Seismoelectric response of heavy oil reservoirs: theory and numerical modelling

Authors

  • A. Revil,

    1. Colorado School of Mines, Department of Geophysics, Green Center, 1500 Illinois street, 80401 Golden, CO, USA. E-mail: arevil@mines.edu
    2. LGIT, UMR 5559, CNRS, Equipe Volcan, Université de Savoie, 73376 Le Bourget-du-lac Cedex, France
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  • A. Jardani

    1. Colorado School of Mines, Department of Geophysics, Green Center, 1500 Illinois street, 80401 Golden, CO, USA. E-mail: arevil@mines.edu
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    • *

      Now at: M2C, UMR 6143, CNRS, Morphodynamique Continentale et Côtière, Université de Rouen, 76821 Mont Saint Aignan, France.


SUMMARY

We consider a linear poroelastic material filled with a linear viscoelastic solvent like wet heavy oils (oil as opposed to water or brines is wetting the surfaces of the pores). We extend the electrokinetic theory in the frequency domain accounting for the relaxation effects associated with resonance of the viscoelastic fluid. The fluid is described by a generalized Maxwell rheology with a distribution of relaxation times given by a Cole–Cole distribution. We use the assumption that the charges of the diffuse layer are uniformly distributed in the pore space (Donnan model). The macroscopic constitutive equations of transport for the seepage velocity and the current density have the form of coupled Darcy and Ohm equations with frequency-dependent material properties. These equations are combined with an extended Frenkel–Biot model describing the deformation of the poroelastic material filled with the viscoelastic fluid. In the mechanical constitutive equations, the effective shear modulus is frequency dependent. An amplification of the seismoelectric conversion is expected in the frequency band where resonance of the generalized Maxwell fluid occurs. The seismic and seismoelectric equations are modelled using a finite element code with PML boundary conditions. We found that the DC-value of the streaming potential coupling coefficient is also very high. These results have applications regarding the development of new non-intrusive methods to characterize shallow heavy oil reservoirs in tar sands and DNAPL contaminant plumes in shallow aquifers.

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