Diffusivity of CO₂, CH₄, C₂H₆ and N₂ in athabasca bitumen

Abstract

Experimental data for the diffusivity of carbon dioxide, methane, ethane and nitrogen in Athabasca bitumen are presented in the range 25–90°C at 4 and 8 MPa. The diffusivity of these gases has been determined as a function of gas concentration in bitumen using a non‐intrusive experim̀ental method. The diffusivity of gas in general is found to increase with temperature and pressure, and is a unimodal function of concentration. A correlation is provided for the average diffusivity of these gases as a function of temperature.

Determination of gas dispersion in vapor extraction of heavy oil and bitumen

“…To match Vapex oil production rates, researchers (Dunn et al, 1989;Lim et al, 1996;Das and Butler, 1998;Oduntan et al, 2001) had to use different values of dispersion, all of which are quite higher than molecular diffusion. These values indicate a strong concentration dependence of dispersion (Boustani and Maini, 2001) as observed in the case of molecular diffusion (Upreti and Mehrotra, 2002).…”

A Novel Technique to Determine Concentration-Dependent Solvent Dispersion in Vapex

“…Equation (12) and Equation (14) are highly non-linear partial differential equations. Therefore, two undetermined adjoint variables ( , , ) t r z  and ( , ) tr  are introduced into Equation (9) to yield the following unconstrained objective functional: …”

“…A few studies exist on the determination of dispersion of various solvents used in Vapex. Boustani and Maini [10] have shown a strong concentration dependence of dispersion, as observed in the case of molecular diffusion by Upreti and Mehrotra [11,12]. Kapadia et al [7] developed and simulated a mathematical model with a linear concentration-dependent dispersion to determine gas dispersion during the vapor extraction of Cold Lake bitumen from a rectangular block of homogeneous porous medium using butane.…”

Improved Heavy Oil Recovery by VAPEX Process in the Presence of Vertical and Horizontal Fractures

“…Upreti and Mehrotra 10) found that the diffusivity of gases in general increases with pressure. Figure 8 shows the changes in average diffusivity of solvent with pressure.…”

“…11 (Experiment No. 5,6,9,10). In these experiments, the number of fractures surrounding the matrix block was changed by removing some of the strips and filling cavities (fractures).…”