Relation between molecular structure of smectite and liquefaction of mudstone

In carbon storage activities, and in shale oil and gas extraction (SOGE) with carbon dioxide (CO2) as stimulation fluid, CO2 comes into contact with shale rock and its pore fluid. As a reactive fluid, the injected CO2 displays a large potential to modify the shale’s chemical, physical, and mechanical properties, which need to be well studied and documented. The state of the art on shale–CO2 interactions published in several review articles does not exhaust all aspects of these interactions, such as changes in the mechanical, petrophysical, or petrochemical properties of shales. This review paper presents a characterization of shale rocks and reviews their possible interaction mechanisms with different phases of CO2. The effects of these interactions on petrophysical, chemical and mechanical properties are highlighted. In addition, a novel experimental approach is presented, developed and used by our team to investigate mechanical properties by exposing shale to different saturation fluids under controlled temperatures and pressures, without modifying the test exposure conditions prior to mechanical and acoustic measurements. This paper also underlines the major knowledge gaps that need to be filled in order to improve the safety and efficiency of SOGE and CO2 storage.

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“…Almost no ionic replacement occurs at either the tetrahedral or the octahedral sheets in kaolinite. [38].…”

Section: Mineralogical Properties Of Shalesmentioning

confidence: 99%

Micro- and Macroscale Consequences of Interactions between CO2 and Shale Rocks

et al. 2020

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“…The interlayer distance between particles increases linearly with the increase of water; therefore, when one layer of water molecules is added, the interlayer space is increased by 2.8~3.1 Å During the process of water absorption by montmorillonite, the increased distance between the particles occurs with respect to the increase in the interlayer of water molecules at mutual contact positions. The interlayer distance between particles increases linearly with the increase of water; therefore, when one layer of water molecules is added, the interlayer space is increased by 2.8~3.1 Å [1,34,38]. Thus, the distance between montmorillonite particles increases linearly with an increase in water and the force between particles can be expressed by the water content as shown in Equation 4:…”

Section: Hydration Weakening Modelmentioning

confidence: 99%

“…Advances made to understand the behaviour of mudstone over the last 50 years have shown the importance of the role of clay mineral components when modelling its behaviour. In the field of geotechnical and hydraulic engineering, soil and rock comprised of montmorillonite have an adverse effect on the stability of engineering structures owing to the layered molecular structure of montmorillonite and its hydration swelling and weakening properties [1][2][3].…”

Section: Introductionmentioning

confidence: 99%

Modelling Hydration Swelling and Weakening of Montmorillonite Particles in Mudstone

Sun

et al. 2019

Processes

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It is of paramount importance to understand the hydration swelling and weakening properties of clay minerals, such as montmorillonite, to determine their mechanical responses during deep underground argillaceous engineering. In this study, the mineral components and microscopic structure of mudstone were characterised using X-ray powder diffraction and field-emission scanning electron microscopy. Experimental schemes were devised to determine the properties of mudstone under the influence of underground water and stress; these involved compacting montmorillonite particles with various water contents and conducting uniaxial compression tests. Experimental results demonstrated that compaction stress changes the microscopic structure of the montmorillonite matrix and affects its properties, and stress independency was found at particular water and stress conditions. Two equations were then obtained to describe the swelling and weakening properties of the montmorillonite matrix based on the discrete element method; further, the hydration swelling equation represents the linear decrease in the density of the montmorillonite matrix with an increase in the water content. It was also determined that the water dependency of uniaxial compressive strength can be described by negative quartic equations, and the uniaxial compressive strength of the montmorillonite matrix is just 0.04 MPa with a water content of 0.6. The experimental results are in good agreement with the calculated solutions and provide an important experimental basis to the understanding of the mechanical properties of montmorillonite-rich mudstones under the influence of underground water and stress.

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“…This structure easily absorbs the environmental water and then swells 12,13 . Besides, the MMT crystal presents the highest cation exchange capacity compared to other clay minerals 10,14 . High-temperature treatment is a popular approach to modify MMT by increasing adsorption 15 .…”

Section: Introductionmentioning

confidence: 98%

“…The shear failure of muddy intercalation under the water function is mainly due to the clay minerals swelling and softening [5][6][7] . The clay minerals take account for 60% of muddy intercalation 2,3,8 , and among which the montmorillonite (MMT) presents the worst water resistance 9,10 . Therefore, ameliorating MMT properties probably reinforces muddy intercalation to prevent structural failure from heavy rainfall or high groundwater content.…”

Section: Introductionmentioning

confidence: 99%

Micro-mechanism of Shear Strength and Water Stability Enhancement of Montmorillonite by Microwave Heating

Qiu

et al. 2022

Mat. Res.

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Microwave heating potentially reinforces the muddy intercalation to eliminate slope failure. Montmorillonite has the worst water resistance among the muddy intercalation components, which is a primary facet of inducing muddy intercalation failure. This study investigates the mechanism of shear strength and water stability enhancement of montmorillonite heated by the microwave oven and muffle furnace from room temperature to 800 °C. Results show that montmorillonite mineralogical evolution can be divided into three stages: room temperature-300 °C, 300-600 °C, and 600-800 °C. Microwave heating is more efficient in montmorillonite heat treatment than muffle furnace heating and makes the montmorillonite dehydroxylated earlier. It is worth noting that hot spots formed inside the montmorillonite specimens during the microwave heat treatment. Microwave significantly promotes the shear resistance of montmorillonite, where the maximum increases are 39.94% of cohesion at 600 °C and 20.54% of internal friction angle at 700 °C. This enhancement is due to the rough surfaces and large particles produced by dehydroxylation and Mg-Al spinel synthesis, and the significant degree of disorder state of MMT after dehydroxylation also plays a vital role. The microwave-heated montmorillonite over 500 °C presents good integrity in the water immersion test over 24 h. Considering the shear behavior and water stability, we believe the most reasonable heating interval for microwaves is 500-600°C.

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Relation between molecular structure of smectite and liquefaction of mudstone

Abstract: As the degrees of water soaking increase, breakage of the smectite microstructure will occur, and overall energy of the mode will dramatically decreases, resulting in mudstone with macroscopic phenomena such as argillization and liquefaction.

Cited by 12 publications

References 18 publications

Micro- and Macroscale Consequences of Interactions between CO2 and Shale Rocks

Micro- and Macroscale Consequences of Interactions between CO2 and Shale Rocks

Modelling Hydration Swelling and Weakening of Montmorillonite Particles in Mudstone

Micro-mechanism of Shear Strength and Water Stability Enhancement of Montmorillonite by Microwave Heating

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