Modelling fluid injection-induced fracture activation, damage growth, seismicity occurrence and connectivity change in naturally fractured rocks

Lei, Qinghua; Doonechaly, Nima Gholizadeh; Tsang, Chin‐Fu

doi:10.1016/j.ijrmms.2020.104598

Cited by 81 publications

(23 citation statements)

References 51 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…This interaction (shadowing) can not be observed in a pure fluid diffusion process where this kind of coupling is neglected. Moreover, some researchers have also shown that the isolated fractures can not only be constricted but also be activated when considering shear dilation effects [45][46][47]. Figures 11 and 12 demonstrate that the phase field model can easily address a discontinuous displacement field across fracture surfaces.…”

Section: Sneddon's Pressurizedmentioning

confidence: 93%

Iteratively Coupled Flow and Geomechanics in Fractured Poroelastic Reservoirs: A Phase Field Fracture Model

et al. 2021

View full text Add to dashboard Cite

Fluid-solid coupling in fractured reservoirs plays a critical role for optimizing and managing in energy and geophysical engineering. Computational difficulties associated with sharp fracture models motivate phase field fracture modeling. However, for geomechanical problems, the fully coupled hydromechanical modeling with the phase field framework is still under development. In this work, we propose a fluid-solid fully coupled model, in which discrete fractures are regularized by the phase field. Specifically, this model takes into account the complex coupled interaction of Darcy-Biot-type fluid flow in poroelastic media, Reynolds lubrication governing flow inside fractures, mass exchange between fractures and matrix, and the subsequent geomechanical response of the solid. An iterative coupling method is developed to solve this multifield problem efficiently. We present numerical studies that demonstrate the performance of our model.

show abstract

Section: Sneddon's Pressurizedmentioning

confidence: 93%

Iteratively Coupled Flow and Geomechanics in Fractured Poroelastic Reservoirs: A Phase Field Fracture Model

et al. 2021

View full text Add to dashboard Cite

show abstract

“…Based upon outcomes from this cleat-scale modelling work, future work includes the use of the coupled hydromechanical model developed to carry out engineering-scale modelling of excavation-related gas flow behaviour using large-scale coal fracture networks. The capability of our model to study field-scale problems has already been demonstrated in our recent work of fluid injection into fractured crystalline rocks (Lei et al 2021). Coal fractures patterns may be derived from surface outcrops of coal deposits reconstructed using laser scanning, or underground coal fracture systems captured by borehole logging/geophysical techniques such as 3D seismic, ground penetrating radar and electrical exploration (Pan et al 2019(Pan et al , 2020.…”

Section: Representativeness Of the Coal Cleat Patternmentioning

confidence: 93%

“…and fluid flow behaviour in fractured media. Furthermore, a detailed validation of additional aspects of this hydromechanical coupling model can be found in Lei et al (2021). We then investigate the behaviour of fractured coals based on a laboratory-scale coal sample embedded with a clear cleat pattern (Fig.…”

Section: Coal Cleat Pattern and Propertiesmentioning

confidence: 99%

Stress-Dependent Deformation and Permeability of a Fractured Coal Subject to Excavation-Related Loading Paths

2021

Self Cite

View full text Add to dashboard Cite

The deformation and permeability of coal are largely affected by the presence and distribution of natural fractures such as cleats and bedding planes with orthogonal and abutting characteristics, resulting in distinct hydromechanical responses to stress loading during coal mining processes. In this research, a two-dimensional (2D) fracture network is constructed based on a real coal cleat trace data collected from the Fukang mine area, China. Realistic multi-stage stress loading is designed to sequentially mimic an initial equilibrium phase and a mining-induced perturbation phase involving an increase of axial stress and a decrease of confining stress. The geomechanical and hydrological behaviour of the fractured coal under various stress loading conditions is modelled using a finite element model, which can simulate the deformation of coal matrix, the shearing and dilatancy of coal cleats, the variation of cleat aperture induced by combined effects of closure/opening, and shear and tensile-induced damage. The influence of different excavation stress paths and directions of mining is further investigated. The simulation results illustrate correlated variations among the shear-induced cleat dilation, damage in coal matrix, and equivalent permeability of the fractured coal. Model results are compared with results of previous work based on conventional approaches in which natural fracture networks are not explicitly represented. In particular, the numerical model reproduces the evolution of equivalent permeability under the competing influence of the effective stress perpendicular to cleats and shear-induced cleat dilation and associated damage. Model results also indicate that coal mining at low stress rates is conducive to the stability of surrounding coal seams, and that coal mining in parallel to cleat directions is desirable. The research findings of this paper have important implications for efficient and safe exploitation of coal and coalbed methane resources.

