Shale gas production from reservoirs with hierarchical multiscale structural heterogeneities

Tian, Jianwei; Liu, Jishan; Elsworth, Derek; Leong, Yee-Kwong; Li, Wai; Zeng, Jie

doi:10.1016/j.petrol.2021.109380

Cited by 19 publications

(21 citation statements)

References 53 publications

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“…Shale geomechanical deformation and fluid flow processes have been defined by eqs and , respectively. The interactions of these two processes can be linked through shale porosity and permeability models: − , ϕ ϕ 0 = exp false{ prefix− c normalp [ false( σ − σ 0 false) − false( p − p 0 false) ] + ( f − 1 ) normalΔ ε normals normalb false} k ap k in 0 = exp false{ prefix− 3 c normalp [ false( σ̅ − σ̅ 0 false) − false( p − p 0 false) ] + 3 ( f − 1 ) normalΔ ε normals normalb false} ( 1 + 2 2 c k B T π …”

Section: Challenges and Perspectivesmentioning

confidence: 99%

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A Review of Swelling Effect on Shale Permeability: Assessments and Perspectives

et al. 2023

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The significant effect of gas sorption induced swelling on shale permeability has been observed through laboratory measurements and explained through permeability models over the past decades. However, there are lab observations that cannot be explained by these models. This knowledge gap prompts this review. Our goal is to form perspectives on how to resolve this gap through assessing the role of swelling on shale permeability. This goal is achieved through the following three steps: (1) collection of experimental shale permeability data measured under both constant effective stress and constant confining pressure conditions; (2) collection and classification of shale permeability models under the influence of gas sorption induced swelling strains; (3) assessments of co-relations between shale permeability data and permeability models. On the basis of all assessments, we conclude that the discrepancies between model predictions and laboratory measurements depend on the relation between bulk and pore swelling strains, pore size scales, and consistencies of strain treatments in the experiments and models. Models assuming that bulk swelling strain is different from pore swelling strain can better explain lab observations than those assuming that they are the same. When the pore size transitions from the micron-scale to the nano-scale, the effect of swelling on shale permeability gradually diminishes. The inconsistencies between how swelling strains are measured in the lab and treated in the models are common in the literatures and affect the discrepancies between model predictions and lab observations. On the basis of these assessments, we form our perspectives: (1) transformation between bulk and pore swelling strains should be characterized and incorporated both for experiments and in permeability models; (2) shale multiscale pore structural characteristics should be characterized when assessing the swelling effect on shale permeability; (3) the time-dependent nature of swelling strain and permeability evolution should be incorporated into future experiments and permeability models.

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Section: Challenges and Perspectivesmentioning

confidence: 99%

Section: Challenges and Perspectivesmentioning

confidence: 99%

A Review of Swelling Effect on Shale Permeability: Assessments and Perspectives

et al. 2023

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Section: Storage and Transport Mechanism Of Gas In Shale Reservoirsmentioning

confidence: 99%

“…In Figure 14d, the pore-scale diameter (PSD) of the kerogen and inorganic matrix is shown alongside the natural fractures and hydraulic fractures, which elaborates the interconnection between the different domains of the reservoir. According to Tian et al, 117 the pore diameters of the kerogen are in the nanoscale, which is of the same order of magnitude as the mean free path of the gas molecule; meanwhile, the heterogeneous PSD of the matrix and natural fractures affects the transport of gas and overall production. Therefore, the triplecontinuum model should cater to the local kerogen heterogeneities by adopting the fractal theory, which considers the tortuous channels of the kerogen in the inorganic matrix.…”

Section: Multiscale Storage and Transport Of Gas In Shalementioning

confidence: 99%

Hydraulic Fracturing and Enhanced Recovery in Shale Reservoirs: Theoretical Analysis to Engineering Applications

et al. 2023

Energy Fuels

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Shale reservoirs are extensively exploited using hydraulic fracturing, which forms multiple cracks that connect with the existing natural fractures to create a continuous path for the gas stored in the kerogen to flow to the production well. Apart from the tedious nature of hydraulic fracturing, the mechanism of the storage and flow of gas is equally complex since multiple phases and scales are involved. An accurate understanding of hydraulic fracturing coupled with a strategy of analyzing the flow and overall recovery of gas is paramount to ensure efficient exploitation. In this work, a comprehensive review of the recent strategies used in analyzing the hydraulic fracturing, storage, flow, and recovery of gas is presented. To begin with, the experimental, analytical, and numerical approaches pertinent to hydraulic fracturing are deeply explored. Additionally, the flow of gas through the newly opened channels is accounted for by using a quadruple-domain approach where the mechanisms of flow in shale reservoirs at the nanoscale, microscale, mesoscale, and macroscale are considered. Furthermore, a strategy to capture the multiple phases, including gas, oil, and water, and recover both carbon dioxide and methane is explored through thermal and enhanced gas recovery approaches. This review provides a baseline for understanding how the hydraulic fracture evolves and propagates to create new channels that contribute to the flow of gas, how the gas flows through the created channels across the many scales of the shale reservoir, and how to improve recovery from shale reservoirs.

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“…Many theoretical models have been established to reveal the influences of various factors, such as inherent structural heterogeneity and geo-stress, on CBM production. − Effective stress and swelling stress play pivotal roles in affecting the coal permeability during CBM production . Accordingly, fully coupled hydro-mechanical models have been applied to predict the gas and water production, which demonstrated the close relationship between effective stress and CBM production. , Apart from the absolute and relative permeabilities, the residual water saturation also varies with effective stress .…”

Section: Introductionmentioning

confidence: 99%

Linking Fractal Theory to a Fully Coupled Coal Deformation and Two-Phase Flow Multiphysics: The Role of Fractal Dimensions

et al. 2022

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The fractal nature of coal pore sizes affects both coal absolute and relative permeabilities. Previous studies have demonstrated the significant role of coal absolute permeability models in evaluating coal gas extraction, but the role of relative permeability models remains unknown. In this study, the fractal theory was employed to derive new relative permeability models. These new models are verified against the relative permeability data available in the literature. The verified permeability models are used to fully couple coal deformation and two-phase flow during coalbed methane extraction. The degenerated fully coupled model was verified against data obtained from another commercial simulator. The verified model was applied to conduct a series of sensitivity studies of gas production to fractal dimensions. The results show that the larger fractal dimension suggests higher residual water saturation, which compromises the relative permeability correspondingly. The larger fractal parameter facilitates gas recovery although the capillary pressure is enhanced accordingly. Absolute permeability rebounds with the decline of pore pressure, indicating that the dominant factor for gas production transforms from relative permeability in the early stage to absolute permeability in the later stage.

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Shale gas production from reservoirs with hierarchical multiscale structural heterogeneities

Cited by 19 publications

References 53 publications

A Review of Swelling Effect on Shale Permeability: Assessments and Perspectives

A Review of Swelling Effect on Shale Permeability: Assessments and Perspectives

Hydraulic Fracturing and Enhanced Recovery in Shale Reservoirs: Theoretical Analysis to Engineering Applications

Linking Fractal Theory to a Fully Coupled Coal Deformation and Two-Phase Flow Multiphysics: The Role of Fractal Dimensions

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