Laboratory Characterization of Shale Oil Storage Behavior: A Comprehensive Review

Wu, Tonghao; Pan, Zhejun; Liu, Bo; Connell, Luke D.; Sander, Regina; Fu, Xiaofei

doi:10.1021/acs.energyfuels.0c04082

Cited by 31 publications

(17 citation statements)

References 103 publications

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“…The occurrence states of shale oil mainly include the free state and adsorbed state (or mutually soluble state). ,− There is no unified agreement on quantitative evaluation methods of free oil and adsorbed oil at present. The commonly used methods include sequential extraction with different polar solvents, novel Rock-Eval pyrolysis methods, , and numerical analyses of rock pyrolysis peaks .…”

Section: Resultsmentioning

confidence: 99%

Shale Oil and Gas Generation Process and Pore Fracture System Evolution Mechanisms of the Continental Gulong Shale, Songliao Basin, China

Sun

Feng

et al. 2022

Energy Fuels

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Continental shale oil is a new source of oil, and its formation and evolution mechanism is one of the most important scientific problems in its effective exploration and development. In this work, the hydrocarbon generation mechanism, occurrence of oil and gas, and pore structure characteristics were studied through a series of pyrolysis experiments using an improved closed experimental system, combined with chloroform extraction, two-dimensional nuclear magnetic resonance, and computed tomography, for the continental Gulong Shales, Songliao Basin. The results show that hydrocarbon generation from organic matter of continental Gulong shale follows a sequential reaction model, with adsorbed oil as an “intermediate” at Ro of 0.9–1.1%. The free oil reaches the generation peak and begins to convert to natural gas, and the gas/oil ratio increases rapidly when Ro > 1.3%. These suggest that the favorable oil generation window for Gulong shale is that Ro is between 0.9 and 1.6%. With oil generation, the shale pore structure and permeability change with maturity accordingly. The corresponding Ro for rapid porosity and pore volume increase is 0.9–1.2%, while Ro is greater than 1.2% for rapid permeability change as a result of the large amount of adsorbed oil converting into free oil. It is found that hydrocarbon generation and pore-forming materials are mostly lamalginite and the organic-clay complex, and their volumes shrank while generating hydrocarbon, forming pores and fractures along the layers and “sponge-like” pores, respectively. When Ro > 1.2%, the shale oil generation peak, pore development peak, and overpressure evolution peak are coupled, providing favorable conditions for shale oil and gas enrichment in continental Gulong shale. These experimental findings mutually prove and confirm the practice of Gulong shale oil exploration, and it may have important theoretical and practical significance for continental shale oil exploration and discovery in other basins.

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Section: Resultsmentioning

confidence: 99%

Shale Oil and Gas Generation Process and Pore Fracture System Evolution Mechanisms of the Continental Gulong Shale, Songliao Basin, China

Sun

Feng

et al. 2022

Energy Fuels

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“…Accordingly, the organic matter (Figure 12b,d) shows the strongest adsorption capacity for oil followed by clay minerals (Figure 12d), quartz (Figure 12c), and calcite. 76 The results in this study are significant to the comprehensive understanding of pore-fracture network development in the mixed lacustrine source rock system.…”

Section: Full-scalementioning

confidence: 81%

Role of Organic Matter, Mineral, and Rock Fabric in the Full-Scale Pore and Fracture Network Development in the Mixed Lacustrine Source Rock System