show abstract

“…Of these, hydraulic stimulation is the most commonly used one in both conventional oil and gas industry and in unconventional gas or shale gas development. In this approach, a large amount of fluid is injected into the target reservoir from a packeredoff section of a borehole, and the resulting high pressure cracks the rock creating new tensile fractures and, if a number of natural fractures are present, it may also cause opening and/or shear of these natural fractures (Ghassemi 2012;McClure and Horne 2014a, b;Elsworth et al 2016;Lei et al 2021). Increased permeability is a result from this tensile fracture aperture opening and the shear dilation of the existing fractures.…”

Section: Article Highlightsmentioning

confidence: 99%

“…More recently, an earthquake in the Pohang geothermal field in South Korea in November 2017, with a magnitude of M w 5.5, also directly resulted in the suspension of the Pohang geothermal project (Grigoli et al 2018). To mitigate seismic risks associated with EGS development, significant research effort has lately been invested into understanding the mechanisms related to fluid injection-induced seismicity (Atkinson et al 2020;Schultz et al 2020;Lei et al 2021;.…”

Section: Article Highlightsmentioning

confidence: 99%

Hydraulic stimulation strategies in enhanced geothermal systems (EGS): a review

Jia

Tsang

Hammar

et al. 2022

Geomech. Geophys. Geo-energ. Geo-resour.

Self Cite

View full text Add to dashboard Cite

In enhanced geothermal systems (EGS), the natural permeability of deep rocks is normally not high enough and needs to be increased. Permeability increase can be achieved through various stimulation methods, such as hydraulic, chemical, and thermal stimulation. Among these, hydraulic stimulation is the most commonly used technique to increase both reservoir permeability and the specific area for heat exchange. A comprehensive understanding of the underlying processes towards an optimization of hydraulic stimulation performance while minimizing the potential of unwanted induced seismicity is a critical prerequisite for a successful development of any EGS site. In this paper, we review the hydraulic stimulation strategies that have been developed and implemented for EGS. We begin with a description of the underlying mechanisms through which the permeability and heat exchange area increases are achieved. We then discuss the mechanisms of fluid injection-induced seismicity during and after a hydraulic stimulation operation. After that, alternative hydraulic stimulation strategies, namely conventional hydraulic stimulation, multi-stage fracturing, and cyclic soft stimulation, are reviewed based on current research in theoretical studies as well as, laboratory, and in-situ field experiments. Finally, some representative EGS projects are reviewed, focusing on fluid injection strategies, seismic responses, and reservoir permeability enhancement performance. The review shows the importance and need of (a) a comprehensive geological characterization of the natural fracture system including the nearby fault zones as well as the in-situ stress conditions, prior to the development of the site, (b) a proper design of the well arrangement, such as the positioning of the injection and production wells, and (c) the selection of an appropriate fluid injection strategy for the system at hand.

show abstract

Modelling fluid injection-induced fracture activation, damage growth, seismicity occurrence and connectivity change in naturally fractured rocks

Cited by 81 publications

References 51 publications

Iteratively Coupled Flow and Geomechanics in Fractured Poroelastic Reservoirs: A Phase Field Fracture Model

Iteratively Coupled Flow and Geomechanics in Fractured Poroelastic Reservoirs: A Phase Field Fracture Model

Stress-Dependent Deformation and Permeability of a Fractured Coal Subject to Excavation-Related Loading Paths

Hydraulic stimulation strategies in enhanced geothermal systems (EGS): a review

Contact Info

Product

Resources

About