Comparison between a Finite-Volume Mesh and a Connectivity List-Based Discretization for High Resolution Discrete Fracture Representations.

Sarah Vitel and B. Gong and M. Karimi-Fard and Guillaume Caumon. ( 2007 )
in: Proc. 27th Gocad Meeting, Nancy

Abstract

Construction of fractured reservoir models for flow simulation requires the development of accurate and efficient methods, able to handle numerous fractures and very complex 3D geometries while informing a flow simulator. Currently, two main approaches have been developed. The first one uses a pipe network to efficiently describe the fracture network, but is limited to model flow only within fractures, and therefore will not properly handle a few connected fracture networks, and matrix with non-negligible permeability. The second approach builds a fully unstructured mesh integrating the fractures, which accurately discretizes the whole fractured medium, but requires advanced griding techniques that are computationally demanding. Alternative approaches have thus been proposed in the literature, in order to improve the performance of the discretization. Among them, a hybrid technique uses a pipe network to jointly discretize discrete fracture network and a corner-point grid representing the matrix [Vitel, 2006]. Thus, flow can occur both in fractures and matrix, while the flexibility and efficiency of the pipe network allow to model large 3D complex reservoirs with thousands of fractures, in only a few minutes on a regular workstation. However, for efficiency purpose, this technique introduces a few approximations in the way matrix-fracture connections are created. This article presents a comparison between the finite-volume discretization technique proposed by Karimi-Fard et al. [2004] and the hybrid pipe network method proposed by Vitel [2006]. Since the first method is free from the pipe network approximations, this comparison allows to assess their impact on the flow simulation results. Different scenarii of flow simulations have been run, and all results show very good agreement between both models, while the mesh construction greatly gains from using the pipe network.

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    BibTeX Reference

    @INPROCEEDINGS{P401_Vitel,
        author = { Vitel, Sarah and Gong, B. and Karimi-Fard, M. and Caumon, Guillaume },
         title = { Comparison between a Finite-Volume Mesh and a Connectivity List-Based Discretization for High Resolution Discrete Fracture Representations. },
     booktitle = { Proc. 27th Gocad Meeting, Nancy },
          year = { 2007 },
      abstract = { Construction of fractured reservoir models for flow simulation requires the development of accurate
    and efficient methods, able to handle numerous fractures and very complex 3D geometries while
    informing a flow simulator. Currently, two main approaches have been developed. The first one uses
    a pipe network to efficiently describe the fracture network, but is limited to model flow only within
    fractures, and therefore will not properly handle a few connected fracture networks, and matrix with
    non-negligible permeability. The second approach builds a fully unstructured mesh integrating the
    fractures, which accurately discretizes the whole fractured medium, but requires advanced griding
    techniques that are computationally demanding. Alternative approaches have thus been proposed in
    the literature, in order to improve the performance of the discretization. Among them, a hybrid
    technique uses a pipe network to jointly discretize discrete fracture network and a corner-point grid
    representing the matrix [Vitel, 2006]. Thus, flow can occur both in fractures and matrix, while
    the flexibility and efficiency of the pipe network allow to model large 3D complex reservoirs with
    thousands of fractures, in only a few minutes on a regular workstation. However, for efficiency
    purpose, this technique introduces a few approximations in the way matrix-fracture connections are
    created.
    This article presents a comparison between the finite-volume discretization technique proposed
    by Karimi-Fard et al. [2004] and the hybrid pipe network method proposed by Vitel [2006]. Since
    the first method is free from the pipe network approximations, this comparison allows to assess their
    impact on the flow simulation results. Different scenarii of flow simulations have been run, and all
    results show very good agreement between both models, while the mesh construction greatly gains
    from using the pipe network. }
    }