Study on Experimental Simulation of Rocks under Hydraulic Fracturing

In order to further research the expansion of cracks in the rock during hydraulic fracturing, this paper theoretically analyzes the stress state of wall cracks. According to the effective stress criterion of Terzgahi, it gives the mechanical condition of the rock crack expansion. By Moore-coulomb's law, it analyzes the influence of the water pressure in the pores of space wall on the rock fracturing. On this basis, the hydraulic rock fracturing is applied to build physical experiment model of deep mining mine water bursting. By the methodology of combining the analysis of experimental results and theoretical analysis, it analyzes the change of water injection pressure in the hole with rock fracturing and the stress strain relations during rock’s uniform displacement change and loading. The experimental results show that in the process of the water pressure and vertical loading, the increasing fracture load on the rock, constantly produces, expands the cracks and fractures to instability; the mutual influence of water and pressure comes to be the major problem of deep mining rock fracture and mine water bursting.

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Numerical Simulation and Analysis of Rock under Hydraulic Fracturing Based on Acoustic Emission Monitoring

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.382.458 ◽

2011 ◽

Vol 382 ◽

pp. 458-461

Author(s):

Zhi Qiang Kang ◽

Yun Fei Zhou ◽

Run Sheng Wang

Keyword(s):

Numerical Simulation ◽

Hydraulic Fracturing ◽

Mine Water ◽

Water Pressure ◽

Overburden Rock ◽

Deep Mining ◽

Water Seepage ◽

Vertical Loading ◽

Rock Structure ◽

Fracturing Process

According to the problem of mine water bursting frequent accidents when Mine into the deep mining. Based on the theory of fluid-solid coupling, accounting for the effect on permeability by damage and stress. Analysis of influence factors what hydraulic fracturing process, fracture propagation pattern, and influencing factors including shape and magnitude of inlet hole, stress conditions, and specimen strength were investigated. Hydraulic fracturing is not only a natural action but also an artificial method to alter rock structure. Application of rock failure process analysis software coupled seepage-stress F-RFPA2D, numerical simulated rock water pressure to cause crack rupture instability process, research the fracture law of the rock on water pressure and vertical loading. Combine similar physical experiment model, contrast analysis of two broken results and stress-strain curve, reveals instability mechanical behavior of rock hydraulic fracture process. Obtain deep mining in the process of mine water seepage and water extrude, overburden rock crack up, expand, water seepage, water extrude, instability rupture process rules. numerical simulation results and experimental results has good uniformity, for disaster of the mine water extrude has immeasurable prediction practical.

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The Study of Fractured Rock Mass Instability of the Law Based on the Hydraulic Fracturing

Advanced Materials Research ◽

10.4028/www.scientific.net/amr.496.538 ◽

2012 ◽

Vol 496 ◽

pp. 538-541

Author(s):

Zhi Qiang Kang ◽

Wein Jie Li ◽

Yu Bo Jia

Keyword(s):

Rock Mass ◽

Hydraulic Fracturing ◽

Hydraulic Fracture ◽

Fractured Rock ◽

Water Pressure ◽

Overburden Rock ◽

Fractured Rock Mass ◽

Water Seepage ◽

Vertical Loading ◽

The Law

Fractured rock mass, Hydraulic fracture, RFPA2D-Flow, Instability of the law. Abstract. Based on the theory of fluid-solid coupling, Studying on the effect of permeability about damage and stress, Analysis of influence factors what hydraulic fracturing process, fracture propagation pattern, and influencing factors including shape and magnitude of inlet hole, stress conditions, and specimen strength were investigated. Application of rock failure process analysis software coupled seepage-stress F-RFPA2D, numerical simulated rock water pressure to cause crack rupture instability process, research the fracture law of the rock on water pressure and vertical loading. Combine similar physical experiment model, contrast analysis of two broken results and stress-strain curve, reveals instability mechanical behavior of rock hydraulic fracture process. Obtain deep mining in the process of mine water seepage and water extrude, overburden rock crack up, expand, water seepage, water extrude, instability rupture process rules.

