Phase behaviour and related properties of mixtures of solvents and heavy oil

Bitumen is a versatile material widely used by humans, going back many milennia. ¹ It was early used in hunter-gatherer societies as an adhesive when making tools from sticks and stones. In early civilizations it was commonly used as mortar. The black highly viscous material is barely flowing at room temperature and bitumen deposits are usually solid in winter but become softer and workable at higher summer temperatures. Bitumen occurs naturally around lakes and rivers where underground water has brought it to the surface. In many native tribes worldwide bitumen has played an important role as a sealant, waterproofing their (marine) vessels. Today bitumen is mainly used in road constructions (the major component in what we know as asphalt), although the lighter components are distilled off and used in gasoline fuels.

Bitumen has traditionally been produced by surface mining. The thermal process of steam assisted gravity drainage (SAGD) is now widely used to produce bitumen from deeper reservoirs.² The SAGD process is energy consuming and also requires access to substantial amounts of water; it is therefore of considerable interest to develop alternative processes. The semisolid bitumen can be transported in pipelines only if heated or diluted. Diluting the bitumen may change the solubility characteristics. Some solvents may at certain conditions (composition, pressure and temperature) act as antisolvents. This may create additional phase boundaries, solid/liquid or liquid/liquid phases.³ At higher temperatures gas-liquid phases are also to be expected. 

We aim to determine the phase behaviour of bitumen when diluted. Main interests are the phase volumes, distribution coefficients, density and viscosity of mixtures of bitumen and chosen solvents. Understanding the phase boundaries is important both to develop better recovery processes and ease transportation of the bitumen, in turn leading to more efficient and environmentally friendly ways of producing bitumen.

Publications:
1 Krishnan, J. M.; Rajagopal, K. R. Review of the uses and modeling of bitumen from ancient to modern times. Applied Mechanics Reviews 2003, 56, 149-214.
2 Al-Bahlani, A.-M.; Babadagli, T. SAGD laboratory experimental and numerical simulation studies: A review of current status and future issues. J. Pet. Sci. Eng. 2009, 68, 135-150.
3 An example of solid/liquid phases coexisting is the coffee grounds in your morning coffee. Oil in water is an example of liquid/liquid phases coexisting