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Herein, the effect of the addition of Ni‐coated carbon nanotubes (CNTs) on the microstructure, mechanical properties, and morphology of zirconia porous cellular structures is studied, aiming to increase their mechanical strength. Highly porous structures of monolithic zirconia (ZrO2) and zirconia reinforced with Ni‐doped CNTs (ZrO2 + CNT/Ni) are fabricated through the replica method. Scanning electron microscopy and micro‐computed tomography (microCT) analyses show that ZrO2 + CNT/Ni specimens present lower overall porosity (88.0%) than monolithic ZrO2 (93.8%), indicating improved sintering kinetics. Compressive tests for the ZrO2 + CNT/Ni samples result in a compressive strength of 0.82 ± 0.10 MPa, a threefold value of that of the monolithic sample (0.25 ± 0.07 MPa). The ZrO2 + CNT/Ni samples also present a higher elastic modulus (41.02 ± 4.94 MPa) than the ZrO2 ones (21.92 ± 5.40 MPa). Thus, the addition of Ni‐coated CNTs significantly improves the strength of highly porous zirconia cellular structures. [ABSTRACT FROM AUTHOR]

The X-ray microtomography was used to visualize and characterize the remobilization oil process inside the porous system of a carbonate rock sample. After being saturated with a brine solution, dodecane oil was injected into the porous media, initially a predominant water-wet system. After an aging process is performed, the system became mixed-wet. The remobilization was induced by the injection of two KI (Potassium Iodide) brine solutions, a high salinity solution injection (1.5 M) followed by a low one (0.3 M). The intention was to achieve, besides the immiscible displacement process, oil remobilization due to the modification of interfacial properties of fluids and wettability caused by low salinity of the injected brine. It was observed that the low salinity brine was capable of shifting the oil inside the porous medium and reduce the residual oil saturation. [ABSTRACT FROM AUTHOR]

The microstructure of a porous cellular ceramic exhibiting two spatial characteristic lengths was characterized to determine parameters of its pore space morphology and connectivity. In order to assess the hierarchical microstructure, X-ray computed micro-tomography was employed as an imaging technique to supply three-dimensional images in two spatial scales. Two samples, at different sintering temperatures, were produced by emulsification of sunflower oil in aqueous aluminum oxide suspensions using gelatin bloom 90 as the gelling agent, dodecyl sodium sulfate as the surfactant and native cassava starch as the gelling and porogenic agent. Image processing and morphological characterization were performed on each spatial scale, individually allowing the calculation of the total porosity and pore size distribution of the ceramic sample. For the numerical simulation of the intrinsic permeability, representative images of the two spatial scales were superposed in a single super-image. This simulation was performed on the 3D pore network extracted from the super-image. The simulated permeability results were interpreted on the basis of the microstructure. [ABSTRACT FROM AUTHOR]

Considerable attention has been paid to the development of unconventional reservoir fields due to the availability of such resources worldwide. The heterogeneities throughout the pore space structure in a rock and their effects on the occurrence of gas and oil can be quantitatively analysed using fractal theory. This study focuses on the investigation of the fractal dimension ( FD ) in shale and tight gas sandstones (TGS) from Brazilian oil and gas fields using 3-D X-ray nano- and micro-computed tomography. Obtaining the broad size distribution of pore space structures in unconventional reservoir rocks using 3-D images is challenging due to the multiscale characteristics of the rocks. Thus, sample images were acquired with two voxel size/resolutions (0.064 μm and from 0.46 to 1.20 μm). Very small pores (ganglia), main pore networks and organic matter grains were observed as segmented structures within sample sets for which the FD was assessed and quantified. Box-counting (BC) and pore size distribution (PSD) approaches were applied. The average FD values ranged from 1.78 to 2.59 in shale and from 2.36 to 2.46 in TGS. Correlations of the FD with the experimentally acquired specific surface area, porosity and permeability related petrophysical properties, relevant to the quantitative modelling of gas transport in unconventional reservoirs, were established. The pore scale morphologies described by the FD from 3-D X-ray CT images help on the foundation for further research in shale/tight gas sandstones. [ABSTRACT FROM AUTHOR]

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This work focuses on the characterization of the overall pore size distribution in tight gas sandstones originating from distinct Brazilian fields, as well as fluid flow circulation described by single-phase permeability. The former was achieved by the combination of nitrogen adsorption and mercury intrusion techniques and the latter estimated by empirical relations validated by the pulse-decay technique. The nature of nitrogen permeability change was investigated on tight gas core samples under a varying effective stress of 2–40 MPa, while the gas slippage was verified shifting mean pore pressures from 8.62 to 2.76 MPa in the laboratory pulse-decay. The best agreements between the estimated and measured permeabilities (from 0.00033 to 0.016 mD and from 0.0004 to 0.034 mD) reveal that obtained overall pore structure’ parameters play significant role in the results which were also supported by Field Emission Scanning Electron Microscopy (FESEM) and X-Ray Diffraction (XRD) analysis. [ABSTRACT FROM AUTHOR]