Fluid Flow Characterization Framework for Naturally Fractured Reservoirs Using Small-Scale Fully Explicit Models

Wong, Daniel Lorng Yon; Doster, Florian; Geiger, Sebastian; Francot, Eddie; Gouth, Francois Michel

doi:10.1007/s11242-020-01451-8

Cited by 12 publications

(4 citation statements)

References 55 publications

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“…In modern reservoir simulation, which includes highly implicit time approximation using finite-volume discretization on unstructured grids, the DFM methodology has been introduced by Karimi-Fard et al (2004). The DFM approach is often preferred in detailed geological studies due to its accuracy (Berre et al, 2019;Flemisch et al, 2018;Moinfar et al, 2011;Wong et al, 2020). DFM models typically require a high meshing accuracy to resolve the fracture networks' complex geometry, thereby drastically increasing the computational complexity and rendering them unusable for uncertainty quantification purposes (Jung et al, 2013;Nejadi et al, 2017;Spooner et al, 2021).…”

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confidence: 99%

An Advanced Discrete Fracture Methodology for Fast, Robust, and Accurate Simulation of Energy Production From Complex Fracture Networks

Hoop

Voskov

Bertotti

et al. 2022

Water Resources Research

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Fracture networks are abundant in subsurface applications (e.g., geothermal energy production, CO2 sequestration). Fractured reservoirs often have a very complex structure, making modeling flow and transport in such networks slow and unstable. Consequently, this limits our ability to perform uncertainty quantification and increases development costs and environmental risks. This study provides an advanced methodology for simulation based on Discrete Fracture Model approach. The preprocessing framework results in a fully conformal, uniformly distributed grid for realistic 2D fracture networks at a required level of precision. The simplified geometry and topology of the resulting network are compared with input (i.e., unchanged) data to evaluate the preprocessing influence. The resulting mesh‐related parameters, such as volume distributions and orthogonality of control volume connections, are analyzed. Furthermore, changes in fluid‐flow response related to preprocessing are evaluated using a high‐enthalpy two‐phase flow geothermal simulator. The simplified topology directly improves meshing results and, consequently, the accuracy and efficiency of numerical simulation. The main novelty of this work is the introduction of an automatic preprocessing framework allowing us to simplify the fracture network down to required level of complexity and addition of a fracture aperture correction capable of handling heterogeneous aperture distributions, low connectivity fracture networks, and sealing fractures. The graph‐based framework is fully open‐source and explicitly resolves small‐angle intersections within the fracture network. A rigorous analysis of changes in the static and dynamic impact of the preprocessing algorithm demonstrates that explicit fracture representation can be computationally efficient, enabling their use in large‐scale uncertainty quantification studies.

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mentioning

confidence: 99%

An Advanced Discrete Fracture Methodology for Fast, Robust, and Accurate Simulation of Energy Production From Complex Fracture Networks

Hoop

Voskov

Bertotti

et al. 2022

Water Resources Research

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“…As can be seen, the major fractures' aperture and permeability were constant in all categories. The fracture permeability was selected to be higher than the matrix for all the cases to avoid any numerical issues, as recommended by Wong et al [29] with a similar embedded district fracture model (EDFM).…”

Section: R M12 =mentioning

confidence: 99%

Assessing the Influence of Fracture Networks on Gas-Based Enhanced Oil Recovery Methods

