of inorganic pores and micro-cracks, as well as higher oil saturation and better oil mobility. The sweet-spot enrichment is affected by lamina type, sedimentary facies, maturity, and sand–shale combinations. Both silty-laminated felsic shale and argillaceous-laminated felsic shale, which are developed in semi-deep lakes, are favorable shale lithofacies as they have excellent brittleness and oil mobility. The high maturity and the interbedded combination of sand and shale ensure the efficient production of shale oil, among which the pure-shale section issues a continuous contribution to the production process. Combined with oil testing, sweet-spot classification standards and a comprehensive evaluation of interbedded-type shale oil were established. An area of 639.2 km2 for the interbedded-type shale-oil sweet spots was preferred, among which type I (193 km2) belonged to the combination of “good shale and good siltstone interlayers adjacent”, and type II belonged to “good shale and medium siltstone interlayers adjacent” combination (which have long-term low and stable production prospects). The research provides theoretical guidance on the effective exploration and development of the shale oil of the Qingshankou Formation in the Changling Depression.

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“…27−30 LSCM can identify the occurrence characteristics of light and heavy components in shale oil at the submicron level, but the corresponding relationship between the occurrence characteristics of light and heavy components and the occurrence state must be further determined. 31,32 Indirect methods for characterizing shale oil occurrence states mainly include nuclear magnetic resonance (NMR), micro-nano computed tomography (CT), and multitemperature pyrolysis. NMR can obtain the relaxation time spectrum of fluids in different pores, 33 whereas the reliability of identifying different occurrence states must be further verified.…”

Section: Introductionmentioning

confidence: 99%

“…FTSO can distinguish different components of crude oil through fluorescence color but at low resolutions . Meanwhile, FE-SEM and ESEM can identify shale oil occurrence states on the basis of the morphology characteristics of mineral and fluid interfaces, but they cannot accurately distinguish between free and adsorbed shale oil. − LSCM can identify the occurrence characteristics of light and heavy components in shale oil at the submicron level, but the corresponding relationship between the occurrence characteristics of light and heavy components and the occurrence state must be further determined. , …”

Section: Introductionmentioning

confidence: 99%

Occurrence Mechanisms of Laminated-Type and Sandwich-Type Shale Oil in the Fengcheng Formation of Mahu Sag, Junggar Basin

Gong,

Bai,

Gao

et al. 2023

Energy Fuels

Self Cite

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The shale oil resources of the Permian Fengcheng Formation in the Mahu Sag are abundant, and the types of shale oil reservoirs therein are diverse. However, differences in the reservoir spaces, occurrence states, and source−reservoir configurations of different types of shale oil reservoirs restrict the in-depth understanding of the enrichment and accumulation mechanisms of shale oil in this formation. Thus, using multiple complementary experiments, this study systematically compared laminated-type and sandwich-type shale oil reservoirs (LTSOR and STSOR), in terms of hydrocarbon generation potential, physical characteristics, and oil-bearing properties. These two types of shale oil reservoirs had distinct differences in total organic carbon (TOC), porosity, oil saturation index, and S 1 , demonstrating differences in accumulation mechanisms. These two types of reservoirs were mainly dominated by inorganic intergranular pores and dissolution pores, and the storage capability of STSOR was much better than that of LTSOR. Specifically, STSOR mainly developed macropores, whereas LTSOR developed macropores and mesopores. The free oil content in the STSOR was found to be higher than that of the adsorbed oil, whereas the free and adsorbed oil contents in the LTSOR were similar. Furthermore, the shale oil occurrence in the STSOR was mainly affected by pore structure and mineral composition, whereas the shale oil occurrence in the LTSOR was affected by pore structure, mineral composition, TOC content, and sedimentary structure. The source−reservoir configuration relationship of STSOR was one where the upper and lower shale layers were source rocks, whereas the intercalated siltstone layers were reservoirs. The source−reservoir configuration of the LTSOR involved bright laminae as reservoirs and dark laminae as source rocks (i.e., integrated source and reservoir). Hydrocarbon accumulation models were established for the STSOR and LTSOR that involved source−reservoir configurations, occurrence states, and migration directions.

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Using laser scanning confocal microscopy combined with saturated oil experiment to investigate the pseudo in-situ occurrence mechanism of light and heavy components of shale oil in sub-micron scale

Cited by 14 publications

References 64 publications

Microscopic Characterization and Fractal Analysis of Pore Systems for Unconventional Reservoirs

Microscopic Characterization and Fractal Analysis of Pore Systems for Unconventional Reservoirs

Characteristics and Key Controlling Factors of the Interbedded-Type Shale-Oil Sweet Spots of Qingshankou Formation in Changling Depression

Occurrence Mechanisms of Laminated-Type and Sandwich-Type Shale Oil in the Fengcheng Formation of Mahu Sag, Junggar Basin

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