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, 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 or H2 and brine phases under reservoir conditions
- diffusion coefficients of CO2 or H2 in water, brine or hydrocarbon liquids at high pressures
- solubility of CO2 or H2 in aqueous media, including carbon capture solvents and reservoir brines
- the viscosity and density of mixtures at high pressures
- the speed of sound in compressed gasses and liquids
- 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, transportation and storage, hydrogen production, transportation and storage, hydrocarbon processing, sustainable liquid fuel formulation, refrigeration and heat transfer operations.
Much of the experimental research is carried out using bespoke apparatus designed, and often built, in house. The main current areas of activity are described below.
Main Research
The primary purpose of this research is to better understand the role of both capillary forces and chemical reactivity in process such as geological carbon storage, underground hydrogen storage or natural hydrogen production. 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 or H2 and water and brines over wide ranges of pressure, temperature and molality that encompass typical storage conditions. Current efforts are directed towards better understanding the IFTs between gas-, brine- and hydrocarbon-rich fluid phases at subsurface conditions.
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. We have also recently completed a study of olivine dissolution in CO2-acidified waters and of the subsequent precipitation of insoluble carbonates in the process of carbon mineralisation.
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 473 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 carbon-capture solvents. We are also investigating the solubility of H2 in various brines at high pressures. The results are being modelled using both engineering equations of state and molecular-thermodynamic models such as SAFT.
In this field, the motivation of our work is to understand the thermodynamic and transport properties of homogeneous fluid mixtures. Three key areas of study are: (a) the properties of pure compressed liquid and supercritical hydrogen, especially by means of very-precise measurements of the speed of sound; (b) the behaviour of mixtures of reservoir fluids and either CO2 or H2 at various temperature and pressure conditions representative of subsurface storage conditions; and (c) 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 Taylor-Dispersion apparatus for measuring diffusion coefficients of dilute solutes.