Arbitrary Fracture Propagation in Heterogeneous Poroelastic Formations Using a Finite Volume-Based Cohesive Zone Model

2015 ◽  
Author(s):  
Eric C Bryant ◽  
Jongsoo Hwang ◽  
Mukul Mani Sharma
Keyword(s):  
Finite Volume ◽  
Cohesive Zone ◽  
Cohesive Zone Model ◽  
Fracture Propagation ◽  
Zone Model

Arbitrary Fracture Propagation in Heterogeneous Poroelastic Formations Using a Finite Volume-Based Cohesive Zone Model

2015 ◽  
Author(s):  
Eric C. Bryant ◽  
Jongsoo Hwang ◽  
Mukul M. Sharma
Keyword(s):  
Finite Volume ◽  
Cohesive Zone ◽  
Cohesive Zone Model ◽  
Fracture Propagation ◽  
In Situ Stress ◽  
Propagation Model ◽  
Zone Model ◽  
Bedding Planes ◽  
Stress Contrast

Abstract A finite volume-based arbitrary fracture propagation model is used to simulate fracture growth and geomechanical stresses during hydraulic fracture treatments. Single-phase flow, poroelastic displacement, and in-situ stress tensor equations are coupled within a poroelastic reservoir domain, using a fixed-strain split assumption. The domain is idealized as two-dimensional and plane-strain, with heterogeneous elastic material and fracture toughness properties. Fracture propagation proceeds by failure along finite volume cells in excess of a threshold effective stress. The cohesive zone model (CZM) is used to simulate propagation of non-planar fractures in heterogeneous porous media under uniform, anisotropic stresses. In addition the model computes the stress field and the pore pressure in the rock matrix to account for stress interference effects. This allows us to estimate the simulated micro-seismic signature of the rock during fracturing. Results show that the presence of bedding planes or planes of weakness in the rock can lead to complex fracture trajectories. The growth of multiple, non-intersecting, competing fractures is also simulated. It is shown that the fracture geometry obtained using this model is highly dependent on the pattern of heterogeneity. For homogeneous reservoirs and a high in-situ stress contrast, planar fractures are obtained. As the stress contrast is decreased and the degree of heterogeneity is increased, fracture complexity increases. Results for different kinds and levels of formation heterogeneity; planes-of-weakness such as bedding planes or natural fracture networks, and layers with different mechanical properties are presented. This model allows for first-of-kind simulation of fracture propagation with arbitrary geometry in a poroelastic solid domain, using proven computational finite volume methods (FVM). The effect of fluid backpressure, mechanical stress shadow effects, and formation heterogeneity are accounted for. The importance of critical stresses on fracture path is discussed.

Cohesive Zone-Based Damage Evolution in Periodic Materials Via Finite-Volume Homogenization

2014 ◽  
Vol 81 (10) ◽  
Author(s):  
Wenqiong Tu ◽  
Marek-Jerzy Pindera
Keyword(s):  
Finite Volume ◽  
Cohesive Zone ◽  
Cohesive Zone Model ◽  
Displacement Discontinuity ◽  
Zone Model ◽  
Infinite Matrix ◽  
Unified Framework ◽  
Linear Region ◽  
Interfacial Separation ◽  
Periodic Materials

The zeroth-order parametric finite-volume direct averaging micromechanics (FVDAM) theory is further extended in order to model the evolution of damage in periodic heterogeneous materials. Toward this end, displacement discontinuity functions are introduced into the formulation, which may represent cracks or traction-interfacial separation laws within a unified framework. The cohesive zone model (CZM) is then implemented to simulate progressive separation of adjacent phases or subdomains. The new capability is verified in the linear region upon comparison with an exact elasticity solution for an inclusion surrounded by a linear interface of zero thickness in an infinite matrix that obeys the same law as CZM before the onset of degradation. The extended theory's utility is then demonstrated by revisiting the classical fiber/matrix debonding phenomenon observed in SiC/Ti composites, illustrating its ability to accurately capture the mechanics of progressive interfacial degradation.

scholarly journals Using Cohesive Zone Model to Simulate the Hydraulic Fracture Interaction with Natural Fracture in Poro-Viscoelastic Formation

Energies ◽  
2019 ◽  
Vol 12 (7) ◽  
pp. 1254 ◽  
Author(s):  
Yu Suo ◽  
Zhixi Chen ◽  
Hao Yan ◽  
Daobing Wang ◽  
Yun Zhang
Keyword(s):  
Numerical Model ◽  
Pore Pressure ◽  
Hydraulic Fracture ◽  
Cohesive Zone ◽  
Cohesive Zone Model ◽  
Fracture Propagation ◽  
Natural Fracture ◽  
Zone Model ◽  
Fluid Viscosity ◽  
Fluid Diffusion

Hydraulic fracturing is a widely used production stimulation technology for conventional and unconventional reservoirs. The cohesive element is used to explain the tip fracture process. In this paper, the cohesive zone model was used to simulate hydraulic fracture initiation and propagation at the same time rock deformation and fluid exchange. A numerical model for fracture propagation in poro-viscoelastic formation is considered. In this numerical model, we incorporate the pore-pressure effect by coupling fluid diffusion with shale matrix viscoelasticity. The numerical procedure for hydraulically driven fracture propagation uses a poro-viscoelasticity theory to describe the fluid diffusion and matrix creep in the solid skeleton, in conjunction with pore-pressure cohesive zone model and ABAQUS was used as a platform for the numerical simulation. The simulation results are compared with the available solutions in the literature. The higher the approaching angle, the higher the differential stress, tensile stress difference, injection rate, and injection fluid viscosity, and it will be easier for hydraulic fracture crossing natural fracture. These results could provide theoretical guidance for predicting the generation of fracture network and gain a better understanding of deformational behavior of shale when fracturing.

scholarly journals Ultrasonic Deicing Efficiency Prediction and Validation for a Flat Deicing System

2020 ◽  
Vol 10 (19) ◽  
pp. 6640
Author(s):  
Zhonghua Shi ◽  
Zhenhang Kang ◽  
Qiang Xie ◽  
Yuan Tian ◽  
Yueqing Zhao ◽  
...  
Keyword(s):  
Lead Zirconate Titanate ◽  
Cohesive Zone ◽  
Cohesive Zone Model ◽  
Lead Zirconate ◽  
Efficiency Factor ◽  
Zone Model ◽  
Shear Stresses ◽  
Stress Distributions ◽  
Total Energy Density ◽  
Average Shear

An effective deicing system is needed to be designed to conveniently remove ice from the surfaces of structures. In this paper, an ultrasonic deicing system for different configurations was estimated and verified based on finite element simulations. The research focused on deicing efficiency factor (DEF) discussions, prediction, and validations. Firstly, seven different configurations of Lead zirconate titanate (PZT) disk actuators with the same volume but different radius and thickness were adopted to conduct harmonic analysis. The effects of PZT shape on shear stresses and optimal frequencies were obtained. Simultaneously, the average shear stresses at the ice/substrate interface and total energy density needed for deicing were calculated. Then, a coefficient named deicing efficiency factor (DEF) was proposed to estimate deicing efficiency. Based on these results, the optimized configuration and deicing frequency are given. Furthermore, four different icing cases for the optimize configuration were studied to further verify the rationality of DEF. The effects of shear stress distributions on deicing efficiency were also analyzed. At same time, a cohesive zone model (CZM) was introduced to describe interface behavior of the plate and ice layer. Standard-explicit co-simulation was utilized to model the wave propagation and ice layer delamination process. Finally, the deicing experiments were carried out to validate the feasibility and correctness of the deicing system.

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