Estimation of concentration-dependent diffusion coefficient in pressure-decay experiment of heavy oils and bitumen

Ghaderi, Seyyed M.; Tabatabaie, S. Hamed; Hassanzadeh, Hassan; Pooladi‐Darvish, Mehran

doi:10.1016/j.fluid.2011.03.010

Cited by 52 publications

(46 citation statements)

References 24 publications

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“…As solvent moves into oil, pressure drops in the system and the rate of pressure drop is indicative of the solvent content within the oil. Various assumptions and boundary conditions are used to determine constant diffusion coefficients (Zhang et al, 1998;Tharanivasan et al, 2004;Sheikha et al, 2005;Etniman et al, 2010) and concentration-dependent diffusion coefficients (Upreti and Mehrotra, 2000;Ghaderi et al, 2011). In these measurements, the initial solvent volume is fixed, so volume of remaining solvent drops as solvent moves into the oil.…”

Section: Measuring Solvent Mass Transfer Rates Into Heavy Oil and Bitmentioning

confidence: 99%

Evaluation of Diffusion of Light Hydrocarbon Solvents in Bitumen

et al. 2015

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Solvent-based processes are often used as potential recovery agents in bitumen systems, with and without the addition of heat to the solvent. Solvents can sometimes be applied as a liquid phase, during SAGD start-up operations or processes aimed at developing injectivity into the oil. Light hydrocarbon liquids are traditionally tested for this application. Solvent injection may also occur in a vapour state and its objective is to reduce oil viscosity and improve mobility of bitumen under low temperatures Ͻ100°C. In general, hydrocarbon solvents such as propane are often used for this application. The objective of this study is to conduct CT-based measurement of static mixing of bitumen and both liquid and vapour phase solvents, and to quantify some of the time-dependent changes that occur during solvent mixing with bitumen.Diffusion experiments have been conducted with propane and DME (vapour phase) and with propane, DME, pentane and toluene (liquid phase) solvent systems. Solvents are mixed with medium viscosity Peace River bitumen and high viscosity Grosmont bitumen. The Tests are run under constant pressure and temperature, and Computer-Assisted Tomography (CT) is used to monitor mass transfer of solvent into oil as a function of time. The outcome of this study is measurements of mass transfer rates of solvent into oil, and the degree of oil phase swelling during the tests.During solvent injection processes in the field, the rate of mixing is a key parameter that will help in deciding which solvent is optimal for different processes. This study focuses on the rate of solvent mixing with oil. In vapour phase solvent systems, the analysis of the CT images allows for an understanding of the impact of oil phase swelling on the effective rate of penetration of solvent into oil. Overall, the test data provided in this work demonstrates that DME mixes into oil faster than other solvents, and leads to more swelling in a vapour solvent-bitumen system. The analysis of CT data provides an understanding of concentration-dependent diffusion coefficients and limitations from predicting mass transfer using constant coefficients in liquid and vapour solvent systems.

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Section: Measuring Solvent Mass Transfer Rates Into Heavy Oil and Bitmentioning

confidence: 99%

Evaluation of Diffusion of Light Hydrocarbon Solvents in Bitumen

et al. 2015

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“…(i) Many authors (Etminan et al 2013;Sheikha et al 2005;Ghaderi et al 2011) used Henry's law to obtain gas concentration above the interface, assuming that VLE overcomes immediately. This is effective when the quantity of solute dissolved is small and the solution is dilute.…”

Section: Pressure-decay Modelsmentioning

confidence: 99%

“…Nonetheless, it has already been shown in gas-heavy oil experiments that the gas diffusivity coefficient is a function of gas concentration in the oil (Ghaderi et al, 2011). Nonetheless, it has already been shown in gas-heavy oil experiments that the gas diffusivity coefficient is a function of gas concentration in the oil (Ghaderi et al, 2011).…”

Section: Pressure-decay Modelsmentioning

confidence: 99%

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Diffusion Coefficient of CO2 in Light Oil Under Reservoir Conditions Using X-Ray Computed Tomography

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Araujo

Santos³

et al. 2013

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Molecular diffusion is the process describing the natural mixture of miscible fluids, whose main modeling parameter is the molecular diffusion coefficient. This work aims to evaluate the molecular diffusion coefficient for CO 2 -light oil systems under different experimental conditions of pressure. Experimental measurements are based on both pressure decay and computed tomography (CT) scan methods. The oil studied is light oil from Brazilian subsalt oil reservoirs. Tests were carried on a specially constructed vertical high pressure cell, from 2.76 MPa up to 28.96 MPa and at 293.15 K. The swelling effect was also evaluated during the diffusion process considering the height variation of the oil column inside the cell.Molecular diffusion is particularly important for miscible gas flooding processes, as diffusion is a key mechanism controlling the miscibility between oil and gas. The diffusion coefficient determines the rate of mass transfer during the diffusive process that will result in a miscible system. The diffusivity of solvents into light oil in porous media has become of great significance in petroleum engineering, since CO 2 injection has been proposed more and more as the enhanced oil recovery method to be applied in the reserves of conventional oils.Currently, the topic of CO 2 diffusion in light oils is scarcely described in the public literature, while diffusion in CO 2 -heavy oils systems has attracted some attention. Although both diffusion process and swelling effect have a common ground, many differences must be taken into consideration to truly model the mass transfer phenomenon.Diffusion coefficients were obtained using the CT method and the pressure decay technique throughout Etminan et al. (2013) interface resistance model. Both methods have significative discrepancies in coefficients values. The diffusivities obtained from pressure decay were more consistent with published data. Therefore pressure drop technique seems more robust even for CO 2 -light oil mixture, while CT technique needs further improvements. Furthermore, as Etminan et al. (2013) model is applicable only for VLE conditions, an improved model will be required for additional LLE situations.

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“…They studied dissolution of gases such as CH 4 and CO 2 into light or heavy oil (including bitumen) [43][44][45][46]. Unlike CO 2 in water system, density of liquid phase is decreasing with gas dissolution in heavy oil-gas systems.…”

Section: Introductionmentioning

confidence: 99%