QUANTITATIVE EVALUATION OF FORMATION PERMEABILITY FROM ACOUSTIC AND ELECTRIC STONELEY WAVES

2010 ◽  
Vol 02 (03) ◽  
pp. 585-615 ◽  
Author(s):  
BORIS D. PLYSHCHENKOV ◽  
ANATOLY A. NIKITIN
Keyword(s):  
Electric Field ◽  
Quantitative Evaluation ◽  
Pressure Field ◽  
Plane Waves ◽  
Stoneley Wave ◽  
Axial Component ◽  
Electrokinetic Phenomena ◽  
Stoneley Waves ◽  
Complex Valued ◽  
Analytical Expressions

Numerical experiments based on Pride's model of electrokinetic phenomena have shown that electromagnetic Stoneley waves as well as pressure Stoneley waves are most sensitive to permeability variations. A new way for quantitative evaluation of any value of formation permeability is presented. It is based on simultaneous measurement of pressure field and axial component of electric field excited by an acoustic source in fluid-filled borehole with help from a set of receivers in borehole. Frequency dependence of ratio of the complex-valued amplitudes of the electric Stoneley wave to the pressure Stoneley wave obtained as a result of plane waves decomposition of pressure field and mentioned component of electric field carries important information about permeability. The ratio of the real part of this ratio to its imaginary part is very sensitive to permeability variations. The approximate analytical expressions for this ratio derived for open and sealed pores on borehole wall are base for construction of a new way of quantitative evaluation of formation permeability.

BOREHOLE ACOUSTIC AND ELECTRIC STONELEY WAVES AND PERMEABILITY

2010 ◽  
Vol 18 (02) ◽  
pp. 87-115 ◽  
Author(s):  
BORIS D. PLYSHCHENKOV ◽  
ANATOLY A. NIKITIN
Keyword(s):  
Electric Field ◽  
Pressure Field ◽  
Stoneley Wave ◽  
Axial Component ◽  
Acoustic Source ◽  
Electrokinetic Phenomena ◽  
Plane Wave Decomposition ◽  
Wave Decomposition ◽  
Complex Valued ◽  
Analytical Expressions

New way for quantitative evaluation of any value of formation permeability based on numerical experiments with Pride's model of electrokinetic phenomena is presented. This approach is based on simultaneous measurement of pressure field and axial component of electric field excited by an acoustic source in fluid-filled borehole with help a set of receivers in borehole. Frequency dependence of ratio of the complex-valued amplitudes of the electric Stoneley wave to the pressure Stoneley wave obtained as a result of plane-wave decomposition of pressure field and mentioned component of electric field carries important information about permeability. In case of open and sealed pores on borehole wall were obtained enough simple analytical expressions for this ratio.

scholarly journals Remote sensing of a NTC radio source from a Cluster tilted spacecraft pair

2013 ◽  
Vol 31 (11) ◽  
pp. 2097-2121 ◽  
Author(s):  
P. M. E. Décréau ◽  
S. Kougblénou ◽  
G. Lointier ◽  
J.-L. Rauch ◽  
J.-G. Trotignon ◽  
...  
Keyword(s):  
Electric Field ◽  
Circular Polarization ◽  
Source Region ◽  
Plane Waves ◽  
Geomagnetic Latitude ◽  
Magnetic Activity ◽  
Spectral Signature ◽  
Time Interval ◽  
Field Polarization ◽  
Electric Field Polarization

Abstract. The Cluster mission operated a "tilt campaign" during the month of May 2008. Two of the four identical Cluster spacecraft were placed at a close distance (~50 km) from each other and the spin axis of one of the spacecraft pair was tilted by an angle of ~46°. This gave the opportunity, for the first time in space, to measure global characteristics of AC electric field, at the sensitivity available with long boom (88 m) antennas, simultaneously from the specific configuration of the tilted pair of satellites and from the available base of three satellites placed at a large characteristic separation (~1 RE). This paper describes how global characteristics of radio waves, in this case the configuration of the electric field polarization ellipse in 3-D-space, are identified from in situ measurements of spin modulation features by the tilted pair, validating a novel experimental concept. In the event selected for analysis, non-thermal continuum (NTC) waves in the 15–25 kHz frequency range are observed from the Cluster constellation placed above the polar cap. The observed intensity variations with spin angle are those of plane waves, with an electric field polarization close to circular, at an ellipticity ratio e = 0.87. We derive the source position in 3-D by two different methods. The first one uses ray path orientation (measured by the tilted pair) combined with spectral signature of magnetic field magnitude at source. The second one is obtained via triangulation from the three spacecraft baseline, using estimation of directivity angles under assumption of circular polarization. The two results are not compatible, placing sources widely apart. We present a general study of the level of systematic errors due to the assumption of circular polarization, linked to the second approach, and show how this approach can lead to poor triangulation and wrong source positioning. The estimation derived from the first method places the NTC source region in the dawn sector, at a large L value (L ~ 10) and a medium geomagnetic latitude (35° S). We discuss these untypical results within the frame of the geophysical conditions prevailing that day, i.e. a particularly quiet long time interval, followed by a short increase of magnetic activity.

