The Behaviour of Fracture Growth in Sedimentary Rocks: A Numerical Study Based on Hydraulic Fracturing Processes

Li, Lianchong; Xia, Yingjie; Huang, Bo; Zhang, Liaoyuan; Li, Ming; Li, Aishan

doi:10.3390/en9030169

Cited by 39 publications

(22 citation statements)

References 59 publications

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“…36,37 Additionally, local heterogeneity of the rock matrix and the stress fluctuations because of the variability of material properties cause branching, twisting, and turning of fractures. [38][39][40] Various studies 41,42 have been conducted on the interaction between heterogeneity and hydraulic fracturing. The effect of heterogeneity on mechanical and acoustic emission characteristics of rock specimen was also studied under uniaxial compression using numerical simulations.…”

Section: Introductionmentioning

confidence: 99%

Simulating damage evolution and fracture propagation in sandstone containing a preexisting 3‐D surface flaw under uniaxial compression

Mondal

Olsen-Kettle

Gross

2019

Num Anal Meth Geomechanics

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Summary Preexisting flaws and rock heterogeneity have important ramifications on the process of rock fracturing and on rock stability in many applications. Therefore, there is great interest in numerical modelling of rock fracture and the underlying mechanisms. We simulated damage evolution and fracture propagation in sandstone specimens containing a preexisting 3‐D surface flaw under uniaxial compression. We applied the linear elastic damage model based on the unified strength theory following the rock failure process analysis code. However, in contrast to the rock failure process analysis code, we used the finite element method with tetrahedron elements on unstructured meshes. It provided higher geometrical flexibility and allowed for a more accurate representation of the disk‐shaped flaw with various flaw depths, angles, and lengths through locally adapted meshes. The rock heterogeneity was modelled by sampling the initial local Young's modulus from a Weibull distribution over a cubic grid. The values were then interpolated to the computational finite element method mesh. This method introduced an additional length scale for the rock heterogeneity represented by the cell size in the sampling grid. The generation of three typical surface cracking patterns, called wing cracks, anti‐wing cracks, and far‐field cracks, were identified in the simulation results. These depend on the geometry of the preexisting surface flaw. The simulated fracture propagation, coalescence types, and failure modes for the specimens with preexisting surface flaw show good agreement with recent experimental studies.

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Section: Introductionmentioning

confidence: 99%

Simulating damage evolution and fracture propagation in sandstone containing a preexisting 3‐D surface flaw under uniaxial compression

Mondal

Olsen-Kettle

Gross

2019

Num Anal Meth Geomechanics

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show abstract

“…So far, some researches have been made on the influence of bedding planes and natural fractures on hydraulic fracture propagation. Regarding the factors affecting hydraulic fracture propagation, Li et al concluded through numerical simulation that the fracture propagation is primarily influenced by original crustal stress, bedding plane quality as well as the lithologic character. Lu et al also drew a conclusion through the same means that horizontal principal stress difference, minimum horizontal principal stress and intersection angle between hydraulic fracture and stratigraphic interface which are the dominant factors that influence fracture propagation and the forms.…”

Section: Introductionmentioning

confidence: 99%

Propagation of hydraulic fracture under the joint impact of bedding planes and natural fractures in shale reservoirs

Gong

Xia

Peng

et al. 2019

Energy Science & Engineering

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The generation of the complex fracture network through hydraulic fracturing is a prerequisite for economic exploitation of shale gas. Bedding planes and natural fractures in shale reservoirs exert a direct impact on the propagation of hydraulic fracture and the formation of the complex fracture network. Based on theoretical analysis and flow‐stress‐damage coupled approach, the propagation of hydraulic fracture under the joint impact of the bedding planes and the natural fractures is studied. The results show the main factors that influence the fracture propagation are the horizontal principal stress difference, the minimum horizontal principal stress, the approaching angle of bedding plane (AABP), the intersection angle of natural fracture (IANF), and the cohesion of the reservoir matrix and the bedding plane. The bigger the horizontal principal stress difference is and the smaller AABP and the cohesion are, the more likely hydraulic fracture will propagate toward the direction of the maximum horizontal principle stress; the smaller AABP and the cohesion are, the more easily it will propagate along the bedding planes; AABP and IANF are the key factors that affect the fracture network formation and both of them bear a negative correlation on the principal stress difference for the formation of the fracture network; the smaller the stress difference and the cohesion difference between the bedding plane and the reservoir matrix are, and AABP is close to IANF and they are in the middle of its value range, the more easily the fracture network forms. The research results are of great significance to reveal the propagation law of hydraulic fracture and the formation of the complex fracture network in shale reservoirs and the efficient exploitation of shale gas.

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“…At present, to enhance gas drainage efficiency in a low-permeability coal seam, hydraulic fracturing (HF) is used as a standard practice [1][2][3]. It achieves good results draining coal bed methane in most coal mines.…”

Section: Introductionmentioning

confidence: 99%

Determination of Fracture Initiation Locations during Cross-Measure Drilling for Hydraulic Fracturing of Coal Seams

Cheng

et al. 2016

Energies

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When drilling coal-bearing sequences to enhance coal seam permeability by hydraulic fracturing (HF), the location where fractures are initiated is important. To date, most research on fracture initiation has studied the problem in two dimensions. In this study, a three-dimensional model to assess initiation location is developed. The model analyzes the stress state of both the borehole wall and the coal-rock interface and the model shows that the fracture initiation location is affected by in situ stress, the dip of the coal seam, and the angle between the borehole and the coal seam. How the initiation location changes near different types of geological faults is calculated by assuming typical in situ stresses for the faults. Following these calculations, physical experiments were carried out to emulate cross-measure hydraulic fracturing under stress conditions equivalent to those in the Chongqing Tonghua coal mine, China. Fracture initiation during the experiments was monitored by an acoustic emission system. The experimental results were consistent with the theoretical calculations. This implies that the three-dimensional model for assessing the locations of fracture initiation can be applied to forecast the initiation location of fractures generated by cross-measure drilling. The assessment model provides reference values for this type of drilling in underground mines.

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The Behaviour of Fracture Growth in Sedimentary Rocks: A Numerical Study Based on Hydraulic Fracturing Processes

Cited by 39 publications

References 59 publications

Simulating damage evolution and fracture propagation in sandstone containing a preexisting 3‐D surface flaw under uniaxial compression

Simulating damage evolution and fracture propagation in sandstone containing a preexisting 3‐D surface flaw under uniaxial compression

Propagation of hydraulic fracture under the joint impact of bedding planes and natural fractures in shale reservoirs

Determination of Fracture Initiation Locations during Cross-Measure Drilling for Hydraulic Fracturing of Coal Seams

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