Abstract

The deposition of asphaltene in porous media and their interaction with rock and fluids represent complex phenomena which needs to be investigated under dynamic flowing condition. It could occur by reducing mobility (λ=k/μ) in three probable mechanisms of asphaltene included damage: a) blocking pore throat, b) altering wettability, and c) increasing the reservoir fluid viscosity and can have strong effect on oil production through heavy oil recovery, miscible flooding, and even primary recovery. Many experiments were performed by researchers to determine the amount of deposition and permeability decline but the boundaries in which the asphaltene deposited in oil or at the pore surface was not determined, thus the models introduced have some difficulties using all parameters.

In this paper, a mathematical model is developed constructing to simulate rock-fluid interactions describing permeability decline due to asphaltene deposition. The model considers the second stage (if separated into liquid phase precipitation and pore surface deposition) of asphaltene deposition in which n-hexane used to flocculate asphaltene particles in order to determine the effect of deposition on sandstone rock due to changing of pressure, temperature, and composition of reservoir oil. The influences of various injection rates and concentrations are considered carefully.

This model simulation and corresponding analytical method is applied using laboratory data gained by performing various dynamic displacement experiments with pre-separated oil asphaltene content resulted a close agreement so it could predict the trend of permeability reduction due to deposition of asphaltene. So the procedure of matching the parameters is described here.

This model can be used for analysis of laboratory core tests of formation damage due to flocculated asphaltene particles. Thus, the present study leads to a new insight into the mathematical explanation of flow behavior in porous media.

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