Experimental PVT Study of the Phase Behavior of Carbon Dioxide + Heavy Oil Mixtures

Open pit mining can only be used to produce a fraction (15-20 %) of the vast heavy oil and bitumen resources in Canada. Alternative technologies such as gas injection can be used to access the resources trapped in deeper layers of earth. Phase behavior data is instrumental in designing such processes. CO2 + heavy oil mixtures are opaque to visible light and viscous, and present phase behavior, phase composition and thermo-physical property measurement challenges, especially at high CO2 mass fractions. X-ray computer-assisted tomography can be used to study such “ill-behaved” materials.;In this work, the phase behavior of Athabasca bitumen + CO2 and Maya crude oil + CO2 is briefed. A literature review is presented on the previous research works (mostly experimental studies) done on CO2 + heavy oil and similar mixtures. Important aspects of phase behavior such as type of phase behavior, the onset CO2 concentration of LLV behavior, K-point (L1=V, L2) data, two-phase critical point (L=V), CO2 solubility in liquid phase and asphaltene precipitation are investigated. The experimental technique and data analysis methods are elaborated on in detail wherever needed. Different schemes, inspired by Henry’s law and conjugate measurements, to estimate the phase boundaries of mixtures in two-phase region are presented and tested on the literature data. Furthermore, solubility of CO2 in the liquid phase, type of phase behavior and phase diagrams and new critical points data as well as LLV onset concentration data for the subject mixtures are presented in a broad range of temperature, pressure and composition. Some liquid-liquid diffusion data for the two subject mixtures are also presented.