Micro-scale and nano-scale strain mapping techniques applied to creep of rocks

Quintanilla-Terminel, Alejandra; Zimmerman, M. E.; Kohlstedt, D. L.; Evans, Brian

doi:10.5194/se-2017-27

Cited by 3 publications

(4 citation statements)

References 7 publications

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“…This was done by performing a sequence of five triaxial stress-cycling experiments on a single, porous (20.4%) splitcylinder sample of Slochteren sandstone (cf. Spiers, 1979;Quintanilla-Terminel et al, 2017). In Experiments 1, 2, 3, and 5, we imposed increasingly larger stresses and/or axial strains, chosen to systematically explore the main stages in mean effective stress (P) versus total porosity reduction (Δφ t ) behavior typically reported in the literature (e.g., Wong & Baud, 2012), and to include the small strains relevant for producing reservoirs (ε < 1%).…”

Section: Discussionmentioning

confidence: 99%

“…In this study, we investigate the microphysical processes controlling inelastic deformation of Slochteren sandstone from the Groningen gas field, during each of the three main stages of deformation represented in Figure 1, that is, Stages 1, 2 and 3c. We adopt an approach similar to that used by Spiers (1979) and Quintanilla-Terminel et al (2017). A single split-cylinder sample, consisting of two equidimensional, halfcylinders of Slochteren sandstone (initial porosity = 20.4%; see: Figure 2a) was compressed in successive deviatoric stress-cycling experiments, performed at a confining pressure of 41 MPa, a pore pressure of 1 MPa and at 100 °C, representing the temperature at the top of the Groningen reservoir (NAM, 2013).…”

Section: Introductionmentioning

confidence: 99%

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Intergranular Clay Films Control Inelastic Deformation in the Groningen Gas Reservoir: Evidence From Split‐Cylinder Deformation Tests

et al. 2019

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Production of oil and gas from sandstone reservoirs leads to small elastic and inelastic strains in the reservoir, which may induce surface subsidence and seismicity. While the elastic component is easily described, the inelastic component, and any rate‐sensitivity thereof remain poorly understood in the relevant small strain range (≤1.0%). To address this, we performed a sequence of five stress/strain‐cycling plus strain‐marker‐imaging experiments on a single split‐cylinder sample (porosity 20.4%) of Slochteren sandstone from the seismogenic Groningen gas field. The tests were performed under in situ conditions of effective confining pressure (40 MPa) and temperature (100 °C), exploring increasingly large differential stresses (up to 75 MPa) and/or axial strains (up to 4.8%) in consecutive runs. At the small strains relevant to producing reservoirs (≤1.0%), inelastic deformation was largely accommodated by deformation of clay‐filled grain contacts. High axial strains (>1.4%) led to pervasive intragranular cracking plus intergranular slip within localized, conjugate bands. Using a simplified sandstone model, we show that the magnitude of inelastic deformation produced in our experiments at small strains (≤1.0%) and stresses relevant to the Groningen reservoir can indeed be roughly accounted for by clay film deformation. Thus, inelastic compaction of the Groningen reservoir is expected to be largely governed by clay film deformation. Compaction by this mechanism is shown to be rate insensitive on production timescales and is anticipated to halt when gas production stops. However, creep by other processes cannot be eliminated. Similar, clay‐bearing sandstone reservoirs occur widespread globally, implying a wide relevance of our results.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Intergranular Clay Films Control Inelastic Deformation in the Groningen Gas Reservoir: Evidence From Split‐Cylinder Deformation Tests

et al. 2019

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“…The latest optical, electron microscopy (Focused Ion Beam Scanning Electron Microscopy (FIB-SEM), Electron Backscatter Diffraction (EBSD), Transmission Electron Microscopy (TEM)) and microbeam analysis methods (Secondary Ion Mass Spectroscopy (SIMS), Fourier Transform Infrared (FTIR) and Raman spectroscopy, Laser Ablation Microprobe Inductively Coupled Plasma Mass Spectrometry (LAM-ICP-MS)) are also being employed to identify the microscale physical processes that accommodate deformation under different loading conditions (Fig. 6A), along with cutting-edge techniques such as grain-scale displacement/deformation analysis (Quintanilla-Terminel et al, 2017) (see Fig. 6B).…”

