Embedded Discrete Fracture Modeling as a Method to Upscale Permeability for Fractured Reservoirs

Dong, Zhenzhen; Li, Weirong; Lei, Gang; Wang, Huijie; Cai, Wenjun

doi:10.3390/en12050812

Cited by 19 publications

(8 citation statements)

References 24 publications

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“…This fluid velocity increase inside the natural fractures (Figure 2(d)) is the primary reason for preferential flow paths and flow channeling due to fracture networks [49][50][51][52]. Multiple tracer transport studies on core samples of different length scales have shown that flow inside a fractured reser-voir is highly heterogeneous [52][53][54][55]. Natural fractures may also result in fracture/well communication; thus, they need to be adequately accounted for while designing the infill wells and hydraulic fractures [1,2].…”

Section: Determination Of Permeability Contrast With Matrix Andmentioning

confidence: 99%

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Comparison of Flow Solutions for Naturally Fractured Reservoirs Using Complex Analysis Methods (CAM) and Embedded Discrete Fracture Models (EDFM): Fundamental Design Differences and Improved Scaling Method

Khanal

Weijermars

2020

Geofluids

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The present study compares flow paths in reservoirs with natural fractures, solved with Complex Analysis Methods (CAM), to those solved with Embedded Discrete Fracture Models (EDFM). One aim is to define scaling rules for the strength (flux) of the discrete natural fractures used in CAM models, which was previously theoretically defined based on the expected flow distortion. A major hurdle for quantitative benchmarks of CAM with EDFM results is that each of the two methods accounts for natural fractures with different assumptions and input parameters. For example, EDFM scales the permeability of the natural fractures based on a cubic equation, while CAM uses a flux strength. The results from CAM and EDFM are used to scale the flux strength of the natural fractures and improve the equivalent permeability contrast estimation for CAM. The permeability contrast for CAM is calculated from the ratio of the enhanced velocity inside natural fractures to the unperturbed matrix fluid velocity. A significant advantage of flow and pressure models based on CAM is the high resolution without complex gridding. Particle tracking results are presented for fractures with different hydraulic conductivity ranging from highly permeable to impervious.

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Section: Determination Of Permeability Contrast With Matrix Andmentioning

confidence: 99%

“…Thus, EDFM does not require a conforming mesh for the discrete fractures, which reduces the gridding complexity. Several authors have recently presented EDFM as a promising alternative to DFN and other upscaled single/multicontinuum models [25,52,53].…”

Section: Scaling Natural Fracture Strength To Permeability Usingmentioning

confidence: 99%

Comparison of Flow Solutions for Naturally Fractured Reservoirs Using Complex Analysis Methods (CAM) and Embedded Discrete Fracture Models (EDFM): Fundamental Design Differences and Improved Scaling Method

Khanal

Weijermars

2020

Geofluids

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“…We will consider two solutions of incompressible (both solid skeleton and fluid) single phase flow problems. Note here we must deal with fissures explicitly either through DFM combined with local grid refinement (LGR) [26,58,60] or EDFM [39], but the good thing is that we just need to solve a single PDE, i.e., ∇ • q = 0. Both solutions will use linear pressure gradient boundary conditions [40].…”

Section: Computing Equivalent Permeability Kmentioning

confidence: 99%

Fluid flow through anisotropic and deformable double porosity media with ultra-low matrix permeability: A continuum framework

Zhang,

Yan,

Shao

2020

Preprint

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Fractured porous media or double porosity media are common in nature. At the same time, accurate modeling remains a significant challenge due to bi-modal pore size distribution, anisotropy, multi-field coupling and various flow patterns. The purpose of this study is to formulate a comprehensive coupled flow and geomechanics model of anisotropic and deformable double porosity media with ultra-low matrix permeability. Fluid in fissures is modeled with the generalized Darcy's law with an equivalent permeability upscaled from the detailed geological characterizations while the liquid in much less permeable matrix follows a low velocity non-Darcy flow characterized by threshold values and non-linearity, and fluid mass transfer is dependent on the shape factor, phase pressure difference, and interface permeability. The geomechanics relies on a thermodynamically consistent effective stress derived from the energy balance equation, and it is modeled following poroelastic theory. Scaling analysis is performed to drop negligible force density terms under reasonable parameters' ranges which also guarantee no violation of entropy inequality. The discussion revolves around generic double porosity media. Numerical simulation of the initial boundary value problem reveals the capability of this framework to capture the crucial role of coupling, anisotropy and ultra-low matrix permeability in dictating the pressure and displacement fields.

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“…In recent years, the EDFM is very popular due to its high compatibility with existing reservoir simulators (Yu et al, 2018;Dong et al, 2019;Zhang et al, 2020;Zhu et al, 2020). This method can smoothly embed fractures in the reservoir without impacting the existing grid.…”

Section: Introductionmentioning

confidence: 99%

A Novel model for simulating the integration process of hydraulic fracturing, shut-in period, and well production

Luo

Chen³

et al. 2022

Front. Energy Res.

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Distributions of pore pressure and water saturation in matrix around fractures after hydraulic fracturing and shut-in period will impact the shale gas well production significantly. However, the influences of hydraulic fracturing and shut-in period on pore pressure and water saturation are not considered in the classical reservoir simulations. In this work, the embedded discrete fracture model (EDFM), which is convenient to be coupled with an existing reservoir simulator with high computational efficiency, was employed to simulate the hydraulic fracture propagation coupled with matrix flow. Then, we developed a model for simulating the integration process of hydraulic fracturing, shut-in period, and well production based on the dual media theory. Distributions of pore pressure and water saturation varying in different periods and the production decline of shale gas well were obtained through the integrated simulation model. The calculation result was validated by the field bottom hole pressure data of a shale gas well in Sichuan Province, China. Simulation results show that the variation of bottom hole pressure is not smooth during the fracture propagation process because the initiations of different fractures are not simultaneous. The fracturing fluid flow-back rate of shale gas well is much lower than that of conventional reservoirs. There is still a large amount of fracturing fluid retained in micro-fracture systems and matrix of shale after production. It is also found that the permeability of the micro-fracture system determines the drop rate of bottom hole pressure and the size of stimulated reservoir volume (SRV) determines the decrease amplitude of bottom hole pressure.

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Embedded Discrete Fracture Modeling as a Method to Upscale Permeability for Fractured Reservoirs

Cited by 19 publications

References 24 publications

Comparison of Flow Solutions for Naturally Fractured Reservoirs Using Complex Analysis Methods (CAM) and Embedded Discrete Fracture Models (EDFM): Fundamental Design Differences and Improved Scaling Method

Comparison of Flow Solutions for Naturally Fractured Reservoirs Using Complex Analysis Methods (CAM) and Embedded Discrete Fracture Models (EDFM): Fundamental Design Differences and Improved Scaling Method

Fluid flow through anisotropic and deformable double porosity media with ultra-low matrix permeability: A continuum framework

A Novel model for simulating the integration process of hydraulic fracturing, shut-in period, and well production

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