scholarly journals Stochastic modeling of flow and conservative transport in three-dimensional discrete fracture networks

2019 ◽  
Vol 23 (1) ◽  
pp. 19-34 ◽  
Author(s):  
I-Hsien Lee ◽  
Chuen-Fa Ni ◽  
Fang-Pang Lin ◽  
Chi-Ping Lin ◽  
Chien-Chung Ke
Keyword(s):  
Transport Model ◽  
Three Dimensional ◽  
Element Model ◽  
Breakthrough Curves ◽  
Fracture Networks ◽  
Transition Zones ◽  
Darcy Velocity ◽  
Discrete Fracture Networks ◽  
Discrete Fracture ◽  
Sampling Volume

Abstract. This study presents the stochastic Monte Carlo simulation (MCS) to assess the uncertainty of flow and conservative transport in 3-D discrete fracture networks (DFNs). The MCS modeling workflow involves a number of developed modules, including a DFN generator, a DFN mesh generator, and a finite element model for solving steady-state flow and conservative transport in 3-D DFN realizations. The verification of the transport model relies on the comparison of transport solutions obtained from HYDROGEOCHEM model and an analytical model. Based on 500 DFN realizations in the MCS, the study assesses the effects of fracture intensities on the variation of equivalent hydraulic conductivity and the exhibited behaviors of concentration breakthrough curves (BTCs) in fractured networks. Results of the MCS show high variations in head and Darcy velocity near the specified head boundaries. There is no clear stationary region obtained for the head variance. However, the transition zones of nonstationarity for x-direction Darcy velocity is obvious, and the length of the transition zone is found to be close to the value of the mean fracture diameter for the DFN realizations. The MCS for DFN transport indicates that a small sampling volume in DFNs can lead to relatively high values of mean BTCs and BTC variations.

scholarly journals Stochastic modeling of flow and conservative transport in threedimensional discrete fracture networks

2018 ◽  
Author(s):  
I.-Hsien Lee ◽  
Chuen-Fa Ni ◽  
Fang-Pang Lin ◽  
Chi-Ping Lin ◽  
Chien-Chung Ke
Keyword(s):  
Transport Model ◽  
Element Model ◽  
Breakthrough Curves ◽  
Fracture Networks ◽  
Transition Zones ◽  
Darcy Velocity ◽  
Discrete Fracture Networks ◽  
Discrete Fracture ◽  
Sampling Volume ◽  
The Mean

Abstract. This study presents the stochastic Monte Carlo simulation (MCS) to assess the uncertainty of flow and conservative transport in 3D discrete fracture networks (DFNs). The MCS modeling workflow involves a number of developed modules, including a DFN generator, a DFN mesh generator, and a finite element model for solving steady-state flow and conservative transport in 3D DFN realizations. The verification of the transport model relies on the comparison of transport solutions obtained from HYDROGEOCHEM model and an analytical model. Based on 500 DFN realizations in the MCS, the study assesses the effects of fracture intensities on the variation of equivalent hydraulic conductivity and the exhibited behaviors of concentration breakthrough curves (BTCs) in fractured networks. Results of the MCS show high variations in head and Darcy velocity near the specified head boundaries. There is no clear stationary region obtained for the head variance. However, the transition zones of nonstationarity for x-direction Darcy velocity is obvious and the length of the transition zone is found to be close to the value of the mean fracture diameter for the DFN realizations. The MCS for DFN transport indicates that a small sampling volume in DFNs can lead to relatively high values of mean BTCs and BTC variations.

EFFECT OF FRACTAL FRACTURES ON PERMEABILITY IN THREE-DIMENSIONAL DIGITAL ROCKS

Fractals ◽  
2019 ◽  
Vol 27 (01) ◽  
pp. 1940015 ◽  
Author(s):  
WEIFENG LV ◽  
GUOLIANG YAN ◽  
YONGDONG LIU ◽  
XUEFENG LIU ◽  
DONGXING DU ◽  
...  
Keyword(s):  
Fractal Dimension ◽  
Fractal Theory ◽  
Fractured Reservoirs ◽  
Three Dimensional ◽  
Absolute Permeability ◽  
Fracture Aperture ◽  
Fracture Networks ◽  
Discrete Fracture Networks ◽  
Discrete Fracture ◽  
The Relationship

The fracture has great impact on the flow behavior in fractured reservoirs. Fracture traces are usually self-similar and scale-independent, which makes the fractal theory become a powerful tool to characterize fracture. To obtain three-dimensional (3D) digital rocks reflecting the properties of fractured reservoirs, we first generate discrete fracture networks by stochastic modeling based on the fractal theory. These fracture networks are then added to the existing digital rocks of rock matrixes. We combine two low-permeable cores as rock matrixes with a group of discrete fracture networks with fractal characteristics. Various types of fractured digital rocks are obtained by adjusting different fracture parameters. Pore network models are extracted from the 3D fractured digital rock. Then the permeability is predicted by Darcy law to investigate the impacts of fracture properties to the absolute permeability. The permeability of fractured rock is subject to exponential increases with fracture aperture. The relationship between the permeability and the fractal dimension of fracture centers is exponential, as well as the relationship between permeability and the fractal dimension of fracture lengths.

scholarly journals Identifying Backbones in Three-Dimensional Discrete Fracture Networks: A Bipartite Graph-Based Approach

