The concept of creating heterogeneous structures by nanocasting techniques from a combination of several homogeneous surfactant templated structures to model reservoir rock properties has not been approached prior to this research project, and will be used to test and provide better understanding of gas adsorption theories such as the pore blocking phenomenon (Seaton, 1991). Porous media with controlled pore sizes and geometry can be used to mimic a variety of reservoir rock structures, as it can be engineered to consist of a network of elements which, individually, could have either regular or irregular converging and diverging portions. The restrictions in these elements are called throats, and the bulges pores. Catalysts developed from a range of Nanotechnology applications could be used in down-hole catalytic upgrading of heavy oil. They could also be used as catalyst supports or to analyse the coking performance of catalysts. These studies will highlight the pore structure effects associated with capillary trapping mechanisms in rocks, and potentially allow the manipulation of transport rates of fluids within the pore structure of catalysts. Mercury-injection capillary pressure is typically favoured for geological applications such as inferring the size and sorting of pore throats. The difference between mercury injection and withdrawal curves will be used to provide information on recovery efficiency, and also to investigate pore level heterogeneity. Mercury porosimetry studies are carried out to provide a better understanding of the retraction curve and the mechanisms controlling the extrusion process and subsequently the entrapment of the non-wetting phase. The use of model porous media with controlled pore size and surface chemistry allows these two effects to be de-convolved and studied separately. The nanotechnology techniques employed mean that uncertainty regarding exact pore geometry is alleviated because tight control of pore geometry is possible. Trapping of oil and gas on a microscopic scale in a petroleum reservoir rock is affected by the geometric and topologic properties of the pores, by the properties of the fluids and by properties related to fluid-rock interaction such as wettability. Several distinct mechanisms of trapping may occur during displacement of one fluid by another in a porous media, however in strongly water-wet rocks with large aspect ratios, trapping in individual pores caused by associated restricting throats (may be/is) the most important mechanism of trapping. The results of the proposed research will be both relevant to the Irene Osagie Evbuomwan PhD. Thesis (2009) 9 oil and gas as well as the solid mineral sector for application as catalyst or catalyst supports. By providing a better understanding of the relationship between reservoir rock pore space geometry and surface chemistry on the residual oil levels, a more accurate assessment of the potential of a particular reservoir could be generated. The analysis of gas adsorption/desorption isotherms is widely used for the characterization of porous materials with regard to their surface area, pore size, pore size distribution and porosity, which is important for optimizing their use in many practical applications. Although nitrogen adsorption at liquid nitrogen temperature is considered to be the standard procedure, recent studies clearly reveal that the use of additional probe molecules (e.g. argon, butane, carbon dioxide, water, hydrogen, and hydrocarbons e.g. cyclohexane and ethane) allows not only to check for consistency, but also leads to a more comprehensive and accurate micro/mesopore size analysis of many adsorbents. Furthermore, significant progress has been achieved during recent years with regard to the understanding of the adsorption mechanism of fluids in materials with highly ordered pore structures (e.g., M41S materials, SBA-15). This has led to major improvements in the pore size analysis of nanoporous materials. However, there are still many open questions concerning the phase and sorption behaviour of fluids in more complex pore systems, such as materials of a heterogeneous nature/differing pore structures, which are of interest for practical applications in catalysis, separation, and adsorption. In order to address some of these open questions, we have performed systematic adsorption experiments on novel nanoporous materials with well defined pore structure synthesised within this research and also on commercial porous silicas. The results of this study and experiments allow understanding and separating in detail the influence of phenomena such as, pore blocking, advanced condensation and delayed condensation on adsorption hysteresis and consequently the shape of the adsorption isotherms. The consequences of these results for an accurate and comprehensive pore size analysis of nanomaterials consisting of more complex nanoporous pore networks are also investigated.

Millions of years of evolution have led to a wealth of highly adapted functional surfaces in nature. Among the most fascinating are superhydrophobic surfaces which are highly water-repellent and shed drops very easily owing to their chemical hydrophobicity combined with micropatterning. Superhydrophobic materials have attracted a lot of attention due to their practical applications as ultra-low friction surfaces for ships and pipes, water harvesters, de-humidifiers and cooling systems. At small length scales, where surface tension dominates over gravity, these surfaces show a wealth of phenomena interesting to physicists, such as directional flow, rolling, and drop bouncing. This thesis focuses on two examples of dynamic drop interactions with micropatterned surfaces and studies them by means of a lattice Boltzmann simulation approach. Inspired by recent experiments, we investigate the phenomenon of the self-propelled bouncing of coalescing droplets. On highly hydrophobic patterned surfaces drop coalescence can lead to an out-of-plane jump of the composite drop. We discuss the importance of energy dissipation to the jumping process and identify an anisotropy of the jumping ability with respect to surface features. We show that Gibbs' pinning is the source of this anisotropy and explain how it leads to the inhibition of coalescence-induced jumping. The second example we study is the novel phenomenon of pancake bouncing. Conventionally, a drop falling onto a superhydrophobic surface spreads due to its inertia, retracts due to its surface tension, and bounces off the surface. Here we explain a different pathway to bouncing that has been observed in recent experiments: A drop may spread upon impact, but leave the surface whilst still in an elongated shape. This new behaviour, which occurs transiently for certain impact and surface parameters, is due to reversible liquid imbibition into the superhydrophobic substrate. We develop a theoretical model and test it on data from experiments and simulations. The theoretical model is used to explain pancake bouncing in detail.

The objective of this study was to characterize non-wetting fluid in multi-phase systems comprising a range of fluid and porous medium properties. Synchrotron X-ray microtomography was used to obtain high-resolution, three-dimensional images of fluids in natural porous media. Images were processed to obtain quantitative measurements of fluid distribution, morphology, and interfacial area. Column-flooding experiments were conducted with four enhanced-solubilization (ES) solutions to examine their impact on entrapped organic liquid. Mobilization caused a change in organic-liquid morphology and distribution for most experiments. The effect of ES-solution flooding on fluid-fluid interfacial area was similar to that of water flooding. Organic-liquid mobilization was observed at total trapping numbers that were smaller than expected. This was attributed to pore-scale mobilization of blobs that were re-trapped prior to being eluted from the column. Pore-scale mobilization was also observed during water-flooding experiments for which trapping numbers varied over several orders of magnitude. Water-flooding and surfactant-flooding experiments were compared to investigate the impact of interfacial tension, viscosity, and fluid velocity on entrapped organic liquid. For similar total trapping numbers, flooding at larger velocities appeared to have a greater effect on the distribution of non-wetting blobs than lowering interfacial tension or increasing the viscosity of the wetting fluid. The fluid-normalized interfacial area was generally independent of the total trapping number. Finally, the impact of fluid type on the interfacial area between different pairs of non-wetting fluids was investigated during drainage and imbibition in four natural porous media. Interfacial areas were similar among all fluid pairs for a given porous medium. They were also similar for drainage and imbibition conditions. The maximum specific interfacial area (A(m)) was determined to quantify the magnitude of interfacial area associated with a given porous medium. The value of A(m) was larger for the media with smaller median grain diameters. Therefore, physical properties of the porous medium appear to have a greater influence on the magnitude of specific total interfacial area for a given saturation than fluid properties or wetting-phase history.