A modified embedded discrete-fracture model to study oil-water two-phase heat and mass transfer in the complex fracture network

The embedded discrete fracture model (EDFM), among different flow simulation models, achieves a good balance between efficiency and accuracy. In the EDFM, micro-scale fractures that cannot be characterized individually need to be homogenized into the matrix, which may bring anisotropy into the matrix. However, the simplified matrix–fracture fluid exchange assumption makes it difficult for EDFM to address the anisotropic flow. In this paper, an integrally embedded discrete fracture model (iEDFM) suitable for anisotropic formations is proposed. Structured mesh is employed for the anisotropic matrix, and the fracture element, which consists of a group of connected fractures, is integrally embedded in the matrix grid. An analytic pressure distribution is derived for the point source in anisotropic formation expressed by permeability tensor, and applied to the matrix–fracture transmissibility calculation. Two case studies were conducted and compared with the analytic solution or fine grid result to demonstrate the advantage and applicability of iEDFM to address anisotropic formation. In addition, a two-phase flow example with a reported dataset was studied to analyze the effect of the matrix anisotropy on the simulation result, which also showed the feasibility of iEDFM to address anisotropic formation with complex fracture networks.

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The embedded discrete fracture model for two-phase flow involving the capillary pressure discontinuities in low-permeability reservoir

Journal of Physics Conference Series ◽

10.1088/1742-6596/1549/4/042017 ◽

2020 ◽

Vol 1549 ◽

pp. 042017

Author(s):

Zhanke Li ◽

Weidong Cao ◽

Zhifeng Liu ◽

Min Wang ◽

Jinbiao Yu ◽

...

Keyword(s):

Capillary Pressure ◽

Two Phase Flow ◽

Fracture Model ◽

Low Permeability ◽

Phase Flow ◽

Two Phase ◽

Discrete Fracture Model ◽

Low Permeability Reservoir ◽

Discrete Fracture

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A Discrete Fracture Modeling Approach for Analysis of Coalbed Methane and Water Flow in a Fractured Coal Reservoir

Geofluids ◽

10.1155/2020/8845348 ◽

2020 ◽

Vol 2020 ◽

pp. 1-15

Author(s):

Tianran Ma ◽

Hao Xu ◽

Chaobin Guo ◽

Xuehai Fu ◽

Weiqun Liu ◽

...

Keyword(s):

Water Flow ◽

Coalbed Methane ◽

Fluid Transport ◽

Fracture Model ◽

Phase Flow ◽

Two Phase ◽

Discrete Fracture Model ◽

Discrete Fracture ◽

Fractured Coal ◽

Cbm Production

As a complex two-phase flow in naturally fractured coal formations, the prediction and analysis of CBM production remain challenging. This study presents a discrete fracture approach to modeling coalbed methane (CBM) and water flow in fractured coal reservoirs, particularly the influence of fracture orientation, fracture density, gravity, and fracture skeleton on fluid transport. The discrete fracture model is first verified by two water-flooding cases with multi- and single-fracture configurations. The verified model is then used to simulate CBM production from a discrete fractured reservoir using four different fracture patterns. The results indicate that fluid behavior is significantly affected by orientation, density, and fracture connectivity. Finally, several cases are performed to investigate the influence of gravity and fracture skeleton. The simulation results show that gas migrates upwards to the top reservoir during fluid extraction owing to buoyancy and the connected fracture skeleton plays a dominant role in fluid transport and methane production efficiency. Overall, the developed discrete fracture model provides a powerful tool to study two-phase flow in fractured coal reservoirs.

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