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The alterations of critical pore water pressure and micro-cracking morphology with near-wellbore fractures in hydraulic fracturing of shale reservoirs

Engineering Fracture Mechanics ◽

10.1016/j.engfracmech.2020.107481 ◽

2021 ◽

Vol 242 ◽

pp. 107481

Author(s):

Fakai Dou ◽

J.G. Wang ◽

C.F. Leung ◽

Zhanguo Ma

Keyword(s):

Hydraulic Fracturing ◽

Pore Water ◽

Pore Water Pressure ◽

Water Pressure ◽

Shale Reservoirs

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Investigation of Proppant Distributions in Rock Fractures With Applications to Hydraulic Fracturing

10.1115/fedsm2021-65833 ◽

2021 ◽

Author(s):

Amir A. Mofakham ◽

Farid Rousta ◽

Dustin M. Crandall ◽

Goodarz Ahmadi

Keyword(s):

Fluid Flow ◽

Hydraulic Fracturing ◽

Oil And Gas ◽

Fluid Dynamic ◽

Rock Fracture ◽

Experimental Investigations ◽

Rock Fractures ◽

Fracture Geometry ◽

Injection Process ◽

Fracking Fluid

Abstract Hydraulic fracturing or fracking is a procedure used extensively by oil and gas companies to extract natural gas or petroleum from unconventional sources. During this process, a pressurized liquid is injected into wellbores to generate fractures in rock formations to create more permeable pathways in low permeability rocks that hold the oil. To keep the rock fractures open after removing the high pressure, proppant, which typically are sands with different shapes and sizes, are injected simultaneously with the fracking fluid to spread them throughout rock fractures. The extraction productivity from shale reservoirs is significantly affected by the performance and quality of the proppant injection process. Since these processes occur under the ground and in the rock fractures, using experimental investigations to examine the process is challenging, if not impossible. Therefore, employing numerical tools for analyzing the process could provide significant insights leading to the fracking process improvement. Accordingly, in this investigation, a 4-way coupled Computational Fluid Dynamic and Discrete Element Method (CFD-DEM) code was used to simulate proppant transport into a numerically generated realistic rock fracture geometry. The simulations were carried out for a sufficiently long period to reach the fractures’ steady coverage by proppant. The proppant fracture coverage is a distinguishing factor that can be used to assess the proppant injection process quality. A series of simulations with different proppant sizes as well as various fracking fluid flow rates, were performed. The corresponding estimated fracture coverages for different cases were compared. The importance of proppant size as well as the fluid flow rate on the efficiency of the proppant injection process, were evaluated and discussed.

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Theoretical Modeling of Rock Breakage by Hydraulic and Mechanical Tool

Mathematical Problems in Engineering ◽

10.1155/2014/895835 ◽

2014 ◽

Vol 2014 ◽

pp. 1-9 ◽

Cited By ~ 2

Author(s):

Hongxiang Jiang ◽

Changlong Du ◽

Songyong Liu ◽

Liping Wang

Keyword(s):

Theoretical Model ◽

Water Pressure ◽

Rock Fracture ◽

Superposition Principle ◽

Specific Energy Consumption ◽

Critical Length ◽

Rock Fragmentation ◽

Rock Breakage ◽

Hydraulic Impact ◽

Mechanical Tool

Rock breakage by coupled mechanical and hydraulic action has been developed over the past several decades, but theoretical study on rock fragmentation by mechanical tool with water pressure assistance was still lacking. The theoretical model of rock breakage by mechanical tool was developed based on the rock fracture mechanics and the solution of Boussinesq’s problem, and it could explain the process of rock fragmentation as well as predicating the peak reacting force. The theoretical model of rock breakage by coupled mechanical and hydraulic action was developed according to the superposition principle of intensity factors at the crack tip, and the reacting force of mechanical tool assisted by hydraulic action could be reduced obviously if the crack with a critical length could be produced by mechanical or hydraulic impact. The experimental results indicated that the peak reacting force could be reduced about 15% assisted by medium water pressure, and quick reduction of reacting force after peak value decreased the specific energy consumption of rock fragmentation by mechanical tool. The crack formation by mechanical or hydraulic impact was the prerequisite to improvement of the ability of combined breakage.

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Application of Bionic Technologies on the Fracturing Plug

Biomimetics ◽

10.3390/biomimetics4040078 ◽

2019 ◽

Vol 4 (4) ◽

pp. 78

Author(s):

Lin Chen ◽

Ran Wei ◽

Songbo Wei ◽

Xinzhong Wang

Keyword(s):

Hydraulic Fracturing ◽

Dissolution Rate ◽

Experimental Results ◽

Hydrophobic Properties ◽

Multi Stage ◽

Bionic Surface ◽

Zonal Isolation ◽

Oil Gas

The dissolvable bridge plug is one of the most important tools for multi-stage hydraulic fracturing in the field of oil/gas development. The plug provides zonal isolation to realize staged stimulation and, after fracturing, the plug is fully dissolved in produced liquids. A bionic surface was introduced to improve the performance of the plug. Surface dimples in the micron dimension were prepared on the dissolvable materials of the plug. The experimental results showed that the surface dimples changed the hydrophilic and hydrophobic properties of the dissolvable materials. The dissolution rate has a great relation with the parameters of the dimples and can be controlled by choosing the dimples’ parameters to some degree.

