Permeability inversion from low‐frequency seismoelectric logs in fluid‐saturated porous formations

Abstract

A B S T R A C TIn this paper, a method is proposed to invert permeability from seismoelectric logs in fluid-saturated porous formations. From the analysis of both the amplitude and the phase of simulated seismoelectric logs, we find that the Stoneley wave amplitude of the ratio of the converted electric field to the pressure (REP) is sensitive to porosity rather than permeability while the tangent of the REP's phase is sensitive to permeability. The REP's phase reflects the phase discrepancy between the electric field and the pressure at the same location in the borehole. We theoretically derive the frequency-dependent expression of the REP of the low-frequency Stoneley wave and find that the tangent of the REP's argument is approximately in inverse proportion to permeability. We obtain an inversion formula and present the permeability inversion method by using the tangent of the REP's phase. To test this method, the permeabilities of different sandstones are inverted from the synthetic full-waveform data of seismoelectric logs. A modified inversion process is proposed based on the analysis of inversion errors, by which the relative errors are controlled below 25% and they are smaller than those of the permeability inversion from the Stoneley wave of acoustic logs.

Thermo Electric Sensitivity Fractal Dimension for Characterizing Shajara Reservoirs of the Permo-Carboniferous Shajara Formation, Saudi Arabia

“…The magnitude of seismo electric current depends on porosity, pore size, zeta potential of the pore surfaces, and elastic properties of the matrix was investigated by [4]. The tangent of the ratio of converted electic field to pressure is approximately in inverse proportion to permeability was studied by [5]. Permeability inversion from seismoelectric log at low frequency was studied by [6].…”

Curvelet-based seismoelectric data processing

“…As it does not exist outside the seismic disturbance, the coseismic wavefield only provides local information restricted to the vicinity of the dipole receivers: when these are deployed inside a borehole, the study of coseismic effects may provide valuable information about the medium’s porosity and permeability near the borehole at depth (Dupuis & Butler 2006; Hu et al. 2007; Guan et al. 2012).…”

A review on electrokinetically induced seismo-electrics, electro-seismics, and seismo-magnetics for Earth sciences

“…The measured amplitude of the normalized coefficient on sandstones is in the range of 1.6 × 10 showed that the normalized coefficient could detect a 0.5 mthick bed of permeability 10 −13 m 2 within a formation of permeability 10 −15 m 2 . On the other hand, Guan et al (2013) modelled the coseismic conversion of Stoneley waves within a borehole and showed that the ratio of the converted electric field to the pressure is sensitive to the porosity rather than to the permeability. This ratio is increased by a factor of 2 for increasing porosity from 10 to 30 %.…”

“…This ratio is increased by a factor of 2 for increasing porosity from 10 to 30 %. The Stoneley wave being sensitive to the permeability, Guan et al (2013) further investigated the phase of the ratio of the converted electric field to the pressure, and showed that the tangent of this phase is sensitive to the permeability. They showed that the phase of the electric field always lags behind that of pressure in the frequency range up to 5 kHz and there is a frequency about 1 kHz for which the tangent of thus phase is minimum.…”

“…Although they did not implement it, they discussed how to extend the finite differences algorithm to deal with stratified media. Recently, Guan et al (2013) proposed a permeability inversion method through the existing relation between SE logs and formation permeability. By working with the Stoneley wave ratio of the converted electric field to pressure (REP), they noticed that its amplitude is sensitive to porosity, while the tangent of its phase is sensitive to permeability.…”