2018 ◽  
Vol 16 (4) ◽  
pp. 1948-1968 ◽  
Author(s):  
Jeffrey D. Hyman ◽  
Aric Hagberg ◽  
Dave Osthus ◽  
Shriram Srinivasan ◽  
Hari Viswanathan ◽  
...  
Keyword(s):  
Bipartite Graph ◽  
Three Dimensional ◽  
Fracture Networks ◽  
Discrete Fracture Networks ◽  
Discrete Fracture

Fully Coupled Hydromechanical Simulation of Hydraulic Fracturing in Three-Dimensional Discrete Fracture Networks

2015 ◽  
Author(s):  
Mark W. McClure ◽  
Mohsen Babazadeh ◽  
Sogo Shiozawa ◽  
Jian Huang
Keyword(s):  
Hydraulic Fracturing ◽  
Hydraulic Fracture ◽  
Three Dimensional ◽  
Hydraulic Fractures ◽  
Fracture Aperture ◽  
Natural Fractures ◽  
Fracture Networks ◽  
Field Scale ◽  
Discrete Fracture Networks ◽  
Discrete Fracture

Abstract We developed a hydraulic fracturing simulator that implicitly couples fluid flow with the stresses induced by fracture deformation in large, complex, three-dimensional discrete fracture networks. The simulator can describe propagation of hydraulic fractures and opening and shear stimulation of natural fractures. Fracture elements can open or slide, depending on their stress state, fluid pressure, and mechanical properties. Fracture sliding occurs in the direction of maximum resolved shear stress. Nonlinear empirical relations are used to relate normal stress, fracture opening, and fracture sliding to fracture aperture and transmissivity. Fluid leakoff is treated with a semianalytical one-dimensional leakoff model that accounts for changing pressure in the fracture over time. Fracture propagation is treated with linear elastic fracture mechanics. Non-Darcy pressure drop in the fractures due to high flow rate is simulated using Forchheimer's equation. A crossing criterion is implemented that predicts whether propagating hydraulic fractures will cross natural fractures or terminate against them, depending on orientation and stress anisotropy. Height containment of propagating hydraulic fractures between bedding layers can be modeled with a vertically heterogeneous stress field or by explicitly imposing hydraulic fracture height containment as a model assumption. The code is efficient enough to perform field-scale simulations of hydraulic fracturing with a discrete fracture network containing thousands of fractures, using only a single compute node. Limitations of the model are that all fractures must be vertical, the mechanical calculations assume a linearly elastic and homogeneous medium, proppant transport is not included, and the locations of potentially forming hydraulic fractures must be specified in advance. Simulations were performed of a single propagating hydraulic fracture with and without leakoff to validate the code against classical analytical solutions. Field-scale simulations were performed of hydraulic fracturing in a densely naturally fractured formation. The simulations demonstrate how interaction with natural fractures in the formation can help explain the high net pressures, relatively short fracture lengths, and broad regions of microseismicity that are often observed in the field during stimulation in low permeability formations, and which are not predicted by classical hydraulic fracturing models. Depending on input parameters, our simulations predicted a variety of stimulation behaviors, from long hydraulic fractures with minimal leakoff into surrounding fractures to broad regions of dense fracturing with a branching network of many natural and newly formed fractures.

Permeability tensors of three-dimensional numerically grown geomechanical discrete fracture networks

2020 ◽  
Author(s):  
Adriana Paluszny ◽  
Robin N Thomas ◽  
Robert W Zimmerman
Keyword(s):  
Stress Intensity ◽  
Hydraulic Properties ◽  
Three Dimensional ◽  
Local Stress ◽  
Fracture Networks ◽  
Intensity Factors ◽  
Dense Networks ◽  
Fracture Patterns ◽  
Discrete Fracture Networks ◽  
Discrete Fracture

<p>The mechanics of fracture propagation and interaction influence the growth and permeability of developing fracture networks. A set of initial flaws grows quasi-statically in response to a remote tensile stress. A finite element, stress intensity factor-based approach grows these flaws into non-planar three-dimensional discrete fracture networks (GDFNs). Their extension and growth angle is a function of local stress intensity factors along a fracture tip. Stress concentration increase when proximal fractures are aligned, and decreases when they are sub-coplanar. These interactions can result in the reactivation of fractures that were initially inactive, and the arrest of fractures that become entrapped by proximal growing fractures. Interaction can cause growth away from an intersection front between two fractures, resulting in evolving fracture patterns that become non-uniform and non-planar, forming dense networks. These GDFNs provide representations of subsurface networks that numerically model the physical process of concurrent fracture growth. Permeability tensors of the geomechanical 3D networks are computed, assuming Darcy flow. Growth influences apertures, and in turn, the hydraulic properties of the network. GDFNs provide a promising way to model subsurface fracture networks, and their related hydro-mechanical processes, where fracture mechanics is the primary influence on the geometric and hydraulic properties of the networks.</p>

scholarly journals Characterizing the impact of particle behavior at fracture intersections in three-dimensional discrete fracture networks

2019 ◽  
Vol 99 (1) ◽  
Author(s):  
Thomas Sherman ◽  
Jeffrey D. Hyman ◽  
Diogo Bolster ◽  
Nataliia Makedonska ◽  
Gowri Srinivasan
Keyword(s):  
Three Dimensional ◽  
Fracture Networks ◽  
Particle Behavior ◽  
Discrete Fracture Networks ◽  
Discrete Fracture ◽  
The Impact
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