Microscale comprehensive evaluation of continental shale oil recoverability

Xu, Jinkai; Li, Guoxin; Meng, Siwei; Wang, Xiaoqi; Liu, Chang; Tao, Jiaping; Liu, He

doi:10.1016/s1876-3804(21)60021-6

Cited by 37 publications

(15 citation statements)

References 18 publications

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“…In August 2021, the discovery of Gulong shale oil was announced, and it attracted widespread attention due to its huge reserves (1.268 billion tonnes worth of geological reserves). The storage space of shale oil is highly heterogeneous, and the presence of hierarchical micro-nano pores has an important influence on the storage and transport of shale oil (Huai et al, 2020;Jin et al, 2021). Many classical theory and concepts, such as capillary condensation theory, multiphase seepage theory, contact line dynamics and contact angle are used to describe the mechanism of solid-liquidgas interactions and enhanced oil recovery, which has been proposed as one of the six key scientific problems in the production of Gulong shale oil (Sun et al, 2021).…”

Section: Introductionmentioning

confidence: 99%

“…Due to the small pore throat structure of shale oil reservoirs and the complex fluid phase state, the experimental investigations on shale oil have focused on the microscopic scale. To this end, Jin et al (2021) analyzed the distribution of movable shale oil using the charge effect of electron beams, which is an intuitive manifestation of the difference in electrical conductivity of the specimens. Generally, the pore size of Gulong shale reservoir ranges from 10 to 50 nm, which were measured by the mercury injection method.…”

Section: Introductionmentioning

confidence: 99%

“…However, field emission scanning electron microscopy observed the existence of shale oil in a pore with size of 9 nm, which breaks the knowledge that the lower limit of oil-bearing pore size is 20 nm (He et al, 2022). At the same time, important progresses have been made in multiscale digital core technologies such as mineral composition analysis and digital rock fracture propagation simulation (Jin et al, 2021). Because of the tight storage space of Gulong shale oil, the interface effect is expected to play a dominant role and the microscopic interactions between oil and reservoir matrix become quite important.…”

Section: Introductionmentioning

confidence: 99%

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Molecular modeling on Gulong shale oil and wettability of reservoir matrix

et al. 2022

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Understanding molecular interactions between oil and reservoir matrix is crucial to develop a productive strategy for enhanced oil recovery. Molecular dynamics simulation has become an important method for analyzing microscopic mechanisms of some static properties and dynamic processes. However, molecular modeling of shale oil and reservoir matrix is still challenging, due to their complex features. Wettability, which is the measurement of oilmatrix interactions, requires in-depth understanding from the microscopic perspective. In this study, the density, interfacial tension and viscosity of eleven common components in shale oil are calculated using molecular dynamics simulations. Then a molecular model of Gulong shale oil is built, based on the reported experimental results and simulations. Compared with the variation in hydrocarbon content, the change in polar component content leads to more significant variations in the physical properties of shale oil. This molecular model is also employed to investigate the wettability of shale-oil nanodroplets on minerals and organic matter, with or without the surrounding aqueous phase. This work suggests fresh ideas for studying the oil-matrix interactions on the nanoscale and provides theoretical guidance for shale oil exploitation.

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Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Molecular modeling on Gulong shale oil and wettability of reservoir matrix

et al. 2022

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“…A success of shale gas in North America started a "shale revolution" all over the world. In China, a strategic breakthrough on shale gas has also been made along with the sustained progress in exploration and development technologies [1][2][3][4][5][6]. In fact, China has the largest technically recoverable reserves in the world, and Sichuan Basin possesses the most abundant shale gas resources in China [7][8][9][10][11][12][13][14].…”