Focusing of Proteins in a Horseshoe Microchannel

2008 ◽  
Author(s):  
Jaesool Shim ◽  
Prashanta Dutta ◽  
Cornelius F. Ivory
Keyword(s):  
Capillary Electrophoresis ◽  
Electric Field ◽  
Isoelectric Focusing ◽  
Ph Gradient ◽  
Complex Geometries ◽  
Electrokinetic Phenomena ◽  
Double Peaks ◽  
Zone Electrophoresis ◽  
Carrier Ampholytes ◽  
Ph Range

Ampholyte based isoelectric focusing (IEF) simulation was conducted to study dispersion of proteins in a horseshoe microchannel. Four model proteins (pls = 6.49, 7.1, 7.93 and 8.6) are focused in a 1 cm long horseshoe channel under an electric field of 300 V/cm. The pH gradient is formed in the presence of 25 biprotic carrier ampholytes (ΔpK = 3.0) within a pH range of 6 to 9. The proteins are focused at 380 sec in a nominal electric field of 300 V/cm. Our numerical results show that the band dispersions of a protein are large during the marching stage, but the dispersions are significantly reduced when the double peaks start to merge. This rearrangement of spreading band is very unique compared to linear electrokinetic phenomena (capillary electrophoresis, zone electrophoresis or electroosmosis) and is independent of channel position and channel shape. Hence, one can perform IEF in complex geometries without incorporating hyperturns.

The Nuclear Quadrupole Interaction of 204mPb in Cadmium Monitored by γ–γ –Perturbed Angular Correlations

2002 ◽  
Vol 57 (6-7) ◽  
pp. 586-590 ◽  
Author(s):  
W. Tröger ◽  
M. Dietrich ◽  
J. P. Araujo ◽  
J. G. Correia ◽  
H. Haas
Keyword(s):  
Electric Field ◽  
Electric Field Gradient ◽  
Field Gradient ◽  
Plane Waves ◽  
Nuclear Quadrupole Interaction ◽  
Full Potential ◽  
Angular Correlations ◽  
Time Differential ◽  
On Line ◽  
First Time

For the first time the nuclear probe 204mPb was produced at the on-line isotope separator ISOLDE at CERN and used for time differential perturbed angular correlation experiments. The electric field gradient of 204mPb at room temperature in Cd metal was determined to be = 19(1) 1021 V/m2. Ab initio-calculations of the electric field gradient for the impurities Pt to Bi in cadmium were performed with the full-potential linearized augmented plane waves code WIEN97 to interpret this result. For Au, Hg and Pb, where experimental results are now available, these agree with the calculations within 10 %.

Stoneley wave velocity variation

2020 ◽  
pp. 2050030
Author(s):  
Sergey V. Kuznetsov
Keyword(s):  
Numerical Analysis ◽  
Wave Velocity ◽  
Rayleigh Waves ◽  
Secular Equation ◽  
Shear Waves ◽  
Velocity Variation ◽  
Stoneley Wave ◽  
Velocity Dependence ◽  
Stoneley Waves ◽  
Negative Poisson's Ratio

Stoneley wave velocity variation is analyzed by solving the modified Scholte secular equation for velocity of Stoneley waves, allowing to find dependency of the Stoneley wave velocity on the Wiechert parameter and construct a set of inequalities that confines region of existence for the appropriate root of the secular equation. Numerical analysis for Stoneley wave velocity dependence on the Wiechert parameter for both auxetics (materials with negative Poisson’s ratio) and nonauxetics revealed the presence of (i) asymptotes indicating degeneracy of Stoneley waves into the corresponding Rayleigh waves; and (ii) common extremums relating to degeneracy of Stoneley waves into the corresponding bulk shear waves.

Shear velocity logging in slow formations using the Stoneley wave

Geophysics ◽  
1986 ◽  
Vol 51 (1) ◽  
pp. 137-147 ◽  
Author(s):  
Jeffry L. Stevens ◽  
Steven M. Day
Keyword(s):  
Error Estimates ◽  
Shear Velocity ◽  
Low Noise ◽  
Head Wave ◽  
Inversion Method ◽  
Stoneley Wave ◽  
Fluid Viscosity ◽  
High Quality ◽  
Stoneley Waves ◽  
Compressional Velocity

