Mehrdad Pasha

Pore Volume Analysis of Gas Shale Samples Using 3-D X-ray Micro Tomography

Understanding the porosity of gas shale is of great importance in many applications such as for enhanced recovery in gas reservoir. The first step for understanding the above properties is the precise quantification of the structure of the porous media. The structure may be characterised using traditional surface area measurement or mercury porosimetry for pore size analysis. However, these methods would provide data rather on pore sizes rather than their structures and configuration within low permeable samples. Modern 3D and non-destructive imaging techniques such as x-ray microtomography (XMT) provides a more convenient and intuitive alternative technique to scanning electron microscopy. The importance of quantitative pore structure characterization in understanding shale reservoir behaviors and lack of measurement techniques are the two main motivation factors behind this research. In this research three-dimensional x-ray micro tomography (XMT) imaging techniques were used to carry out a three-dimensional pore volume analysis of shale samples based on pores size, structure, geometry and orientation. Two samples with different properties (mainly in mercury intrusion porosity, MIP) were tested. It was found that the overall micro porosity obtained from XMT is about 0.7% and 0.3% for sample 1 and 2 respectively and significantly less than those of MIP. Both samples have very close structure orientation and geometry of the pores.

Analysis of seed processing by the distinct element method

The undesirable breakage of seeds during processing may result in quality degradation. Seeds experience a portfolio of shear and impact stresses as they flow through various machinery, and this may cause surface damage as well as integral damage. An in-depth study and understanding of the microscopic mechanisms of the various processes is needed to investigate and address the problem of breakage. The main aim of this work is to carry out a parametric study of the effect of sliding and rolling friction on the flow field of seeds in a seed coater device by modeling particles motion using Distinct Element Method (DEM). It was found that sliding friction plays an important role in changing the flow pattern and particles solid fraction in a specified measurement cell. However, study of particle rolling friction showed that flow pattern and solid fraction of particles will not be affected once the coefficient of rolling friction exceeds a value of 0.1.

Biomimetically reinforced transparent nanostructures fabricated by pulsed laser deposition

We have recently developed a new concept of glass and polymer superlattice structures that has superior optical and mechanical properties arising from atomic scale engineering approach. The interlayers of glass and polymer can have thickness as low as 2 nm and the structures can be grown on polymer or glass substrates by pulsed laser deposition technology. A biomimetic approach was carried out to optimise the reinforcement via replicated brick and mortar and gneiss rock structures. Discrete element method and nanoindentation methods were carried out to optimize the performance of such structures.