(636b) Estimation of Phase Equilibrium for Water-Heavy Oil System with Structural Information of Heavy Oil Components

Extra heavy oil, such as Canadian oil sand bitumen, Venezuelan Orinoco tar sand, is an important natural resource to deal with the growth in worldwide oil demand. However, transportation from the wellhead to the refinery or shipping facility presents an important problem for the development of extra heavy crude oil reserves. Supercritical water cracking (SCWC) technology is one of heavy oil partial upgrading technologies to produce the pipeline-transportable synthetic crude oil and this technology has been getting attention as a solution for the problem related the transportation of heavy oil. For the process design of SCWC technology, it is important to understand physical properties of heavy oil and phase equilibrium in water-heavy oil system under the high temperature and high pressure condition.

In the last decade, analytical techniques have advanced significantly, for example, high-resolution mass spectrometry, and this had made it possible to obtain molecule-level information about heavy petroleum feedstocks. In particular, the combination of Fourier transform ion cyclotron resonance mass spectrometry (FT-ICR MS) and soft ionization techniques, such as atmospheric pressure photo ionization (APPI), is an excellent tool to obtain structural and compositional information about highly complex mixtures of hydrocarbons. This technique can provide a better understanding of the structure and composition of heavy petroleum fractions, and these structural and compositional information have a potential to improve the accuracy in the estimation of high temperature and pressure phase equilibrium for water-heavy oil system.

In this study, the estimation method of phase equilibrium with Peng-Robinson equation of state (EoS) and the structural information of heavy oil components is proposed. Middle Eastern atmospheric residue (AR) was used as a typical heavy oil sample. To obtain the structural information, Middle Eastern AR was analyzed by FT-ICR MS with a fragmentation method, collision induced dissociation (CID). In this study, we focused on the core structure which is composed of aromatic rings, naphthenic rings and heteroatom-containing functional groups and which is the most important structure because of its effects on physical properties. An estimation method of core structures comprising heavy oil components was developed and it was confirmed that it could assign core structures contained in heavy oil components. In addition, based on the structural information obtained by the combination of CID FT-ICR MS analysis and the core structure estimation, the correlation and prediction of phase equilibrium in water-heavy oil system was performed with Peng-Robinson EoS. The proposed method could provide the better estimation than the previous method without using the structural information.