Elastic, viscoelastic, and strength properties of Marcellus Shale specimens

Kamali-Asl, Arash; Ghazanfari, Ehsan; Newell, Pania; Stevens, Mathew

doi:10.1016/j.petrol.2018.05.074

Cited by 43 publications

(10 citation statements)

References 38 publications

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“…Note that all fractions are given in vol%, which is more relevant for mechanical properties than wt% (for conversion see Rybacki et al, 2015). The composition of shales is estimated from data provided by Wang and Carr (2012), Sone and Zoback (2013), Gasparik et al (2014b), Rybacki et al (2015), Lora et al (2016), Herrmann et al (2018), and Kamali-Asl et al (2018.…”

Section: Discussionmentioning

confidence: 99%

The Furongian to Lower Ordovician Alum Shale Formation in conventional and unconventional petroleum systems in the Baltic Basin – A review

Schulz

Yang

Schovsbo

et al. 2021

Earth-Science Reviews

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The organic carbon-and uranium-rich, marine Alum Shale Formation Formation in northwestern Europe (Middle Cambrian, Miaolingian to Early Ordovician) was deposited in the Baltic Basin and surrounding areas. It is a proven source rock for conventional oil either in sandstones of Cambrian age or Ordovician and Silurian carbonates, and also contains a potential for shale oil and for biogenic or thermogenic shale gas. compared to other well-studied shale formations. Based on brittleness estimates, the Alum Shale Formation may be regarded as an unconventional reservoir rock of medium quality from the mechanical point of view.

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Section: Discussionmentioning

confidence: 99%

The Furongian to Lower Ordovician Alum Shale Formation in conventional and unconventional petroleum systems in the Baltic Basin – A review

Schulz

Yang

Schovsbo

et al. 2021

Earth-Science Reviews

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“…Carbonate and quartz are the stiffest minerals in shale rocks, while clay minerals and organic matter are softer. Therefore, it would be reasonable to assume that an increase in "clay+TOC" content would result in lower bulk modulus values (i.e., higher pressure dependency of mechanical deformation) [31]. This might not be the case when minor mineralogical differences exist, although, it certainly holds as the difference becomes more significant.…”

Section: Pressure-dependencymentioning

confidence: 99%

Effects of Supercritical CO2 on Matrix Permeability of Unconventional Formations

2021

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We studied the effects of supercritical carbon dioxide (scCO2) on the matrix permeability of reservoir rocks from the Eagle Ford, Utica, and Wolfcamp formations. We measured permeability using argon before exposure of the samples to scCO2 over time periods ranging from days to weeks. We measured permeability (and the change of permeability with confining pressure) when both argon and scCO2 were the pore fluids. In all three formations, we generally observe a negative correlation between initial permeability and carbonate content – the higher the carbonate content, the lower the initial permeability. In clay- and organic-rich samples, swelling of the matrix resulting from adsorption decreased the permeability by about 50% when the pore fluid was scCO2 although this permeability change is largely reversible. In carbonate-rich samples, dissolution of carbonate minerals by carbonic acid irreversibly increased matrix permeability, in some cases by more than one order of magnitude. This dissolution also increases the pressure dependence of permeability apparently due to enhanced mechanical compaction. Despite these trends, we observed no general correlation between mineralogy and the magnitude of the change in permeability with argon before and after exposure to scCO2. Flow of scCO2 through mm-scale cracks appears to play an important role in determining matrix permeability and the pressure dependence of permeability. Extended permeability measurements show that while adsorption is nearly instantaneous and reversible, dissolution is time-dependent, probably owing to reaction kinetics. Our results indicate that the composition and microstructure of matrix flow pathways control both the initial permeability and how permeability changes after interaction with scCO2. Electron microscopy images with Back-Scattered Electron (BSE) and Energy Dispersive Spectroscopy (EDS) revealed dissolution and etching of calcite minerals and precipitation of calcium sulfide resulting from exposure to scCO2.

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“…The stress lag is normally noticed in the viscoelasticity medium. With a large content of clay, clay shale can be treated as the viscoelasticity medium (Arash et al 2018). Due to the property of viscoelasticity, stress inside rock normally lags behind stress outside rock, creating lag stress between stress inside and outside of core sample, as shown in Fig.…”

Section: Influence Of Unloading Rangementioning

confidence: 99%

Investigation on influence of drilling unloading on wellbore stability in clay shale formation

2020

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Wellbore collapse frequently happens in the clay shale formation. To maintain wellbore stability, appropriate mud pressure is a vital factor. When clay formation is opened, drilling unloading occurs, modifying rock structure and strength at the wall of borehole, which affects the selection of mud pressure. Currently, mechanism of drilling unloading is still poorly understood which in return will bring a concern to wellbore stability. Therefore, in this study, a combination of triaxial compressive test and ultrasonic wave test has been used to simulate drilling unloading and analyze its mechanism. Results indicate that more void space is created inside the clay shale sample due to unloading. This structure change leads to a decline of strength and acoustic amplitude. Additionally, unloading influence is depended on varying drilling unloading parameters. Small unloading range and fast unloading rate are able to enhance stability. With various degrees of unloading impact, collapse pressure equivalent density has a clear modification, proving that unloading is a non-negligible influencing factor of wellbore stability. Besides, the unloading effect is much stronger in large confining pressure, implying that more attention should be given to unloading when drilling is in extreme deep or high geostress formation. Findings in this paper can offer theoretical guidance for drilling in the clay shale formation.

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Elastic, viscoelastic, and strength properties of Marcellus Shale specimens

Cited by 43 publications

References 38 publications

The Furongian to Lower Ordovician Alum Shale Formation in conventional and unconventional petroleum systems in the Baltic Basin – A review

The Furongian to Lower Ordovician Alum Shale Formation in conventional and unconventional petroleum systems in the Baltic Basin – A review

Effects of Supercritical CO2 on Matrix Permeability of Unconventional Formations

Investigation on influence of drilling unloading on wellbore stability in clay shale formation

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