Article
Thermodynamics
Lei Hou, Derek Elsworth, Fengshou Zhang, Zhiyuan Wang, Jianbo Zhang
Summary: This study proposes a new data-driven workflow, combining numerical models and ensemble learning algorithm, to predict the proportion of proppant-filled fractures in the reservoir. The algorithm performance is improved using variable importance measure and a backward elimination strategy. The predicted proppant filling index quantitatively evaluates the proppant injection and reveals any mismatch between proppant injection and underground fractures.
Article
Energy & Fuels
Yifeng Shen, Youhong Sun, Guobiao Zhang, Yun Qi, Hengfeng Shan, Bing Li
Summary: Hydraulic fracturing is a promising technique for improving gas productivity and energy efficiency in low-permeability hydrate reservoirs. However, the impact of fracturing fluids on hydrate reservoirs has not been well studied. This research simulated the invasion of fracturing fluid into hydrate reservoirs and found that it can cause phase transitions and affect fracturing. The results provide important guidance for the application of hydraulic fracturing in field tests of hydrate reservoirs.
Article
Engineering, Civil
Siavash Taghipoor, Morteza Roostaei, Arian Velayati, Atena Sharbatian, Dave Chan, Alireza Nouri
Summary: This study numerically investigates hydraulic fracturing in oil sands during cold water injection by considering both geomechanics and reservoir fluid flow. It reveals that low shear strengths of unconsolidated or weakly consolidated sandstone reservoirs significantly influence the hydraulic fracturing process. The study employs a smeared fracture technique to simulate tensile and shear fractures in oil sands, combining various fracture features and performing sensitivity analyses on reservoir and geomechanical parameters.
Article
Materials Science, Multidisciplinary
Alexandre Guevel, Yue Meng, Christian Peco, Ruben Juanes, John E. Dolbow
Summary: A Darcy-Cahn-Hilliard model coupled with damage is developed to describe multiphase-flow and fluid-driven fracturing in porous media. The model is calibrated against experimental results, recovering a phase diagram differentiating different flow regimes and suggesting a new flow regime.
JOURNAL OF THE MECHANICS AND PHYSICS OF SOLIDS
(2023)
Article
Multidisciplinary Sciences
Zhiyuan Liu, Meizhu Zhang, Lei Sun, Shen Ye, Zitao Chen, Xuhai Tang
Summary: This study proposes a method to predict the properties of natural joints based on the characteristics of fracturing curves. Simulation results show that the fracturing curves undergo significant changes when hydraulic fractures connect to natural joints. Based on the simulation results, an inversion algorithm using the gradient descent method was developed to predict the properties of natural joints.
ARABIAN JOURNAL FOR SCIENCE AND ENGINEERING
(2023)
Article
Engineering, Chemical
Yuting Pan, Xinfang Ma, Jianmin Li, Bobo Xie, Dong Xiong
Summary: Mahu conglomerate oilfield, characterized by strong heterogeneity, commonly uses large-scale hydraulic fracturing for reservoir reconstruction. A finite element model is established using Python programming, considering the random distribution of gravel position and size, to study the geometry of hydraulic fractures in the gravel reservoir. The results show that hydraulic fractures mainly spread around the gravel and their propagation path is affected by the horizontal stress difference. The strength of conglomerate and gravel determines whether hydraulic fractures can penetrate or stop expanding.
Article
Engineering, Multidisciplinary
Dan Zhang, Liangping Yi, Zhaozhong Yang, Xiaogang Li, Feng Zhang
Summary: A novel phase field model based on the interaction between solid and pore fluids is proposed to simulate hydraulic fracture propagation in poro-elastic media. The model considers two-phase fluid flow following Darcy's law with capillary pressure and introduces an anisotropic relative permeability model related to fluid saturation. The driving force and Biot's modulus vary with the phase field and fluid saturation. Displacement, pressure, and saturation are solved in a staggered manner using finite element numerical discretisation and Newton-Raphson iterative methods. The model's correctness is verified, and the limitations of single-phase flow models are revealed. The study also investigates the influence of different matrix permeabilities, water saturations, and stress differences on hydraulic fracture propagation in porous media.