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Experimental study on flow and heat transfer characteristics of water flowing through a rock fracture induced by hydraulic fracturing for an enhanced geothermal system

Applied Thermal Engineering ◽

10.1016/j.applthermaleng.2019.03.114 ◽

2019 ◽

Vol 154 ◽

pp. 433-441 ◽

Cited By ~ 6

Author(s):

Yueqiang Ma ◽

Yanjun Zhang ◽

Yibin Huang ◽

Yu Zhang ◽

Zhongjun Hu

Keyword(s):

Heat Transfer ◽

Experimental Study ◽

Hydraulic Fracturing ◽

Rock Fracture ◽

Geothermal System ◽

Enhanced Geothermal System ◽

Heat Transfer Characteristics ◽

Transfer Characteristics ◽

Flow And Heat Transfer

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Numerical Simulation for Destroy Pattern of Surrounding Rock of Circle Tunnel with M-H Coupling Action

Applied Mechanics and Materials ◽

10.4028/www.scientific.net/amm.71-78.3572 ◽

2011 ◽

Vol 71-78 ◽

pp. 3572-3576

Author(s):

An Nan Jiang ◽

Peng Li

Keyword(s):

Numerical Simulation ◽

Pore Water Pressure ◽

Water Pressure ◽

Rock Fracture ◽

High Stress ◽

Surrounding Rock ◽

Zonal Disintegration ◽

Affecting Factors ◽

Tunnel Wall ◽

Shear Belt

The uniform zonal disintegration of surrounding rock is the peculiar phenomena of deep and high stress field, researching the inner mechanism and affecting factors has important meaning for guaranteeing the safety of deep engineering. The paper adopted strain soft Mohr-Coulomb model and carried out numerical simulation of surrounding rock fracture and excavation. The simulation states that along with the unloading time accumulation, the shear belt produced from tunnel wall and developed to inner rock. The corresponding shear stress concentration zone also spread to inner rock and destroy zone increasing. The pore water pressure increasing will accelerate the shear belt developing and increase the destroy degree.

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Experimental Study on Hydraulic Fracturing of High Asphalt Concrete Core Rock-Fill Dam

Applied Sciences ◽

10.3390/app9112285 ◽

2019 ◽

Vol 9 (11) ◽

pp. 2285 ◽

Cited By ~ 2

Author(s):

Zhengxing Wang ◽

Jutao Hao ◽

Jian Yang ◽

Yan Cao ◽

Xiulin Li ◽

...

Keyword(s):

Hydraulic Fracturing ◽

Hydraulic Fracture ◽

Asphalt Concrete ◽

Water Pressure ◽

Concrete Core ◽

Mix Proportion ◽

Local Shear ◽

Test Result ◽

Rule Out ◽

Shear Dilatancy

In this paper, we experiment on the hydraulic fracturing of asphalt concrete with a voids content higher than 3%, which has arisen from the possible local shear dilatancy of Quxue asphalt’s core wall of concrete core dam, the highest one of the sort constructed in the world. The model test has shown that under the sole water pressure 0.13 MPa—relevant to the pressure where the dilatancy could appear at core wall of Quxue dam—the asphalt concrete with a voids content of 3.5% underwent hydraulic fracturing. Furthermore, the asphalt concrete with a voids content of 3.0% was tested for nearly 500 h and no sign of hydraulic fracturing was found, which again confirmed the threshold requirement for a 3% voids content to the impervious asphalt concrete to the hydraulic fracture concern. According to the analysis of the test result, the theory of fracture mechanics could be applied to the hydraulic fracture of asphalt concrete with a voids content between 3.4~4.0%, which behaved during hydraulic fracturing like a quasi-brittle material, similar to concrete. Because the hydraulic fracturing could occur in the shear dilatant asphalt concrete, a proper mix proportion of asphalt concrete to a project with adverse stress state should be carefully designed to rule out the possibility of shear dilatancy.

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