Development of a FEM reservoir model equipped with an effective permeability tensor and its application to naturally fractured reservoirs

Y. C. Park, Won Mo Sung, S. J. Kim

Research output: Contribution to specialist publicationArticle

9 Citations (Scopus)

Abstract

The numerical simulation of naturally fractured reservoirs is commonly based on the continuum dual-porosity concept. However, the model needs to assume that the fractures form very regular patterns, different from field observations. In order to overcome this problem, we proposed a method that can consider the characteristics of the real fracture system and developed a two-phase transient finite element method (FEM) (TENFEM) model able to implement an effective permeability tensor. The permeability tensors were estimated by using a single-phase, steady-state FEM (EPC) model also coded in this work, where Darcy's law in matrix and cubic law in fracture were adopted for considering the flow characteristics in the discrete fracture network (DFN) approach. The developed models were applied to the paludat sand reservoir of a multiwell experiment (MWX) site to demonstrate validity and applicability of the models. The estimated average permeability in the MWX is almost identical compared to the results of the well test analysis. Then the numerical simulation with the TENFEM model was performed by using the transient pressure recorded from a gas well test on the MWX #1. From the results of bottom hole pressure and pressure distribution within the system, it was noted that the model with effective permeabilities generated almost identical results against the DFN model in the aspects of the behavior and the direction of fluid propagation with pressure decline, and therefore the proposed model is considered to be more efficient in terms of the computation time as well as the required storage capacity. Also from the upscaling study, it was shown that even with fewer numbers of grid blocks the developed model could effectively describe the directional flow caused by the fracture characteristics such as orientation and density of the fracture.

Original languageEnglish
Pages531-542
Number of pages12
Volume24
No6
Specialist publicationEnergy Sources
DOIs
StatePublished - 2002 Jun 1

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Tensors
Finite element method
Bottom hole pressure
Experiments
Computer simulation
Pressure distribution
Sand
Porosity
Gases
Fluids

Keywords

  • Naturally fractured reservoir
  • Permeability tensor
  • Transient FEM model
  • Upscaling

Cite this

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abstract = "The numerical simulation of naturally fractured reservoirs is commonly based on the continuum dual-porosity concept. However, the model needs to assume that the fractures form very regular patterns, different from field observations. In order to overcome this problem, we proposed a method that can consider the characteristics of the real fracture system and developed a two-phase transient finite element method (FEM) (TENFEM) model able to implement an effective permeability tensor. The permeability tensors were estimated by using a single-phase, steady-state FEM (EPC) model also coded in this work, where Darcy's law in matrix and cubic law in fracture were adopted for considering the flow characteristics in the discrete fracture network (DFN) approach. The developed models were applied to the paludat sand reservoir of a multiwell experiment (MWX) site to demonstrate validity and applicability of the models. The estimated average permeability in the MWX is almost identical compared to the results of the well test analysis. Then the numerical simulation with the TENFEM model was performed by using the transient pressure recorded from a gas well test on the MWX #1. From the results of bottom hole pressure and pressure distribution within the system, it was noted that the model with effective permeabilities generated almost identical results against the DFN model in the aspects of the behavior and the direction of fluid propagation with pressure decline, and therefore the proposed model is considered to be more efficient in terms of the computation time as well as the required storage capacity. Also from the upscaling study, it was shown that even with fewer numbers of grid blocks the developed model could effectively describe the directional flow caused by the fracture characteristics such as orientation and density of the fracture.",
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Development of a FEM reservoir model equipped with an effective permeability tensor and its application to naturally fractured reservoirs. / Park, Y. C.; Sung, Won Mo; Kim, S. J.

In: Energy Sources, Vol. 24, No. 6, 01.06.2002, p. 531-542.

Research output: Contribution to specialist publicationArticle

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