There is growing fear that world oil reserves are depleting fast due to the current energy
demand, and future energy needs. Recently, there has been a call for radical shifts in
investment towards cleaner and more efficient energy technologies. However, most of
these renewable energy alternatives are still at infant stages of research. Thus, the more
conventional hydrocarbon oil is still the most logical option. Oil recovery efficiency is
heavily influenced by the structure of void space that oil occupies within the reservoir
rocks. In general, less than 50 % of oil is recoverable from the source rock, and thus the
understanding of oil entrapment (bound volume index) is essential in prediction of
economical potential of an oil reservoir. The bound volume index is the non-movable fluid
volume in oil reservoirs. Reservoir rocks are chemically and geometrically heterogeneous.
In this study, model catalyst support pellets with similar chemical and geometrical
properties to oil reservoir rocks, but with more homogeneous chemistry were investigated.
In this thesis, novel multi-technique approaches have been used to understand the transport
relationships in porous media. The mechanisms of entrapment and distribution of the
irreducible non-wetting phase within porous media was investigated with mercury
porosimetry. Mercury entrapment is strongly dependent on the structural (voidage fraction,
pore size, and pore size distribution) as well as on topological (connectivity and tortuosity)
properties of porous media. The pore size distribution (PSD), a measure of pore length, and
pore connectivity were determined by gas sorption. PGSE NMR was used to study the
heterogeneity and tortuosity of the samples. In addition, PSGE NMR was used to study the
kinetics of adsorption in porous media, and thus elucidate the relationships of liquid
connectivity, and molecular exchange between liquid and vapour phases.
In general, mercury entrapment occurred at larger mesopore radii, and was present at all
experimental time-scales. In addition, mercury entrapment was found to increase with
increased variance in the PSD. PGSE NMR kinetic studies revealed that tortuosity
decreased with an increased liquid connectivity and there was enough evidence to suggest
molecular exchange between the liquid and vapour phases. Furthermore, the tortuosity of
fully saturated samples increased with an increased mercury entrapment.
|Date of Award||1 Apr 2011|
|Supervisor||Sean Rigby (Supervisor)|