et al. 2022

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The mixed deposition constitutes the external clastic, intrabasinal, and pyroclastic components in both marine and lacustrine environments. The finegrained mixed lacustrine source rocks are rich in organic matter and present good unconventional energy resources. However, the mixed lacustrine source rock systems have extremely low permeabilities and need hydraulic fracturing to stimulate oil from the complex nanoscale matrix. The role of rock fabric, organic matter, and mineral compositions in full-scale pore structures is still unclear, especially for the source rock from a mixed sedimentary environment. This restricts sweet spot identification. Here, we use three groups of Permian Lucaogou source rock samples with fine laminated, thick laminated, and massive rock fabric to investigate the relationship between rock fabric, organic matter, and pore structure using a combination of mineralogy, organic geochemistry, low-pressure nitrogen adsorption, micro-CT, and mercury injection capillary pressure data. The results indicate that the Lucaogou source rocks mainly contain type I and type II kerogen and show good to excellent hydrocarbon generation potential. The source rock was deposited in a mixed environment with high contents of carbonate and less siliceous minerals, showing good frackability. The mineralogy-based ternary classification shows that the source rock mainly belongs to high total organic carbon (TOC > 4%) mixed carbonate mudstone and high TOC mixed mudstone. For mixed lacustrine source rock, the full-scale pore-fracture distribution shows that the average percentage values of pore volume for micropores (<10 nm), transitional pores (10−100 nm), mesopores (100−1000 nm), and macropores (fracture) (>1000 nm) are 11.14, 21.62, 10.77, and 56.47%, respectively. However, the average percentage values of pore surface area for the abovementioned pores are 62.45, 30.45, 5.47, and 1.63%, respectively. Both quartz and terrigenous clast present a weak-medium unimodal correlation with the TOC content. Both terrigenous clast and clay minerals control the source rock hydrocarbon generation potential. The carbonate and terrigenous clast mineral content play a significant role in micropores and transitional pores, while the clay mineral presents a negative impact on macropore development. The effect of rock fabric on shale oil potential is negligible compared with organic matter abundance. Shales with thick parallel laminae and medium TOC (2% < TOC < 4%) possess favorable shale oil potential.

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“…The shale is dominated by nanosized pore system, therefore, the interaction of fluids and pores is prominent, in other words, the influence of the adsorption of mineral particles on shale oil retention is of importance Wu et al, 2021). Generally, the adsorption between oil and mineral surfaces is attributed to physical interactions (such as van der Waals forces, and hydrogen bonds) or chemical interactions (Yusupova et al, 2002;Dudášová et al, 2008;Cui and Cheng, 2017;Cao et al, 2020).…”

Section: Retention Mechanism Of Shale Oilmentioning

confidence: 99%

Oil Retention in Shales: A Review of the Mechanism, Controls and Assessment

et al. 2021

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Shale oil is a vital alternative energy source for oil and gas and has recently received an extensive attention. Characterization of the shale oil content provides an important guiding significance for resource potential evaluation, sweet spot prediction, and development of shale oil. In this paper, the mechanism, evaluation and influencing factors of oil retention in shales are reviewed. Oil is retained in shales through adsorption and swelling of kerogen, adsorption onto minerals and storage in shale pores. Quite a few methods are developed for oil content evaluation, such as three-dimensional fluorescence quantitation, two-dimensional nuclear magnetic resonance (2D NMR), solvent extraction, pyrolysis, multiple extraction-multiple pyrolysis-multiple chromatography, logging calculation, statistical regression, pyrolysis simulation experiment, and mass balance calculation. However, the limitations of these methods represent a challenge in practical applications. On this basis, the influencing factors of the oil retention are summarized from the microscale to the macroscale. The oil retention capacity is comprehensively controlled by organic matter abundance, type and maturity, mineral composition and diagenesis, oil storage space, shale thickness, and preservation conditions. Finally, oil mobility evaluation methods are introduced, mainly including the multitemperature pyrolysis, 2D NMR, and adsorption-swelling experiment, and the influencing factors of movable shale oil are briefly discussed. The aim of this paper is to deepen the understanding of shale oil evaluation and provide a basis for further research.

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Laboratory Characterization of Shale Oil Storage Behavior: A Comprehensive Review

Cited by 31 publications

References 103 publications

Shale Oil and Gas Generation Process and Pore Fracture System Evolution Mechanisms of the Continental Gulong Shale, Songliao Basin, China

Shale Oil and Gas Generation Process and Pore Fracture System Evolution Mechanisms of the Continental Gulong Shale, Songliao Basin, China

Role of Organic Matter, Mineral, and Rock Fabric in the Full-Scale Pore and Fracture Network Development in the Mixed Lacustrine Source Rock System

Oil Retention in Shales: A Review of the Mechanism, Controls and Assessment

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