Viscosity and Density of Reservoir Fluids under CO2 Addition

Claudio Calabrese

Supervisors: Prof J. P. Martin Trusler and Prof Geoffrey Maitland

Funding: Qatar Petroleum, Shell, Qatar Science and Technology Park


Carbon capture and storage (CCS) is an emerging industrial technique which represents the best short to medium term option for significantly reducing CO2 emissions in the atmosphere. Geological carbon storage involves complex fluid mixtures comprising hydrocarbons, concentrated brines and CO2 at high temperatures and pressures. Understanding and measuring the thermophysical properties of the above mentioned systems is essential for developing models able to predict the storage performance. In particular, viscosity and density are properties of interest for characterizing reservoir fluid mixtures in the subsurface, developing predictive tools and monitoring post-injection. However significant gaps currently exist in the available experimental data in terms of thermodynamic conditions of the investigated reservoir fluids. As a consequence, more research is needed in this area.

The aim of the PhD project is to provide high quality viscosity and density measurements for concentrated brines and hydrocarbons with dissolved CO2 using a vibrating-wire viscometer/vibrating-tube densimeter apparatus. Figure 1 shows the vibrating-wire viscometer.

In particular, the following systems will be investigated:

  1. Synthetic crude oil - CO2
  2. MgCl2 (aq) - CO2
  3. Na2SO4 (aq) - CO2

A large temperature and pressure range will be studied in order to cover conditions across reservoirs of different depths. The experimental data will be used as a benchmark in the research field. The results for both properties will be correlated as functions of temperature, pressure, salt molality and the mole fraction of dissolved CO2. These studies will benefit both the industrial field and the academic research, where accurate viscosity measurements are required.

The main achievements so far has been the development and validation of a semi-empirical working equation for studying the viscosity of high-conductive fluids – such as concentrated brine – when using a vibrating-wire viscometer. 

claudio pic