Section: Introductionmentioning

confidence: 99%

Mechanism of Forming Low Resistivity in Shale Reservoirs

Xie

Zhou

et al. 2022

Geofluids

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In the oil and gas industry, traditional logging mostly deems that oil and gas reservoirs are characterized by high resistivity, whereas the water layer is often by low resistivity. However, a lot of exploration and development practices on shale gas reservoirs in Sichuan Basin, China, prove that it is hard to characterize a functional relation between resistivity and water saturation using the Archie equation. Therefore, to make clear the mechanism to form low resistivity in shale gas reservoirs, the matrix resistivity was calculated through the percolation network simulation based on pore structure characteristics and mineral compositional parameters. Moreover, the resistivity in low-resistivity laminations of shale was measured through the finite element simulation. In addition, the reasons for such low resistivity in shale were analyzed according to the resistivity-forming mechanism, and the effects of penetration degree, width, quantity, and spatial distribution of the laminations on the resistivity were worked out. Those may provide theoretical support for explaining the phenomenon of low-resistivity gas reservoirs.

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“…Generally speaking, from the perspective of evaluation and economic development of medium-high maturity shale oil (Zhao et al, 2020a;Zhao et al, 2020b), thin layers of coarser rocks (e.g., siltstone and dolomitic siltstone) (Zhang et al, 2012) sandwiched between thick mudstone layers are sweet-spot layers. Rocks of different lithofacies have wide differences in geologic properties represented by the "7-petrophysical parameters" (Lu et al, 2018;Jin et al, 2021), and thus have different production features after fracturing.…”

Section: Introductionmentioning

confidence: 99%

Lithofacies Architecture and Distribution Patterns of Lacustrine Mixed Fine-Grained Rocks —a Case Study of Permian Lucaogou Formation in Jimsar Sag, NW China

Yin

Bin

et al. 2021

Front. Earth Sci.

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As the controlling effect of complex lithofacies of lacustrine mixed fine-grained rocks on the shale oil sweet spot remains unclear, core, outcrop, general logging, nuclear magnetic resonance (NMR) logging, testing, and production data were used to study the types, combination pattern, and genesis of lithofacies architectures of lacustrine mixed fine-grained rocks in the study area by lithofacies hierarchy analysis, X-ray fluorescence (XRF) logging, UAV, and 3D geological modeling. The research shows that: 1) According to lithology and sedimentary structure, the mixed fine-grained rocks can be divided into 13 lithofacies types of different origins in 5 sub-categories and 2 categories. 2) UAV photography was combined with a traditional field survey to characterize the 3D spatial distribution of lithofacies architecture of the Lucaogou Formation on the outcrop, and it is found that the lithofacies architecture patterns of mixed fine-grained rocks include three types: gradual change type, abrupt change type, and special type. The gradual change type with higher sand development degree and symmetrical lithofacies architecture has a high quality reservoir with dissolution pores, and is mixed beach-bar sand in the mixed zone. It is high in development degree and often appears as several similar cycles stacking over each other. The abrupt change type can be subdivided into two sub-types, asymmetric and smaller in reservoir thickness. It is very high in development degree and often comes in several similar cycles. The special type belongs to thick clastic rock relatively independent in the mixed fine-grained rocks with a high development degree of sand. The sand is a higher quality reservoir with properties of tight reservoir. It often appears as stacking of single cycle sand. 3) The different lithofacies architectures in the mixed fine-grained rocks have significant differences in distribution. The gradual change type is mainly composed of mudstone, dolomitic siltstone, and sandy dolomite, dolomitic siltstone, and mudstone, and appears in lenticular shape overlapping with each other on the plane. The abrupt change type is made up of felsic siltstone, dolomitic siltstone, sandy dolomite, and mudstone, and appears as isolated thin layers on the plane. The special type is mainly composed of mudstone and felsic siltstone, and mudstone, and turns up as lenses of different sizes on the plane.

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Microscale comprehensive evaluation of continental shale oil recoverability

Cited by 37 publications

References 18 publications

Molecular modeling on Gulong shale oil and wettability of reservoir matrix

Molecular modeling on Gulong shale oil and wettability of reservoir matrix

Mechanism of Forming Low Resistivity in Shale Reservoirs

Lithofacies Architecture and Distribution Patterns of Lacustrine Mixed Fine-Grained Rocks —a Case Study of Permian Lucaogou Formation in Jimsar Sag, NW China

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