Deep-Lacustrine Shale Heterogeneity and Its Impact on Hydrocarbon Generation, Expulsion, and Retention: A Case Study from the Upper Triassic Yanchang Formation, Ordos Basin, China

Fan, Bojiang; Shi, Liang

doi:10.1007/s11053-018-9387-2

Cited by 12 publications

(14 citation statements)

References 30 publications

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“…Due to prolong sedimentation, diagenesis, structure and other multi-type, multi-stage evolutionary effects of geological history, shale reservoirs develop extremely complex and heterogeneous pore systems (Fan and Liang 2019;Tang et al 2019;Yang et al 2016). It can be observed in the argon-ion polished scanning electron microscope image of shale rich in organic matter in the Longmaxi Formation, south Sichuan, that cylindrical pores, slit-shaped pores and slit-shaped pores with marginal grooves are ubiquitous in the reservoir.…”

Section: Modelsmentioning

confidence: 99%

Simulation of methane adsorption in diverse organic pores in shale reservoirs with multi-period geological evolution

Chen

Zhang

et al. 2021

Int J Coal Sci Technol

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In shale reservoirs, the organic pores with various structures formed during the thermal evolution of organic matter are the main storage site for adsorbed methane. However, in the process of thermal evolution, the adsorption characteristics of methane in multi type and multi-scale organic matter pores have not been sufficiently studied. In this study, the molecular simulation method was used to study the adsorption characteristics of methane based on the geological conditions of Longmaxi Formation shale reservoir in Sichuan Basin, China. The results show that the characteristics of pore structure will affect the methane adsorption characteristics. The adsorption capacity of slit-pores for methane is much higher than that of cylindrical pores. The groove space inside the pore will change the density distribution of methane molecules in the pore, greatly improve the adsorption capacity of the pore, and increase the pressure sensitivity of the adsorption process. Although the variation of methane adsorption characteristics of different shapes is not consistent with pore size, all pores have the strongest methane adsorption capacity when the pore size is about 2 nm. In addition, the changes of temperature and pressure during the thermal evolution are also important factors to control the methane adsorption characteristics. The pore adsorption capacity first increases and then decreases with the increase of pressure, and increases with the increase of temperature. In the early stage of thermal evolution, pore adsorption capacity is strong and pressure sensitivity is weak; while in the late stage, it is on the contrary.

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Section: Modelsmentioning

confidence: 99%

Simulation of methane adsorption in diverse organic pores in shale reservoirs with multi-period geological evolution

Chen

Zhang

et al. 2021

Int J Coal Sci Technol

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“…sandstone interbedding stratum, the more frequent the shalesandstone configuration and the lower the retention of oil in the shale (Fan and Shi, 2019), while the oil-bearing properties of the interlayers (i.e., the sandstone seams) within the shale seams are improved (Raji et al, 2015). Exploration practices have verified that fault systems impart complementary control effects on both conventional and shale reservoirs, the retained oil in the shale may migrate to the shallow layers along the faults remaining active, which is unfavorable for shale oil enrichment (Fu et al, 2020;Liu B. et al, 2021).…”

Section: Influences Of Shale Thickness and Preservation Conditions On Oil Retentionmentioning

confidence: 99%

“…Microfractures extending only in the interior of a shale increase the shale oil storage space and fluidity, which is more benefit to shale oil enrichment . Therefore, the shale thickness plays a positive role in the oil-bearing capacity (Fan and Shi, 2019;Zhao W. Z. et al, 2021).…”

Section: Influences Of Shale Thickness and Preservation Conditions On Oil Retentionmentioning

confidence: 99%

“…Their results revealed that the movable oil content first increases and then decreases with the content of clay minerals (25% as the inflection point) and quartz minerals (15% as the inflection point), which depends on the coupling effect of the mineral content on the porosity, adsorption capacity and TOC content. In addition, due to the petroleum fractionation effect, feldsparquartz or carbonate laminae interbedded with organic-rich laminae at the microscale and interbedded shale, sandstone, carbonate, and mixed rock layers in shale strata at the macroscale contain more light oil components that easily flow (Jarvie, 2014;Fan and Shi, 2019;Pan et al, 2019;Liu B. et al, 2021).…”

Section: Influencing Factors Of Movable Oilmentioning

confidence: 99%

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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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“…Yuan et al [24] studied the mechanism of organic matter deposition and enrichment, pointing out that tectonism played a role in organic carbon enrichment and deposition, and that the increase of primary productivity caused by volcanism could play a role in the accumulation of carbonaceous sediments. Fan et al [25] analyzed the influence of formation heterogeneity on hydrocarbon generation, retention, and expulsion. Chen, Sun, et al [26,27] studied the controlling factors of shale oil transportation and distribution.…”

Section: Introductionmentioning

confidence: 99%

The Effect of Hydration on Pores of Shale Oil Reservoirs in the Third Submember of the Triassic Chang 7 Member in Southern Ordos Basin

et al. 2019

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Shale oil is an unconventional kind of oil and gas resource with great potential. China has huge reserves of shale oil, and shale oil resources are abundant in the third submember of the Triassic Chang 7 member in the southern Ordos Basin. At present, this area is in the initial stage of shale oil exploration and development. The reservoir pore is one of the key factors affecting oil accumulation, drilling safety, and oil production. It is also an important reservoir parameter that must be defined in the exploration stage. In general, the clay content in the shale section is high, and is prone to hydration. In order to study the effect of fluid on the pore type, structure, and distribution of shale oil reservoirs, experiments using X-ray diffraction, a porosity-permeability test, mercury porosimetry, rock casting thin section, and scanning electron microscopy were carried out. The experimental results show that the content of clay and quartz is very high in the studied formation. The pore porosity and permeability of the rock is highly heterogeneous because of the obvious stratigraphic bedding and interbeds. Microstructural observation of rocks shows that the main pore types are intergranular pores, intragranular pores, intercrystalline pores, and organic pores. Crack types are dissolution cracks, contraction cracks of organic matter, and abnormal pressure structural cracks. After hydration, the porosity of rock will increase in varying degrees, and pore size, pore content in different sizes, and pore structure will also change. The results show that the pores of tuff mainly changes at the initial stage of hydration, and the pore change of tuff is the most obvious within 6 hours of soaking in clear water. The influence of hydration on the pore of shale is greater than that of tuff, but the main change stage is later than tuff, and the pore change of shale is the most obvious within 12 to 24 hours of soaking in clear water. The soaking experiment of water-based drilling fluid (WBM-SL) shows that it can plug a certain size of holes and cracks and form a protective layer on the rock surface, thus effectively reducing hydration. In actual construction, multisized solid particles should be allocated in drilling fluid according to the formation pore's characteristics, and the stability of the protective layer should be guaranteed. This can reduce the accident of well leakage and collapse and is conducive to the efficient and safe development of shale oil.

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Deep-Lacustrine Shale Heterogeneity and Its Impact on Hydrocarbon Generation, Expulsion, and Retention: A Case Study from the Upper Triassic Yanchang Formation, Ordos Basin, China

Cited by 12 publications

References 30 publications

Simulation of methane adsorption in diverse organic pores in shale reservoirs with multi-period geological evolution

Simulation of methane adsorption in diverse organic pores in shale reservoirs with multi-period geological evolution

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

The Effect of Hydration on Pores of Shale Oil Reservoirs in the Third Submember of the Triassic Chang 7 Member in Southern Ordos Basin

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