Laboratory Investigations on the Hydraulic Fracturing of Granite Cores

Zhuang, Łi; Jung, Sung Gyu; Diaz, Melvin; Kim, Kwang Yeom

doi:10.1007/978-3-030-35525-8_4

Cited by 8 publications

(16 citation statements)

References 26 publications

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“…However, MTCs serve several other purposes as well, which are based on observations in laboratory-and mine-scale hydraulic fracturing experiments, and some field examples where cyclic injection was compared to continuous injection. Laboratory experiments performed on different intact rock and cement samples of different sizes under different stress conditions all indicate a systematic reduction in breakdown pressure (Zhuang et al 2016(Zhuang et al , 2017(Zhuang et al , 2018Diaz et al 2018a, b;Patel et al 2016;Tiancheng et al 2018) by up to ~ 24% (Zhuang et al 2016). In mine-scale experiments performed by Zang et al (2017) at the Äspö HRL, the breakdown pressure of the progressive cyclic injection experiment was also lower (9.2 MPa) compared to two continuous injection experiments (13.1 MPa and 10.9 MPa).…”

Section: Medium-term Cycles (Mtcs)mentioning

confidence: 97%

“…In reported experiments, often these cyclic injection effects were increased when more cycles were performed (e.g., Zang et al 2018). For example, Diaz et al (2018a, b) observed a decrease in maximum acoustic emission amplitude, fraction of tensile cracks (compared to shear cracks) and seismic injection efficiency with increasing number of cycles and Zhuang et al (2016) reported development of multiple branching fractures specifically for high cycle numbers. Additionally, they pointed out that such a complex fracture pattern was also observed for a case where 150 cycles were performed without failure followed by monotonic injection until failure.…”

Section: Short-term Cycles (Stcs)mentioning

confidence: 98%

“…At the same time, these laboratory and mine-scale hydraulic fracturing experiments show a reduction of amplitude of the largest seismic event induced by cyclic injection compared to continuous injection by ~ 10% to ~ 30% (Zhuang et al 2017(Zhuang et al , 2018Diaz et al 2018a, b). Additionally, cyclic injection into the same injection interval leads to the development of more complex fracture patterns consisting of more, but shorter and thinner, individual fractures with many branch fractures and more frequent fractures along grain boundaries compared to intragranular cracks (Zhuang et al 2016(Zhuang et al , 2017(Zhuang et al , 2018Zhou et al 2017). Patel et al (2016) found in hydraulic fracturing experiments on sandstone that the damage zone around the hydraulic fracture increased by a factor of two for the cyclic injection test compared to the monotonic injection test.…”

Section: Medium-term Cycles (Mtcs)mentioning

confidence: 99%

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Cyclic soft stimulation (CSS): a new fluid injection protocol and traffic light system to mitigate seismic risks of hydraulic stimulation treatments

et al. 2018

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Economic production of a variety of geological resources, such as shale gas, tight oil, coal bed methane and geothermal heat using enhanced geothermal systems (EGS), relies on hydraulic stimulation treatments. These are reservoir enhancement methods where fluid is injected into a reservoir to increase its productivity by a combination of developing new tensile and shear fractures, and tensile opening and shearing of pre-existing fractures. Stimulated fractures may stay open naturally through the self-propping effect or they have to be kept open artificially by proppants, such as sands or ceramics that are injected together with the stimulation fluid to achieve a permanent productivity enhancement. Details about hydraulic fracturing and other reservoir stimulation methods can be found in an abundance of textbooks and other publications (e.g., Bunger et al. 2013; Economides and Nolte 2000; Economides and Martin 2007; Huenges and Ledru 2010). While improving the hydraulic reservoir performance, hydraulic stimulation treatments also cause fluid-injection-induced seismicity. On the one hand, induced seismicity

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Section: Medium-term Cycles (Mtcs)mentioning

confidence: 97%

Section: Short-term Cycles (Stcs)mentioning

confidence: 98%

Section: Medium-term Cycles (Mtcs)mentioning

confidence: 99%

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Cyclic soft stimulation (CSS): a new fluid injection protocol and traffic light system to mitigate seismic risks of hydraulic stimulation treatments

et al. 2018

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“…With the growing interest in the use of georeservoirs, such cyclic stimulation might be of great interest for future injections. However, only a small number of experimental studies have been performed with the aim of increasing the comprehension of such phenomena, and those were mainly conducted on intact rock samples (Chanard et al, ; Farquharson et al, ; Noël et al, ; Zhuang et al, ).…”

