Monitoring of Diffusion of Heavy Oils with Hydrocarbon Solvents in the Presence of Sand

Abstract

TX 75083-3836, U.S.A., fax 01-972-952-9435. AbstractMass transfer of solvents in bulk heavy oil and bitumen was monitored successfully using X-ray Computer Assisted Tomography (CAT). Concentration gradients were obtained from analysis of bulk density maps as a function of location and time. Analysis of the data using Fick's Law provided apparent diffusion coefficients, which were consistent with previously published data using different solvents and different oils.A second series of experiments was then performed whereby the heavy oil was mixed with sand at a level that is similar to what expected in heavy oil reservoirs. There was no connate water in the system. Different solvents were then placed on top of the oil/sand mixtures and the diffusion of the solvent into the sand pack was observed. X-ray CAT was used to monitor density and concentration profiles.Oil concentration profiles in solvent were clearly observed but the solvent concentration in the sand pack proved to be more challenging. The same Fickian approach that was used in bulk oil systems was applied to predict apparent diffusion coefficients for the liquid volume portion of the experiment. Preliminary results showed that the apparent diffusion coefficients are of the same order of magnitude as in the bulk oil systems.

NMR relaxometry and diffusometry in characterizing structural, interfacial and colloidal properties of heavy oils and oil sands

“…solvents [88]. When solvent is added to the oil, the viscosity decreases and the T 2 times become longer; T 2gm and the AI of the mixtures also vary with the amount and type of the solvent.…”

“…When solvent is added to the oil, the viscosity decreases and the T 2 times become longer; T 2gm and the AI of the mixtures also vary with the amount and type of the solvent. It was shown that small amounts of solvent produce significant effects, and that the solvents have a larger effect on the most viscous oils [88]. The NMR viscosity predictions of the oil-solvent mixtures were shown to be more accurate than the widely-used Cragoe's method [92].…”

“…The use of NMR to study solvent-heavy oil interactions was also extended to the study of the effects of different solvent concentrations on heavy oils and bitumens [88][89][90][91]. T 2 relaxation time distributions for different oil-solvent mixtures were measured.…”

“…So far, therefore, NMR has been shown to be ideal for non-invasively and accurately monitoring asphaltene precipitation and measuring the density and viscosity of solvent-heavy oil mixtures in bulk samples [88][89][90]94]. …”

Numerical Simulation Study of SAGD Experiment and Investigating Possibility of Solvent Co-Injection

“…The diffusivity coefficient of 3x10 -4 cm 2 /min is used for all of these three solvents. (Salama and Kantzas, 2005) Results show that addition of solvent has a positive effect both on cumulative oil production and WOR. As it can be seen in Figs.…”