Damage effects and mechanisms in granite treated with acidic chemical solutions

Miao, Shu; Cai, Meifeng; Guo, Qiang; Wang, Peitao; Liang, Mingchun

doi:10.1016/j.ijrmms.2016.07.002

Cited by 85 publications

(44 citation statements)

References 17 publications

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“…The high clay content visible on SCCL in association with high calcite content or the high fracture density can explain the low Young's modulus of hydrothermally altered zones as the Young's modulus for clay mineral is very low (6.2 GPa for dickite; Prasad et al, ) compared to those of the minerals found in the fresh granite (see Table ). Miao et al () indicate a strong decrease of young's modulus for chemically altered granite specimen in the laboratory. Meller, Kontny, et al () also showed a clear correlation between hydrothermal alteration characterized by high SCCL and low values of magnetic susceptibility.…”

Section: Synthesis Of Results With Complementary Calcimetry Investigamentioning

confidence: 99%

“…If one considers the amount of each mineral type and its Young's modulus, a simple calculation provides a mean Young's modulus of 80.5 GPa for the fresh standard Soultz granite, which corresponds to that commonly observed for fresh granite (Miao et al, 2016). The Young's modulus of calcite is 84 GPa (Lama & Vutukuri, 1978), which is very close to that calculated for the fresh granite.…”

Section: Synthesis Of Results With Complementary Calcimetry Investigamentioning

confidence: 99%

See 1 more Smart Citation

Is There a Link Between Mineralogy, Petrophysics, and the Hydraulic and Seismic Behaviors of the Soultz‐sous‐Forêts Granite During Stimulation? A Review and Reinterpretation of Petro‐Hydromechanical Data Toward a Better Understanding of Induced Seismicity and Fluid Flow

Meller

Ledésert

2017

JGR Solid Earth

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In the framework of the European Soultz‐sous‐Forêts enhanced geothermal system (EGS) in Alsace, France, 20 years of scientific and preindustrial tests had to be performed before the site began production of electricity in 2008. Stimulation tests were designed to enhance the permeability because most of the numerous natural fractures that crosscut the granite body were sealed by secondary minerals that crystallized as an effect of the circulation of local hot brines. The deep‐seated granitic reservoir is located between 4,500 and 5,000 m depths. Hydraulic stimulations were conducted in the four deep wells (GPK1, GPK2, GPK3, and GPK4) inducing different microseismic event patterns, which cannot be explained by tectonic structures alone. In the present work, we provide a review of the hydraulic tests and reinterpret them in the light of mineralogical data obtained along the boreholes. A clear relationship appears between mineralogy (mainly clay and calcite content) and the petrophysical, mechanical, and hydraulic behaviors of the rock mass. High calcite contents are correlated with an abundance of clay minerals, low Young's modulus, low magnetic susceptibility, and variation in spectral gamma ray. Microearthquakes are generated in the fresh granite zones, while clay and calcite‐rich zones, linked with hydrothermal alteration, might behave aseismically during hydraulic stimulations. These findings highlight the importance of a detailed knowledge of the petrography of a reservoir to conduct an effective stimulation while keeping the seismic hazard at a minimum.

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Section: Synthesis Of Results With Complementary Calcimetry Investigamentioning

confidence: 99%

Section: Synthesis Of Results With Complementary Calcimetry Investigamentioning

confidence: 99%

Is There a Link Between Mineralogy, Petrophysics, and the Hydraulic and Seismic Behaviors of the Soultz‐sous‐Forêts Granite During Stimulation? A Review and Reinterpretation of Petro‐Hydromechanical Data Toward a Better Understanding of Induced Seismicity and Fluid Flow

Meller

Ledésert

2017

JGR Solid Earth

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“…Massive efforts have been made to explore the water-induced changes in rock properties [1][2][3][4][5][6][14][15][16][17][18][19][20][21][22][23][24][25][26][27][28]. Among them, the effects of water on the uniaxial compressive behavior, such as the uniaxial compressive strength (UCS) and elastic modulus, are more commonly studied than other mechanical parameters due to their most direct, practical relevance to rock engineering applications [7].…”