COMPUTER METHODS IN APPLIED MECHANICS AND ENGINEERING
(2023)
Article
Engineering, Chemical
Duo Wang, Sanbai Li, Dongxiao Zhang, Zhejun Pan
Summary: The transport mechanism of densely-packed proppant bed is numerically investigated using the lattice Boltzmann-discrete element coupling method (LB-DEM). This study focuses on the bedload transport of settled proppants in the primary fracture. The results show a nonlinear relationship between particle flux and fluid flux, which is attributed to the shear-thinning property of the proppant bed. The research contributes to an improved hydraulic fracturing operation by optimizing the fracturing fluid injection scheme and proppant flowback control.
Article
Mechanics
G. L. Manjunath, Zhongqi Liu, Birendra Jha
Summary: We present a novel experimental and modeling approach for lab-scale multistage hydraulic fracturing in PMMA and study pressure-based methods for monitoring the process. Our results show injection-induced rotational deformation and asymmetric growth of the hydraulic fracture. We also identify the role of undrained deformation in generating pressure responses at the monitoring well. This study demonstrates the usefulness of lab-scale hydraulic fracturing in estimating the geometry and properties of hydraulic fractures using pressure data from offset wells.
ENGINEERING FRACTURE MECHANICS
(2023)
Article
Energy & Fuels
Diguang Gong, Junbin Chen, Cheng Cheng, Yuanyuan Kou, Haiyan Jiang, Jianhong Zhu
Summary: This study establishes a numerical model to investigate the fracture propagation mechanism in radial well deflagration fracturing. The effects of horizontal principal stress difference, natural fracture distribution, and micro-fractures around the wellbore on fracture propagation are studied. The results provide insights into optimizing deflagration fracturing in radial wells.
Article
Engineering, Mechanical
Peng-Fei Yin, Sheng-Qi Yang, Feng Gao, Wen-Ling Tian, Wei Zeng
Summary: Understanding the distribution characteristics of hydraulic fracture networks in shale reservoirs is crucial for optimizing fracturing design and production estimation. By improving the fluid-solid coupling model and studying key factors affecting fracture propagation, a numerical model is established to analyze the distribution characteristics of the fracture network in staged fracturing. The results show that coalescence of interbedding fractures plays a significant role in forming an effective fracture network for shale gas exploitation.
THEORETICAL AND APPLIED FRACTURE MECHANICS
(2023)
Article
Physics, Multidisciplinary
Yuqiang Xu, Qiandeng Li, Bingshuo Li, Zhichuan Guan
Summary: The study shows that the erosion velocity of hydraulic jet fracturing nozzles is influenced by factors such as inlet pressure, erosion time, fluid viscosity, erosion particle diameter, and mass flow rate. The size and mass flow rate of the erosion particles are the main factors affecting the erosion effect of the nozzle.
FRONTIERS IN PHYSICS
(2022)
Article
Energy & Fuels
Minghui Li, Fujian Zhou, Lishan Yuan, Liang Chen, Xiaodong Hu, Guopeng Huang, Shaobo Han
Summary: This study investigates the competitive propagation of multiple fractures in heterogeneous layered formations, revealing the impact of geological parameters on fracture pressure, fluid volume, and fracture length. The findings offer valuable insights for design of separate-layer fracturing in such formations.
Article
Chemistry, Multidisciplinary
Tamas Lengyel, Attila Varga, Ferenc Safranyik, Anita Jobbik
Summary: Hydraulic fracturing is a well-known production intensification technique in the petroleum industry that aims to enhance well productivity. The method developed in this article combines Discrete Element Method and Finite Element Method to describe fracture behavior. By comparing numerical model results with laboratory data, the effectiveness of the method was validated, providing new perspectives for explorers and engineers in understanding propped hydraulic fracture operation.
APPLIED SCIENCES-BASEL
(2021)
Article
Engineering, Chemical
Yanxin Zhao, Lei Wang, Kuo Ma, Feng Zhang
Summary: This study simulated and analyzed the hydraulic fracture propagation in continental shale reservoirs, and investigated the influence of different geological and engineering parameters on the propagation process. The results show that interfacial cementation strength, vertical stress difference, interlaminar stress difference, tensile strength difference, elastic modulus, fracturing fluid viscosity, and injection displacement all have an impact on the penetration and expansion of hydraulic fractures.
