|dc.description.abstract||The study of multiphase flow in porous media is highly relevant to many problems of
great scientific importance, such as CO2 storage and enhanced oil recovery. Even
though significant progress has been made in these areas, many challenges still
remain. For instance, the leakage of stored CO2 may occur due to the capillary
trapping failure of cap rock. Approximately 70% of oil cannot be easily recovered
from underground, because the oil is held in tight porous rocks. Although CO2
storage and enhanced oil recovery are engineering processes at a geological scale,
they are predominantly controlled by the transport and displacement of CO2 and
reservoir fluids in aquifers and reservoirs, which are further controlled by wetting
and fluid properties at pore scale. This work focuses on experimental investigations
of pore-scale wetting and displacement of fluids and CO2 in porous core samples.
Pore wetting, which has been measured based on contact angle, is a principal control
on multiphase flow through porous media. However, contact angle measurement on
other than flat surfaces still remains a challenge. In order to indicate the wetting in a
small pore, a new pore contact angle measurement technique is developed in this
study to directly measure the contact angles of fluids and CO2 in micron-sized pores.
The equilibrium and dynamic contact angles of various liquids are directly measured
in single glass capillaries, by studying the effects of surface tension, viscosity and
chemical structure. The pore contact angles are compared with the contact angles on
a planar substrate. The pore contact angle of a confined liquid in a glass capillary
differs from the contact angle measured on a flat glass surface in an open space.
Surface tension is not the only dominant factor affecting contact angle. The static
contact angle in a glass pore also varies with liquid chemical structure. Viscosity and
surface tension can significantly affect the dynamic pore contact angle. A new
empirical correlation is developed based on our experimental data to describe
dynamic pore wetting.
The CO2-fluid contact angle in porous media is an important factor affecting the
feasibility of long-term permanent CO2 storage. It determines CO2 flow and
distribution in reservoirs or aquifers, and thus ultimately finally the storage capacity.
CO2-fluid contact angles were measured in small water-wet pores and oil-wet pores,
investigating the effect of CO2 phase (gas/liquid/supercritical). The CO2 phase
significantly affects the CO2-fluid contact angle in an oil-wet pore. Supercritical
CO2-fluid contact angles are larger than gas CO2-fluid contact angles, but are smaller
than liquid CO2-fluid contact angles. However, this significant CO2 phase effect on
contact angle was not observed in a water-wet pore.
Another key issue considered in this study is two-phase flow displacement in porous
media. This strongly relates to the important macroscopic parameters for multiphase
flow transport in porous media, such as capillary pressure and relative permeability.
Here CO2-water displacements are studied by conducting CO2 flooding experiments
in a sandstone core sample, considering the effects of CO2 phase, pressure and CO2
injection rate. The capillary pressure-saturation curve, water production behaviour
and relative permeability are investigated for gas CO2-water, liquid CO2-water and
supercritical CO2-water displacements in porous media. The pressure-dependant
drainage capillary pressures are obtained as a result of CO2-water interfacial tension.
Various water production behaviours are obtained for gas CO2-water and liquid
CO2-water displacements, mainly due to the effect of CO2 dissolution. The
significant irregular capillary pressure-saturation curves and water production
behaviors can be observed for the supercritical CO2-water displacements. The water
and CO2 relative permeabilities for CO2-water displacements in a porous media are
|dc.publisher||The University of Edinburgh||en
|dc.relation.hasversion||Li, X., Fan, X., 2015. Effect of CO2 Phase on Contact Angle in Oil-wet and Water-wet Pores. International Journal of Greenhouse Gas Control, 36, 106-113.||en
|dc.relation.hasversion||Li, X., Fan, X., Brandani, S., 2014. Difference in Pore Wetting and the Wetting Measured on a Flat Surface and in an Open Space. Chemical Engineering Science 117, 137-145.||en
|dc.relation.hasversion||Li, X., Fan, X., Askounis, A., Wu, K., Sefiane, K., Koutsos, V., 2013. An Experimental Study on Dynamic Pore Wettability. Chemical Engineering Science 104, 988-997.||en
|dc.relation.hasversion||Li, X., Fan, X., 2014. Pore Wetting Phenomena: Implications to Enhanced Oil Recovery and Geologic Carbon Storage. International Conference on Applied Energy, ICAE 2014, Taiwan, published in Energy Procedia 61, 2712-2715.||en
|dc.relation.hasversion||Li, X., Fan, X., 2014. Pore Wetting and Its Effect on Breakthrough Pressure in Water-Wet and Oil-Wet Pores. International Conference on Biological and Chemical Science – ICBCS, 2014, Shanghai, China, published in International Journal of Chemical Engineering and Applications 5, 359-362.||en
|dc.relation.hasversion||Li, X., Fan, X., 2013. Experimental Studies on Multiphase Flow in Porous Media and Pore Wettability. International Conference on Chemical and Environmental Engineering 2013, Barcelona, Spain, published in World Academy of Science, Engineering and Technology 74, 739-743.||en
|dc.subject||enhanced oil recovery||en
|dc.title||Experimental studies on pore wetting and displacement of fluid by CO2 in porous media||en
|dc.type||Thesis or Dissertation||en
|dc.type.qualificationname||PhD Doctor of Philosophy||en