Modeling the interface resistance in low soluble gaseous solvents-heavy oil systems

► Dilute dissolution of gases into heavy oil was modeled accounting for 3 parameters. ► The unknown parameters were diffusion and mass transfer coefficients and solubility. ► It models both equilibrium and non-equilibrium interface boundary conditions. ► This model uses the pressure decay data direc...

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Bibliographic Details
Published in:Fuel (Guildford) 2013-03, Vol.105, p.672-687
Main Authors: Reza Etminan, S., Pooladi-Darvish, Mehran, Maini, Brij B., Chen, Zhangxin
Format: Article
Language:English
Subjects:
Applied sciences
Characteristics of producing layers. Reservoir geology. In situ fluids
Crude oil, natural gas and petroleum products
Crude oil, natural gas, oil shales producing equipements and methods
Diffusion measurement
Energy
Energy. Thermal use of fuels
Exact sciences and technology
Fuels
Heavy oilBitumen
Interface resistance
Pressure decay technique
Prospecting and production of crude oil, natural gas, oil shales and tar sands
Solubility
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Summary:► Dilute dissolution of gases into heavy oil was modeled accounting for 3 parameters. ► The unknown parameters were diffusion and mass transfer coefficients and solubility. ► It models both equilibrium and non-equilibrium interface boundary conditions. ► This model uses the pressure decay data directly for the parameter estimation. ► Determination of k value does not necessarily imply for physical interface resistance. ► Correct modeling of interface physics leads to accurate estimation of the parameters. Measurement of gas diffusivity in reservoir fluids is of great interest for a number of applications, and among different methods for the measurement, the Pressure Decay method has received special attention due to its simplicity. In this technique, a non-volatile quiescent oil column is brought in contact with a diffusing single component gas from the top and the rate of change of gas pressure in the gas cap is recorded. The interpretation of outcomes is based on solution of a forward problem, which sometimes invokes a complicated boundary condition. In this work, an analytical solution is presented for the most general form of the boundary condition which models the interface. It takes into account all mass transfer key parameters including gas solubility, a diffusion coefficient and a possible interfacial resistance. The effect of resistance against mass diffusion at the interface is usually neglected in modeling. Through this solution, the role of interface resistance is better explained and one can realize how the resistance exactly affects the diffusion process. A detailed sensitivity analysis of each parameter is conducted and specifically in the case of interface resistance, it is illustrated that a numerical value can be reported for the interfacial resistance while it does not affect or hinder the diffusion process physically. This could unnecessarily increase the degree of freedom of the backward problem, and may lead to misleading parameter estimation results (despite a good match of the measurements). Using our new interface boundary condition reveals that some of the previous works on the modeling of interface resistance are subject to underestimation of the rate of gas dissolution which may lead to erroneous estimation of parameters.
ISSN:0016-2361
1873-7153
DOI:10.1016/j.fuel.2012.08.048