Quality Evaluation of Epoxy Pore Casts Using Silicon Micromodels: Application to Confocal Imaging of Carbonate Samples

Abstract

Pore casting refers to filling the void spaces of porous materials with an extraneous fluid, usually epoxy resin, to obtain a high-strength composite material, stabilize a fragile porous structure, produce a three-dimensional replica of the pore space, or provide imaging contrast. Epoxy pore casting may be accompanied by additional procedures, such as etching, in which the material matrix is dissolved, leaving a clean cast. Moreover, an epoxy resin may be mixed with fluorophore substances to allow fluorescence imaging. Our work aims to investigate and optimize the epoxy pore casting procedure parameters, for example, impregnation pressure. We use silicon micromodels as a reference to validate the key parameters of high-pressure resin impregnation. We demonstrate possible artifacts and defects that might develop during impregnation with resin, e.g., resin shrinkage and gas trapping. In the end, we developed an optimized protocol to produce high-quality resin pore casts for high-resolution 3D imaging and the description of microporosity in micritic carbonates. In our applications, the high-quality pore casts were acid-etched to remove the non-transparent carbonate material, making the pore casts suitable for imaging with Confocal Laser Scanning Microscopy (CLSM). In addition, we evaluate the quality of our etching procedure using micro-computed tomography (micro-CT) scans of the pre- and post-etched samples and demonstrate that the etched epoxy pore casts represent the pore space of microporous carbonate rock samples with high fidelity.

Experimental and Theoretical Studies toward Superior Anti-corrosive Nanocomposite Coatings of Aminosilane Wrapped Layer-by-Layer Graphene Oxide@MXene/Waterborne Epoxy

“…The PE fracture surface is microporous with appearance of pits, while the nanocomposite fracture surface is rough with fewer tubers and pits because of dispersed silane wrapped nanofillers in the polymer matrix. The defects within the PE structure are created due to solvent evaporation and tensile stresses developed in the coating during the curing shrinkage. , Although some agglomerations are seen in the fracture surface of epoxy/F-MXene and epoxy/F-GO, the F-GO@MXene nanohybrid is inserted into the matrix with no agglomeration. The results confirm that the combination of GO and MXene as a nanohybrid could lead to uniform nanosheet dispersion quality, and there would be an enhanced adhesion and compatibility at the epoxy/F-GO@MXene interfaces.…”

Multimodal Carbonates: Distribution of Oil Saturation in the Microporous Regions of Arab Formations

“…If the buoyancy force was sufficient for the oil ganglia to overcome the capillary entry pressure to the microporous grains, the initial pore-filling brine was drained, and these grains were saturated with oil to the extent that it is quantified later using the petrophysical description published in Appendix A3 in Clerke et al [24]. Figure 2 shows SEM images of the etched epoxy pore cast of an Arab-D sample, illustrating the shape of each microporosity type [29,30].…”

“…We used high-resolution SEM images of carbonates pore casts of Arab-D samples to identify microporosity types summarized in Table 1 [29,30]. The rock samples were impregnated by epoxy in two stages: vacuum impregnation in a desiccator, followed by high-pressure (up to 1000 psi) impregnation.…”