Measurements of molecular diffusion coefficients of carbon dioxide, methane and propane in heavy oil under reservoir conditions.

摘要

Design and modeling of solvent-based heavy oil recovery processes require the knowledge of solvent diffusivity in heavy oil. In this thesis study, a non-intrusive pressure decay method is applied to measure the molecular diffusion coefficients of three different gaseous solvents, carbon dioxide, methane and propane, in heavy oil under reservoir pressure and temperature conditions. In the experiment, direct physical contact of the solvent and the heavy oil is made and thereby the pressure in the solvent phase versus time data are accurately measured inside a closed high-pressure diffusion cell at constant temperature, as the solvent gradually dissolves in heavy oil. On the other hand, in terms of the conservation of mass and the equation of state for a real gas, the pressure in the solvent phase is calculated from the analytical solution to the diffusion equation for such a diffusion process. Then, the solvent diffusivity in heavy oil is determined by finding the best match of the numerically calculated pressures with the experimentally measured data. (Abstract shortened by UMI.)