Time-lapse nanometre-scale 3D synchrotron imaging and image-based modelling of the response of shales to heating
9
Citation
95
Reference
10
Related Paper
Citation Trend
Abstract:
The development of pore and fracture networks at the nano-scale as a response to heating can reveal coupled physical relationships relevant to several energy applications. A combination of time-lapse 3D imaging and finite-element modelling (FEM) was performed on two typical thermally immature shale samples, Kimmeridge Clay and Akrabou shale, to investigate thermal response at the nm-scale for the first time. Samples were imaged using Transmission X-ray Microscopy (TXM) with a voxel resolution of 34 nm at the I13–2 beamline at Diamond Light source, UK. Images were taken after heating to temperatures of 20 °C, 300 °C, 350 °C and 400 °C. The initiation of nano-pores within individual minerals and organic matter particles were observed and quantified alongside the evolution from nano-pores to micro-fractures. The major expansion of pore-volume occurred between 300 and 350 °C in both samples, with the pores elongating rapidly along the organic-rich bedding. The internal pressures induced by organic matter transformation influenced the development of microfractures. Mechanical properties and strain distributions within these two samples were modelled under a range of axial stresses using FEM. The results show that the overall stiffness of the shale reduced during heating, despite organic matter becoming stiffer. The varied roles of ductile (e.g., clay minerals, organic matter) and brittle materials (e.g., calcite, pyrite) within the rock matrix are also modelled and discussed. The configurations of organic matter, mineral components, porosity and connectivity impact elastic deformation during shale pyrolysis. This work extends our understanding of dynamic coupled processes of microstructure and elastic deformation in shales to the nm-scale, which also has applications to other subsurface energy systems such as carbon sequestration, geothermal and nuclear waste disposal.Keywords:
Micromechanics
Micromechanics
Eigenstrain
Peridynamics
Multiscale Modeling
Cite
Citations (3)
Micromechanics
Representative elementary volume
Basis (linear algebra)
Cite
Citations (0)
The compressibility of calcite to 40 kbar has been remeasured by using a piston-cylinder apparatus. Calcite 1 is found to transform to calcite 2 at 14.5 kbar with a volume change of 0.00483 cm3/g, and calcite 2 is found to change to calcite 3 at 17.4 kbar with a volume change of 0.01291 cm3/g. The volume compression data for the three phases are described by the following quadratic relations: Calcite 1 Calcite 2 Calcite 3 where P is pressure in kilobars. The compression data for calcite 1 and calcite 3 are in good agreement with those available in the literature. The data exhibiting an abnormally high compression of calcite 2 have been reported for the first time. The compression data for calcite 2 have been used to explain quantitatively the abnormal drop near 15 kbar observed in the ultrasonic sound velocity in calcite.
Cite
Citations (113)
Micromechanics
Cite
Citations (5,404)
The application of finite element simulation method of micromechanics in the field of multi-phase materials is promoted by the extensive use of multi-phase materials and the development of computer technology.The application status of finite element simulation of micromechanics in multi-phase materials is introduced.The 2D and 3Dfinite element calculation methods of micromechanics are summarized.Some major achievements obtained by adopting finite element simulation of micromechanics in the research of composites and steel materials are highlighted.Currently,the application of finite element simulation of micromechanics in the field of multi-phase steels is relatively less,thus the research and development related to it are briefly reviewed and envisaged.
Micromechanics
Cite
Citations (1)
Cite
Citations (193)
A 3D incremental sectional micromechanics model is developed for strain rate dependent inelastic polymer matrix composite materials. A repeating unit cell is identified within the material system, which is then divided into several subcells. Uniform stress and uniform strain assumptions are applied in each subcell. Appropriate stress and strain continuity assumptions are made between subcells. A two-level approach is developed for solving the system of equations of the micromechanics model in order to improve the computational efficiency. The developed micromechanics model is implemented into a commercial finite element analysis package. The results show that the current 3D micromechanics model can address the rate dependent inelastic behavior of polymer composite materials accurately and efficiently. Numerical results are also presented to demonstrate the applicability of the micromechanics theory in modeling high velocity impact of composite laminates. Good correlation is observed with experimental observation.
Micromechanics
Matrix (chemical analysis)
Cite
Citations (10)
Micromechanics
Cite
Citations (1)
ABSTRACT Cultures of known species of fungi placed on crystals of Iceland spar calcite resulted in extensive dissolution of the calcite. This organically mediated dissolution produced large patches of spiky calcite within a period of 253 days. The dissolution of the calcite occurred via surface-reaction-controlled kinetic processes that were mediated by the fungi. This occurred despite the lack of vast quantities of fluids undersaturated with respect to calcite. Locally, at least 10 µm of calcite was removed from the original crystal surface.
Cite
Citations (33)
ABSTRACT Mineralogical analysis of calcite and Mg‐calcite by X‐ray diffraction requires that the samples be ground to a powder. Such grinding determines the particle size of the powder and the structural damage of the minerals. Both of these in turn affect the peak intensities recorded by the X‐ray machine. Most carbonate sediments are inhomogeneous; they contain both calcite and Mg‐calcite which are affected differently by grinding. Such differences cause quantitative analytical results to be inconsistent with the true mineralogical abundance. The two acceptable methods of analysis—(1) measurement of peak height from the base and (2) measurement of the area under the peak—were compared to determine if sample preparation affects the quantitative results. In samples with variable and relatively small amounts of calcite and Mg‐calcite the measurement of peak height yields more reproducible results than does the measurement of peak areas. Different proportions of particle size of the mineralogical components in a sample powder, affect proportionally more the peak areas than the peak heights. Extensive grinding causes structural damage of the component minerals which affects much more the peak areas than the peak heights. Thus for quantitative analyses of calcite and Mg‐calcite in inhomogeneous carbonate samples which require differing grinding times and have greatly variable amounts of calcite and Mg‐calcite, the peak height measurement seems to be a better method than peak area measurement.
Cite
Citations (37)