Section: Introductionmentioning

confidence: 99%

“…Among them, the effects of water on the uniaxial compressive behavior, such as the uniaxial compressive strength (UCS) and elastic modulus, are more commonly studied than other mechanical parameters due to their most direct, practical relevance to rock engineering applications [7]. Over several decades, uniaxial compression tests have been conducted on a large variety of rock types under different moisture conditions, involving igneous rocks [25,26], sedimentary rocks [1,3,4,[14][15][16]27,28] and metamorphic rocks [2,29,30]. For instance, Dyke and Dobereiner [15] in 1991 reported that an increase in water content tends to reduce rock strength.…”

Section: Introductionmentioning

confidence: 99%

Water-Weakening Effects on the Mechanical Behavior of Different Rock Types: Phenomena and Mechanisms

et al. 2019

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The presence of water strongly affects rock properties and would be related to a series of geological disasters. To understand water saturation effects on the mechanical behavior of different rock types and interpret the underlying mechanisms of differences in water sensitivity, three kinds of rocks, namely sandstone, granite and marble, were selected for tests. Uniaxial compression experiments were conducted on specimens under oven-dried and water-saturated conditions. Acoustic emission (AE) techniques were also applied to monitor and record AE signals during tests. Experimental results reveal that water weakens the mechanical parameters of the three tested rocks, such as uniaxial compressive strength (UCS), elastic modulus and critical strain. The sandstone undergoes the greatest weakening with the addition of pore water, the mechanical properties of the granite exhibit relatively minor reductions, while the marble is the least affected by water saturation. The water-weakening degree of rock properties depends on the porosity as well as the mineralogy, especially the proportion of quartz and swelling clays. Moreover, after water saturation, the failure pattern of the sandstone and the granite tends to transform into the shear-dominant mode from the tensile one in dry state, probably due to frictional reduction. However, the water presence does not change the failure mode of the marble.

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“…Some scholars carried out experimental studies on the triaxial mechanical behavior of granite after chemical erosion [11][12][13][14]. The effects of chemical solutions with different pH values on the strength and deformation of granite were discussed, and the corrosion mechanism of granite by chemical solution was also analyzed.…”

Section: Introductionmentioning

confidence: 99%

Creep Strain and Permeability Evolution in Cracked Granite Subjected to Triaxial Stress and Reactive Flow

Zhang

Zhao

et al. 2018

Geofluids

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Fluid flow and fluid-rock interaction mainly take place in fracture network, consequently resulting in deformation and permeability variation of rock and deterioration of the wellbore performance. Mechanical-reactive flow coupling creep tests are performed on cracked granite under various confining pressures and acid and alkaline solution flows. The testing results show that the confining pressure and solution pH significantly influence the creep deformation, creep strain rate, and permeability. A primary creep stage and secondary creep stage are observed in all creep tests in this study; notably, the sample under a confining pressure of 10 MPa and acid solution injection undergoes creep failure for over 2700 hours. The acid solution has a more obvious influence on the creep behavior than that of the alkaline solution. With an increase in confining pressure, the total creep strain and creep strain rate in the samples gradually decrease during the injection of either solution. The permeability of the samples injected with either solution gradually deceases during the testing process, and this deceasing rate increases with the confining pressure. The scanning electron microscopy observations on the crack surfaces after the creep tests show that the surfaces of the fractures injected with the acid solution are smooth due to the dissolution of the matrix, while those injected with the alkaline solution include voids due to the dissolution of quartz. These experimental results could improve the understanding of the long-term transport and mechanical behaviors of wellbore.

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Damage effects and mechanisms in granite treated with acidic chemical solutions

Cited by 85 publications

References 17 publications

Is There a Link Between Mineralogy, Petrophysics, and the Hydraulic and Seismic Behaviors of the Soultz‐sous‐Forêts Granite During Stimulation? A Review and Reinterpretation of Petro‐Hydromechanical Data Toward a Better Understanding of Induced Seismicity and Fluid Flow

Is There a Link Between Mineralogy, Petrophysics, and the Hydraulic and Seismic Behaviors of the Soultz‐sous‐Forêts Granite During Stimulation? A Review and Reinterpretation of Petro‐Hydromechanical Data Toward a Better Understanding of Induced Seismicity and Fluid Flow

Water-Weakening Effects on the Mechanical Behavior of Different Rock Types: Phenomena and Mechanisms

Creep Strain and Permeability Evolution in Cracked Granite Subjected to Triaxial Stress and Reactive Flow

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