We apply an iterative, linearized inversion method to Stoneley waves recorded on acoustic logs in a borehole. Our objective is to assess inversion of Stoneley wave phase and group velocity as a practical technique for shear velocity logging in slow formations. Indirect techniques for shear logging are of particular importance in this case because there is no shear head wave arrival. Acoustic logs from a long‐spaced sonic tool provided high‐quality, low‐noise data in the 1 to 10 kHz band for this experiment. A shear velocity profile estimated by inversion of a 60 ft (18 ⋅ 3 m) section of full‐wave acoustic data correlates well with the P‐wave log for the section. The inferred shear velocity ranges from 60 to 90 percent of the sound velocity of the fluid. Formal error estimates on the shear velocity are everywhere less than 5 percent. Moreover, application of the same inversion method to synthetic waveforms corroborates these error estimates. Finally, a synthetic acoustic waveform computed from inversion results is an excellent match to the observed waveform. On the basis of these results, we conclude that Stoneley‐wave inversion constitutes a practical, indirect, shear‐logging technique for slow formations. Success of the shear‐logging method depends upon availability of high‐quality, low‐noise waveform data in the 1 to 4 kHz band. Given good prior estimates of compressional velocity and density of the borehole fluid, only rough estimates of borehole radius and formation density and compressional velocity are required. The existing inversion procedure also yields estimates of formation Q inferred from spectral amplitudes of Stoneley waves. This extension of the method is promising, since amplitudes of Stoneley waves in a slow formation are highly sensitive to formation Q. Attenuation caused by formation Q dominates over attenuation caused by fluid viscosity if the viscosity is less than about [Formula: see text]. However, Stoneley‐wave amplitudes are also sensitive to gradients in shear velocity in the direction of propagation. In some cases, correction for the effects of shear‐velocity gradients is required to obtain the formation Q from Stoneley‐wave attenuation.

Simulation of borehole sonic waveforms in dipping, anisotropic, and invaded formations

Geophysics ◽  
2011 ◽  
Vol 76 (4) ◽  
pp. E127-E139 ◽  
Author(s):  
Robert K. Mallan ◽  
Carlos Torres-Verdín ◽  
Jun Ma
Keyword(s):  
Wave Propagation ◽  
Shear Modulus ◽  
Symmetry Axis ◽  
Transverse Isotropy ◽  
Cutoff Frequency ◽  
Dispersion Curves ◽  
Flexural Wave ◽  
Stoneley Wave ◽  
Stoneley Waves ◽  
The Impact

A numerical simulation study has been made of borehole sonic measurements that examined shoulder-bed, anisotropy, and mud-filtrate invasion effects on frequency-dispersion curves of flexural and Stoneley waves. Numerical simulations were considered for a range of models for fast and slow formations. Computations are performed with a Cartesian 3D finite-difference time-domain code. Simulations show that presence of transverse isotropy (TI) alters the dispersion of flexural and Stoneley waves. In slow formations, the flexural wave becomes less dispersive when the shear modulus (c44) governing wave propagation parallel to the TI symmetry axis is lower than the shear modulus (c66) governing wave propagation normal to the TI symmetry axis; conversely, the flexural wave becomes more dispersive when c44 > c66. Dispersion decreases by as much as 30% at higher frequencies for the considered case where c44 < c66. Dispersion of Stoneley waves, on the other hand, increases in TI formations when c44 > c66 and decreases when c44 < c66. Dispersion increases by more than a factor of 2.5 at higher frequencies for the considered case where c44 < c66. Simulations also indicate that the impact of invasion on flexural and Stoneley dispersions can be altered by the presence of TI. For the case of a slow formation and TI, where c44 decreases from the isotropic value, separation between dispersion curves for cases with and without the presence of a fast invasion zone increases by as much as 33% for the flexural wave and by as much as a factor of 1.4 for the Stoneley wave. Lastly, presence of a shoulder bed intersecting the sonic tool at high dip angles can alter flexural dispersion significantly at low frequencies. For the considered case of a shoulder bed dipping at 80°, ambiguity in the flexural cutoff frequency might lead to shear-wave velocity errors of 8%–10%.

scholarly journals ELECTROPHORESIS IN THE TOTAL (CONSTANT AND ALTERNATING) ELECTRIC FIELD. II. PECULIARITIES OF THE COMBINED IMPACT OF ALTERNATING AND CONSTANT ELECTRIC FIELDS

2020 ◽  
Vol 30 (4) ◽  
pp. 46-51
Author(s):  
B. P. Sharfarets ◽  
Keyword(s):  
Electric Field ◽  
Electric Fields ◽  
Constant Electric Field ◽  
Electrokinetic Phenomena ◽  
Alternating Electric Fields ◽  
Alternating Electric Field ◽  
Electroacoustic Transducer ◽  
Dispersed Medium ◽  
Hydrodynamic Field ◽  
Combined Impact

The hydrodynamics of electrophoresis under the simultaneous impact of constant and alternating electric fields is considered. It has been shown that when the constant and alternating external fields are combined, the energy of the constant electric field is transferred into the alternating hydrodynamic field. An example is given of a dispersed medium in which a giant dispersion of the dielectric constant can arise, which in turn can contribute to an increase in the total electrophoresis rate. Analogies of the behavior of the considered dispersed medium with the action of an electroacoustic transducer based on the use of electrokinetic phenomena are given.

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