Kharrat,

Alalim,

Ott

2023

Energies

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Numerous reservoirs that play a significant role in worldwide petroleum production and reserves contain fractures. Typically, the fractures must form a connected network for a reservoir to be classified as naturally fractured. Characterizing the reservoir with a focus on its fracture network is crucial for modeling and predicting production performance. To simplify the solution, dual-continuum modeling techniques are commonly employed. However, to use continuum-scale approaches, properties such as the average aperture, permeability, and matrix fracture interaction parameters must be assigned, making it necessary to improve the fracture depiction and modeling methods. This study investigated a fractured reservoir with a low matrix permeability and a well-connected fracture network. The focus was on the impact of the hierarchical fracture network on the production performance of gas-based enhanced oil recovery methods. The discrete fracture network (DFN) model was utilized to create comprehensive two-dimensional models for three processes: gas injection (GI), water alternating gas (WAG), and foam-assisted water alternating gas (FAWAG). Moreover, dimensionless numbers were employed to establish connections between properties across the entire fracture hierarchy, spanning from minor to major fractures and encompassing the fracture intensity. The results indicate that the FAWAG process was more sensitive to fracture types and networks than the WAG and GI processes. Hence, the sensitivity of the individual EOR method to the fracture network requires a respective depth of description of the fracture network. However, other factors, such as reservoir fluid properties and fracture properties, might influence the recovery when the minor fracture networks are excluded. This study determined that among the enhanced oil recovery (EOR) techniques examined, the significance of the hierarchical depth of fracture networks diminished as the ratio of major (primary fracture) aperture to the aperture of medium and minor fractures increased. Additionally, the impact of the assisted-gravity drainage method was greater with increased reservoir height; however, as the intensity ratio increased, the relative importance of the medium and minor fracture networks decreased.

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“…The presence of natural fractures plays an important role in the ultimate recovery and has a great effect on the reservoir performance; however, it is computationally expensive (if not technically infeasible) to take into account all fractures or fracture networks in standard reservoir simulators. Therefore, many studies have been published in the literature to propose different techniques on how to represent the natural fractures in reservoir simulators [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18][19][20]. These studies can be divided into three groups based on how they account for the presence of natural fractures: 1-the dual continuum approach, 2-the discrete fracture network, and 3-the hybrid approach.…”

Section: Introductionmentioning

confidence: 99%

A Coupled Poro-Elastic Fluid Flow Simulator for Naturally Fractured Reservoirs

Abdel Azim,

Alatefi,

Alkouh

2023

Energies

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Naturally fractured reservoirs are characterized by their complex nature due to the existence of natural fractures and fissures within the rock formations. These fractures can significantly impact the flow of fluids within the reservoir, making it difficult to predict and manage production. Therefore, efficient production from such reservoirs requires a deep understanding of the flow behavior via the integration of various geological, geophysical, and engineering data. Additionally, advanced simulation models can be used to predict reservoir behavior under different production scenarios and aid in decision making and effective management. Accordingly, this study presents a robust mathematical two-phase fluid flow model (FRACSIM) for the simulation of the flow behavior of naturally fractured reservoirs in a 3D space. The mathematical model is based on the finite element technique and implemented using the FORTRAN language within a poro-elastic framework. Fractures are represented by triangle elements, while tetrahedral elements represent the matrix. To optimize computational time, short to medium-length fractures adopt the permeability tensor approach, while large fractures are discretized explicitly. The governing equations for poro-elasticity are discretized in both space and time using a standard Galerkin-based finite element approach. The stability of the saturation equation solution is ensured via the application of the Galerkin discretization method. The 3D fracture model has been verified against Eclipse 100, a commercial software, via a well-test case study of a fractured basement reservoir to ensure its effectiveness. Additionally, the FRACSIM software successfully simulated a laboratory glass bead drainage test for two intersected fractures and accurately captured the flow pattern and cumulative production results. Furthermore, a sensitivity study of water injection using an inverted five-spot technique was tested on FRACSIM to assess the productivity of drilled wells in complex fractured reservoirs. The results indicate that FRACSIM can accurately predict flow behavior and subsequently be utilized to evaluate production performance in naturally fractured reservoirs.

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Fluid Flow Characterization Framework for Naturally Fractured Reservoirs Using Small-Scale Fully Explicit Models

Cited by 12 publications

References 55 publications

An Advanced Discrete Fracture Methodology for Fast, Robust, and Accurate Simulation of Energy Production From Complex Fracture Networks

An Advanced Discrete Fracture Methodology for Fast, Robust, and Accurate Simulation of Energy Production From Complex Fracture Networks

Assessing the Influence of Fracture Networks on Gas-Based Enhanced Oil Recovery Methods

A Coupled Poro-Elastic Fluid Flow Simulator for Naturally Fractured Reservoirs

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