Development of an embedded discrete fracture model for 2D and 3D unstructured grids using an element-based finite volume method

Xu, Yifei; Lima, Ivan Costa; Marcondes, Francisco; Sepehrnoori, Kamy

doi:10.1016/j.petrol.2020.107725

Cited by 16 publications

(2 citation statements)

References 45 publications

(76 reference statements)

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“…The finite volume method is based on irregular grid simulation. Using this, Xu et al [20] introduced an element-based finite volume method to a threedimensional embedded discrete fracture model and improved the flexibility of fracture patterns. Special discrete methods such as the discontinuous finite element method can solve many difficult problems, such as highly permeable anisotropic reservoirs.…”

Section: Introductionmentioning

confidence: 99%

Numerical Investigation of Multistage Fractured Horizontal Wells considering Multiphase Flow and Geomechanical Effects

Liu

2021

Geofluids

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Hydraulic fracturing is a key technology in unconventional reservoir production, yet many simulators only consider the single-phase flow of shale gas, ignoring the two-phase flow process caused by the retained fracturing fluid in the early stage of production. In this study, a three-dimensional fluid–gas–solid coupling reservoir model is proposed, and the governing equations which involve the early injection water phenomenon and stress-sensitive characteristics of shale gas reservoirs are established. The finite element–finite difference method was used for discretisation of stress and strain equations and the equations of flow balances. Further, a sensitivity analysis was conducted to analyse fracture deformation changes in the production. Fracture characteristics under different rock mechanics coefficients were simulated, and the influence of rock mechanics parameters on productivity was further characterised. The stimulated reservoir volume zone permeability could determine the retrofitting effect, the permeability increased from 0.02 to 0.1 mD, and cumulative gas production increased from 18.08 to 26.42 million m3, thus showing an increase of 8.34 million m3, or 46%. The effect of Young’s modulus on the yield was smaller than Poisson’s ratio and the width and length of the fractures. Production was most sensitive to the length of the fractures. The length of the fracture increased from 200 to 400 m, and the cumulative gas production increased from 26.44 to 38.34 million m3, showing an increase of 11.9 million m3, or 45%. This study deepens the understanding of the production process of shale gas reservoirs and has significance for the fluid–gas–solid coupling of shale gas reservoirs.

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Section: Introductionmentioning

confidence: 99%

Numerical Investigation of Multistage Fractured Horizontal Wells considering Multiphase Flow and Geomechanical Effects

Liu

2021

Geofluids

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“…In their work, a vertex-based geometric algorithm is developed to handle discretization errors caused by local domain resolution, although the method is not optimized to simulate a fluid in transient state crossing a large size matrix with low permeability. Xu et al (2020) extended the EDFM for unstructured grid using element-based finite volume method (EbFVM), a method based on finite elements and the finite volume method that enhances non-matching discretization and maintains local mass conservation. The method was adopted 1.3 Objectives to treat fracture networks in 2D and 3D hydraulic problems.…”

Section: Discrete Fracture Modelsmentioning

confidence: 99%

An embedded discrete fracture model based on the use of coupling finite elements for modeling fluid flow in naturally fractured porous media.

Borges¹

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Petroleum is a natural occurrence of hydrocarbons and inorganic impurities, usually presented in a liquid or gas phase in a system. Some reservoirs rock which stores the hydrocarbon can be separated between two domains: the porous medium and the fracture network which may creates preferential channels that change the equivalent permeability of the medium. Many numerical models have been proposed to simulate fluid flow in naturally fractured reservoirs, however, the representation of the complex geometric characteristics of the fracture network is still an issue nowadays. In this sense, this work proposes an embedded discrete fracture model based on the use of coupling finite elements (CFEs) for modeling fluid flow in naturally fractured porous media. The proposed model is able to couple the initially independent non-matching and overlapping meshes from the fractures and rock matrix via CFEs to enforce the continuity of the pressure field between the meshes through a penalty parameter. The main advantage of the use of this approach is that the implementation of CFEs does not require additional degrees of freedom or special integration procedures for coupling the non-matching meshes. Three sets of 2D numerical examples are performed to validate the proposed approach for modeling the steady-state flow in fractured porous medium. The first set of numerical examples focused on the influence of the natural fractures position and the penalty parameter magnitude. In the second set of examples, a study of mesh refinement is performed considering fracture intersections in order to assess the capability of the proposed model to account for the contribution of each discontinuity to the pressure field. The last set of numerical examples presents the simulation of a complex naturally fractured porous medium with vug pore spaces. In conclusion with the results obtained: (i) the coarse meshes presents good results in comparison with refined meshes; (ii) a ratio of porous media and fracture elements between 1 and 2 is acceptable for better results; and (iii) and an specific value of the penalty parameter is applied to predict better behavior of fluid flow in porous medium. Furthermore, the results are in good agreement with reference solutions (the numerical results obtained in iv previous studies) and the proposed approach demonstrated to be able to capture the main phenomena associated with the fluid transport in fractured porous media.

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Coupled hydro-mechanical two-phase flow model in fractured porous medium with the combined finite-discrete element method

Sun,

Tang,

Aboayanah

et al. 2024

Engineering with Computers

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Development of an embedded discrete fracture model for 2D and 3D unstructured grids using an element-based finite volume method

Cited by 16 publications

References 45 publications

Numerical Investigation of Multistage Fractured Horizontal Wells considering Multiphase Flow and Geomechanical Effects

Numerical Investigation of Multistage Fractured Horizontal Wells considering Multiphase Flow and Geomechanical Effects

An embedded discrete fracture model based on the use of coupling finite elements for modeling fluid flow in naturally fractured porous media.

Coupled hydro-mechanical two-phase flow model in fractured porous medium with the combined finite-discrete element method

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