Section: Introductionmentioning

confidence: 99%

Fault Reactivation During Fluid Pressure Oscillations: Transition From Stable to Unstable Slip

et al. 2019

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High-pressure fluid injection in deep georeservoirs can induce earthquakes. Recent observations suggest that cyclic injections might trigger less seismicity than monotonic injections. Here, we report triaxial laboratory experiments conducted on faulted quartz-rich sandstone that provide new insight into the physics of fault-fluid interactions subjected to cyclic fluid pressure variations. The experiments were performed at 30 and 45 MPa confining pressure, imposing constant or sinusoidal fluid pressure oscillations of amplitudes ranging from 0 to 8 MPa in addition to a far-field constant loading rate (10 −4 and 10 −3 mm s −1 ). The results show that (i) in agreement with the Mohr-Coulomb theory, faults reactivate at the static friction criterion, which is generally reached at the maximum fluid pressure during oscillations. (ii) Oscillating fluid pressure perturbations promote seismic behavior rather than aseismic slip, and (iii) increasing the oscillation's amplitude enhances the onset of seismic activity along the fault. We demonstrate that this behavior is caused by slip rate variations resulting from the fluid pressure oscillations. Without fluid pressure oscillations, increasing the far-field loading rate also promotes seismic activity. Our experiments demonstrate that the seismicity intensification due to cyclic fluid injections could be promoted at shallow depth, where confining pressure is relatively low, resulting in large strain rate perturbations.

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“…Using hydraulic loading systems, fracture experiments can be carried out to explore the macromechanical behavior and crack evolution of rock masses under hydraulic pressure. For example, Zhuang et al (2016Zhuang et al ( , 2019 developed hydraulic fracturing test equipment for core rock samples and conducted a series of tests. Using a high-pressure hydromechanical test system, Zhao et al (2017a) performed permeability tests on fractured limestone samples and analyzed the mechanical characteristics and permeability during the stress-strain process.…”

Section: Introductionmentioning

confidence: 99%

Development and Application of a Hydraulic Loading Test System That Provides Continuous and Stable Hydraulic Pressure

Jia-jun

Zhang

2020

Front. Earth Sci.

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To accurately determine the stress characteristics of underground rock masses subjected to hydraulic pressure, and to reveal the crack-initiation, crack-propagation, and macromechanical characteristics of fractured rock masses under long-term hydraulic pressure, a hydraulic loading system that can deliver continuous and stable hydraulic pressure was developed. The system is composed of a device that supplies a stable hydraulic pressure, flowmeter, pressure gauge, acoustic emission instrument, loading device, and control system. The main innovation of the test system lies in the stabilization of the hydraulic pressure, which distinguishes the new system from traditional hydraulic loading devices and provides several advantages. First, in the new system, air pressure serves as the driving force, and water and gas coexist in the same cavity. Given the high compressibility of gas, the hydraulic pressure can still reach relative stability during crack initiation and propagation in the specimen. Second, the device is capable of long-term operation with low energy consumption. In contrast to conventional hydraulic loading systems based on servo control, the hydraulic pressure of the new device can be maintained for a long time with little energy consumption. Finally, the device is simple to operate, is low in cost, convenient to assemble, and can be used in single-, double-, and triple-axis tests. The accuracy and reliability of the test system were verified through its application in the uniaxial compression test of a fractured body under the action of stable hydraulic pressure. The test system provides the foundation for the study of the physical mechanisms of deep underground rock masses subjected to long-term, stable seepage pressure.

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Laboratory Investigations on the Hydraulic Fracturing of Granite Cores

Cited by 8 publications

References 26 publications

Cyclic soft stimulation (CSS): a new fluid injection protocol and traffic light system to mitigate seismic risks of hydraulic stimulation treatments

Cyclic soft stimulation (CSS): a new fluid injection protocol and traffic light system to mitigate seismic risks of hydraulic stimulation treatments

Fault Reactivation During Fluid Pressure Oscillations: Transition From Stable to Unstable Slip

Development and Application of a Hydraulic Loading Test System That Provides Continuous and Stable Hydraulic Pressure

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