Article
Physics, Multidisciplinary
N. R. Brodnik, S. Brach, C. M. Long, G. Ravichandran, B. Bourdin, K. T. Faber, K. Bhattacharya
Summary: Fracture toughness of a material can be asymmetric, with the resistance of a medium to crack propagation varying depending on the direction. This can be achieved by controlling microstructure, allowing for guided crack paths to minimize loss of critical components.
PHYSICAL REVIEW LETTERS
(2021)
Article
Engineering, Geological
Ryota Goto, Noriaki Watanabe, Kiyotoshi Sakaguchi, Takahiro Miura, Youqing Chen, Takuya Ishibashi, Eko Pramudyo, Francesco Parisio, Keita Yoshioka, Kengo Nakamura, Takeshi Komai, Noriyoshi Tsuchiya
Summary: Research has shown that in superhot geothermal environments, hydraulic fracturing can form a dense network of permeable fractures known as a cloud-fracture network. Experimental support for the use of the Griffith failure criterion as a plausible criterion for cloud-fracture network formation has been provided. This study provides the theoretical basis needed to establish the procedure for hydraulic fracturing in superhot EGS for the first time.
ROCK MECHANICS AND ROCK ENGINEERING
(2021)
Article
Environmental Sciences
Olaf Kolditz, Thomas Fischer, Thomas Fruehwirt, Uwe-Jens Goerke, Carolin Helbig, Heinz Konietzky, Jobst Massmann, Mathias Nest, Daniel Poetschke, Karsten Rink, Am Ir Sattari, Patrick Schmidt, Holger Steeb, Frank Wuttke, Keita Yoshioka, Bernhard Vowinckel, Gesa Ziefle, Thomas Nagel
Summary: This paper provides an overview of the GeomInt project conducted within the Geo:N Geosciences for Sustainability program from 2017-2020. The research concept focuses on geological discontinuities and aims to make the results more generally applicable through a generic framework. The development of models and experiments cover various fundamental fracturing mechanisms and have been demonstrated in field-scale applications.
ENVIRONMENTAL EARTH SCIENCES
(2021)
Article
Environmental Sciences
Keita Yoshioka, Amir Sattari, Mathias Nest, Ralf-Michael Guenther, Frank Wuttke, Thomas Fischer, Thomas Nagel
Summary: The success of energy transition depends on subsurface exploitation, which can store energy dense fluids and sequester unwanted substances. However, these operations can cause changes in subsurface pressure and temperature, affecting surrounding formations. Ensuring operational safety requires maintaining subsurface integrity. This study compared three computational approaches for assessing fracturing risk without prior knowledge of crack initiation locations or propagation paths, and evaluated their predictive capabilities against percolation experiments on rock salt.
ENVIRONMENTAL EARTH SCIENCES
(2022)
Article
Energy & Fuels
K. Furui, T. Abe, T. Watanabe, K. Yoshioka
Summary: Fluid flow in geologic formations can lead to the formation of wormholes, which are dendritic patterns formed by mineral dissolution. This study focuses on the process instability driven by reaction-infiltration and applies a phase-field approach to simulate wormhole formation. The results show that the model is capable of accurately predicting the growth patterns of wormholes.
JOURNAL OF PETROLEUM SCIENCE AND ENGINEERING
(2022)
Article
Energy & Fuels
Ryota Goto, Kiyotoshi Sakaguchi, Francesco Parisio, Keita Yoshioka, Eko Pramudyo, Noriaki Watanabe
Summary: The success of supercritical/superhot geothermal energy production relies on successful drilling. This study investigates wellbore stability in supercritical environments and finds that wellbore failure occurs at stress states consistent with existing brittle failure criterion at the studied temperatures. Shear failure propagation is suppressed at high temperatures, making it difficult to estimate in situ stress using breakout geometry. However, boreholes may be inherently stable in high-temperature environments.
Article
Materials Science, Multidisciplinary
Erwan Tanne, Blaise Bourdin, Keita Yoshioka
Summary: The process of hydraulic fracturing typically generates asymmetric crack growth in toughness dominated conditions, rather than as a result of material heterogeneities. This challenges the common assumption of symmetrical growth in hydraulic fractures and suggests another source of instability beyond material heterogeneity.
