We carry out basic research on the thermophysical properties and phase behaviour of fluids and fluid mixtures, and publish our work in internationally-leading scientific journals. Our research is sponsored by UK government agencies, such as the EPSRC, the European Union and industry worldwide. Current and recent research topics include the measurement, modelling and understanding of:
- the phase behaviour of mixtures of CO2 with hydrocarbons and brines under reservoir conditions
- interfacial tension between CO2- and brine-rich phases under reservoir conditions
- diffusion coefficients of CO2 in water, brine and hydrocarbon liquids at high pressures
- the viscosity and density of mixtures at high pressures
- the speed of sound in compressed liquids and mixtures
- thermophysical properties of liquid and gaseous fuels under extreme conditions
These properties are key inputs required in the design and operation of many industrial processes including carbon capture and storage, enhanced oil recovery, hydrocarbon processing, liquid fuel formulation and heat transfer operations.
Much of the experimental research is carried out using bespoke apparatus designed, and often built, in house.
The laboratory is a leading participant in both the Qatar Carbonates and Carbon Storage Research Centre (QCCSRC) and the Clean Fossil and Bioenergy Research Group (CleanFab), and we have fruitful collaborations with colleagues in the Molecular Systems Engineering Group (MSE). The main current areas of activity are described below.
Interfacial properties and reactivity
The primary purpose of this research is to better understand the role of both capillary forces and chemical reactivity in the process of carbon sequestration in deep saline aquifers, especially those containing carbonate minerals. The group is equipped with two view cells for the measurement of interfacial tension (IFT) between partially miscible fluids at pressures up to 50 MPa and temperatures up to 473 K. This equipment has been used to measure the IFT between CO2 and water and brines over wide ranges of pressure, temperature and molality that encompass typical CO2-storage conditions. Current efforts are directed towards understanding the effects on the IFT of impurities that might be present in the CO2 stream and on measuring the angles between CO2, brine and carbonate mineral surfaces.
To study the chemical interactions that occur between CO2-acidified reservoir fluids and carbonate minerals at reservoir conditions, we employ a batch reactor system. This equipment has been used to measure the kinetics of carbonate-mineral dissolution in both water and brines saturated with CO2 at reservoir conditions. The effects of surface-bound impurities on the reactivity of calcite has also been studied.
Phase behaviour is of fundamental importance in many areas of science and technology and the group is therefore very active in the measurement and modelling of phase-equilibrium phenomena. We are equipped with a range of facilities, including both analytical and synthetic apparatus, that allow measurements to be made over very wide ranges of pressure (from 0.005 MPa to 50 MPa) and temperature (from 183 K to 474 K) and for a diversity of chemical systems including hydrocarbons and aqueous systems. Current research is directed mainly to mixtures of CO2 with: hydrocarbons; inorganic gases; brines; and aqueous amine solutions. The results are being modelled using both engineering equations of state and molecular-thermodynamic models such as SAFT.
Single-Phase Thermophysical Properties
In this field, the motivation of our work is to understand the thermodynamic and transport properties of homogeneous fluid mixtures. Two key areas of application are: (a) the behaviour of hydrocarbon reservoir fluids, aquifer fluids and CO2 at various temperature and pressure conditions that represent hydrocarbon fields and CO2 storage conditions; and (b) the performance of various solvents in CO2 capture processes, especially in relation to mass transfer and hydrodynamic calculations. Experiments are designed and performed with state-of-the-art apparatus to determine thermophysical properties of pure and mixed fluids. The measured thermodynamic properties include density, sound speed, and isobaric heat capacity in liquids and gases over wide ranges of temperature and pressure, leading to full thermodynamic characterisation of the fluids under investigation. In the area of transport properties, we measure viscosity and diffusion coefficients at high pressures. Viscosity measurements are made mainly with vibrating-wire instruments developed in our laboratory for application at pressures up to 400 MPa. We have also developed a dual-capillary viscometer for measurements at temperatures up to 600 K, and a Taylor-Dispersion apparatus for measuring diffusion coefficients of dilute solutes.