Section: New Directions In Compaction Researchmentioning

confidence: 99%

New approaches in experimental research on rock and fault behaviour in the Groningen gas field

Spiers

Hangx

Niemeijer

2017

Netherlands Journal of Geosciences

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This paper describes a research programme recently initiated at Utrecht University that aims to contribute new, fundamental physical understanding and quantitative descriptions of rock and fault behaviour needed to advance understanding of reservoir compaction and fault behaviour in the context of induced seismicity and subsidence in the Groningen gas field. The NAM-funded programme involves experimental rock and fault mechanics work, microscale observational studies to determine the processes that control reservoir rock deformation and fault slip, modelling and experimental work aimed at establishing upscaling rules between laboratory and field scales, and geomechanical modelling of fault rupture and earthquake generation at the reservoir scale. Here, we focus on describing the programme and its intended contribution to understanding the response of the Groningen field to gas production. The key knowledge gaps that drive the programme are discussed and the approaches employed to address them are highlighted.Some of the first results emerging from the work in progress are also reported briefly and are providing important new insights.

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“…Detailed strain measurements at the grain scale reveal that twinning occurs readily in well oriented grains (those with high Schmid factor for twinning), and that it is likely associated with a local backstress that causes hardening of twinned grains (Spiers, 1979). In addition, microscale strain mapping also indicates the existence of shear localised along grain boundaries at temperatures < 800 • C, potentially identifying grain-boundary sliding as a possible deformation mechanism (Quintanilla-Terminel et al, 2017).…”

Section: Introductionmentioning

confidence: 97%

The effects of grain size on semi-brittle flow in calcite rich rocks

Harbord¹,

Brantut²

2022

Preprint

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Grain size is in an important microstructural parameter affecting both brittle and plastic deformation processes. In the low temperature brittle regime, larger grain size materials typically have lower strength, whereas in the plastic flow regime smaller grain size materials tend to be weaker. It is not clear how grain size impacts at intermediate conditions where deformation of rock is accommodated by coupled brittle and plastic deformation processes.To investigate the role of grain size in the semi brittle regime we deformed three calcite-rich rocks, spanning 3 orders of magnitude in grainsize (0.006-2 mm). A gas medium triaxial apparatus was used at a range of confining pressures (200-800 MPa) and temperatures (20-400&#176;C), and samples were loaded at a constant axial strain rate (1&#215;10-5 s-1). Axial measurements of P-wave speed were performed during tests in order to infer the in-situ microstructural state of the sample.Nearly all tests show strain hardening behaviour after yield, typical of semi-brittle deformation, which is quantified using the hardening modulus (h = &#8706;&#963;/&#8706;&#949;). Grain size has a first order control on rock strength, with yield stress and h following a Hall-Petch type relationship at all P-T conditions. For a given temperature, h is low at low pressure (200 MPa) and accompanied by large decreases in wavespeed, and h increases at high pressure (>400 MPa) whereas velocity decreases by a smaller magnitude. This suggests that, at low temperature, strain hardening is relieved by microcracking. At constant pressure, wavespeed decreases significantly at 20&#176;C with progressive deformation, but remains nearly constant at 400&#176;C indicating a transition from dominatly brittle to fully plastic deformation with increasing temperature, in some cases with little change in the macroscopic strength.Given that both strength and strain hardening behaviour depend on grain size, our data suggests that grain size dynamically impacts the long term rheology of the crust. Larger grain sizes will broaden the depth distribution of the brittle ductile transition and result in a weaker peak crustal strength.

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Micro-scale and nano-scale strain mapping techniques applied to creep of rocks

Cited by 3 publications

References 7 publications

Intergranular Clay Films Control Inelastic Deformation in the Groningen Gas Reservoir: Evidence From Split‐Cylinder Deformation Tests

Intergranular Clay Films Control Inelastic Deformation in the Groningen Gas Reservoir: Evidence From Split‐Cylinder Deformation Tests

New approaches in experimental research on rock and fault behaviour in the Groningen gas field

The effects of grain size on semi-brittle flow in calcite rich rocks

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