Technical Paper: Sensitivity Analysis of 3D Surface-Borehole CSEM for a Saudi Arabian Carbonate Reservoir

Society: SEG
Paper Number: 2012-628
Presentation Date: 2012


A realistic surface-to-borehole controlled-source electromagnetic (CSEM) survey was modelled to determine the sensitivity of electromagnetic fields to waterflooding in a typical Saudi Arabian carbonate oil reservoir.  The reservoir saturation changes were modelled over a period of 75 years and then converted to resistivity using Archie's empirical relation.  The overburden model is obtained by upscaling tri-axial resistivity logs from a test well to derive a full anisotropic profile from surface to the reservoir level.  3D Finite Difference (FD) frequency-domain modelling was performed assuming surface galvanic sources with radial and tangential polarization directions relative to the well and with receivers positioned in the reservoir.  Forward modelling and inversion results indicate that electric field measurements in the borehole and the vertical component of it (E3), in particular, may offer the necessary resolution and sensitivity to characterize reservoir saturation variations.

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