INTERNATIONAL JOURNAL OF FRACTURE
(2022)
Article
Computer Science, Interdisciplinary Applications
Andrew Akerson, Blaise Bourdin, Kaushik Bhattacharya
Summary: With recent advances in responsive materials and fabrication techniques, integrated functional structures composed of structural and active materials can now be constructed. This study investigates the robust design of such structures through topology optimization, exploring different objective functions and their resulting designs.
STRUCTURAL AND MULTIDISCIPLINARY OPTIMIZATION
(2022)
Article
Computer Science, Interdisciplinary Applications
Nha Van Tran, Blaise Bourdin
Summary: We propose a new approach to optimal design with state constraints based on active set optimization theory, and implement it using a phase-field model. Our main objective is to minimize the compliance subject to inner and outer obstacles. We compare our approach to a classical penalization method and investigate the influence of initial guess, penalization parameters, and discretization.
STRUCTURAL AND MULTIDISCIPLINARY OPTIMIZATION
(2022)
Article
Engineering, Geological
Xiaoxuan Li, Hannes Hofmann, Keita Yoshioka, Yongjiang Luo, Yunpei Liang
Summary: Hydraulic fracturing is a widely used technique in unconventional reservoirs. The interactions between hydraulic fracture and natural fracture can have a significant impact on the fracture patterns and subsequent productivity. In this study, a phase-field model is used to investigate the influence of in-situ stress, fracturing operational parameters, and natural fracture orientation and strength on the fracture propagation path. The results provide insights into the mechanism behind different propagation patterns and factors affecting fracture complexity.
ROCK MECHANICS AND ROCK ENGINEERING
(2022)
Article
Engineering, Geological
Keita Yoshioka, Yixuan Zhang, Guanyi Lu, Andrew Bunger, Jose Adachi, Blaise Bourdin
Summary: Experimental studies have shown that the fracture toughness of rocks increases with the confining pressure. The burst experiment is a widely used method to quantify this relationship. However, traditional interpretations of the critical pressure in this experiment may lead to overestimation of fracture toughness. This study proposes modifications to the experimental design to improve the consistency of results and supports the claim with acoustic emission recordings.
ROCK MECHANICS AND ROCK ENGINEERING
(2023)
Article
Materials Science, Multidisciplinary
Vahid Ziaei-Rad, Mostafa Mollaali, Thomas Nagel, Olaf Kolditz, Keita Yoshioka
Summary: We propose a decomposition method for constitutive relations in the phase field approach to fracture, specifically designed for anisotropic/orthotropic materials to account for tension-compression asymmetry. This method retains the anisotropic behavior and tension-compression asymmetry in the crack response. In addition, we modify the energy release computation to accurately predict fracture propagation direction.
JOURNAL OF THE MECHANICS AND PHYSICS OF SOLIDS
(2023)
Article
Mathematics, Interdisciplinary Applications
Frederic Marazzato, Blaise Bourdin
Summary: Variational phase-field models are commonly utilized to simulate crack evolution in brittle materials, approximating the solutions of fracture energy with smooth displacement and damage fields. This article proposes a nonconforming approximation method using discontinuous elements for displacement and elements with more isotropic gradients for damage, derived from the handling of heterogeneous diffusion problems. The robustness and versatility of the method are demonstrated through various examples.
COMPUTATIONAL MECHANICS
(2023)
Article
Geochemistry & Geophysics
Keita Yoshioka, Masafumi Katou, Kohei Tamura, Yutaro Arima, Yoshiharu Ito, Youqing Chen, Tsuyoshi Ishida
Summary: Hydraulic fractures often interact with preexisting discontinuities in the rock mass, and the criteria for fracture penetration or deflection are typically based on the in situ stress and the characteristics of the discontinuities. However, experiments on carbonate rocks show that fractures more frequently deflect at grain boundaries as they propagate farther from the wellbore, which is not explained by the conventional criteria. Our study demonstrates that the energy dissipation of a deflecting fracture increases with the distance from the wellbore, making it energetically more favorable for a fracture to deflect at a discontinuity. This highlights the importance of energetic stability analysis for determining fracture paths.
JOURNAL OF GEOPHYSICAL RESEARCH-SOLID EARTH
(2023)
