P-wave attenuation measurements from laboratory resonance and sonic waveform data

Geophysics ◽  
1989 ◽  
Vol 54 (1) ◽  
pp. 76-81 ◽  
Author(s):  
D. Goldberg ◽  
B. Zinszner
Keyword(s):  
Wave Attenuation ◽  
Compressional Wave ◽  
P Wave ◽  
Laboratory Measurements ◽  
Frequency Range ◽  
Waveform Data ◽  
Sonic Log ◽  
In Situ Conditions ◽  
The Mean

We computed compressional‐wave velocity [Formula: see text] and attenuation [Formula: see text] from sonic log waveforms recorded in a cored, 30 m thick, dolostone reservoir; using cores from the same reservoir, laboratory measurements of [Formula: see text] and [Formula: see text] were also obtained. We used a resonant bar technique to measure extensional and shear‐wave velocities and attenuations in the laboratory, so that the same frequency range as used in sonic logging (5–25 kHz) was studied. Having the same frequency range avoids frequency‐dependent differences between the laboratory and in‐situ measurements. Compressional‐wave attenuations at 0 MPa confining pressure, calculated on 30 samples, gave average [Formula: see text] values of 17. Experimental and geometrical errors were estimated to be about 5 percent. Measurements at elevated effective pressures up to 30 MPa on selected dolostone samples in a homogeneous interval showed mean [Formula: see text] and [Formula: see text] to be approximately equal and consistently greater than 125. At effective stress of 20 MPa and at room temperature, the mean [Formula: see text] over the dolostone interval was 87, a minimum estimate for the approximate in‐situ conditions. We computed compressional‐wave attenuation from sonic log waveforms in the 12.5–25 kHz frequency band using the slope of the spectral ratio of waveforms recorded 0.914 m and 1.524 m from the source. Average [Formula: see text] over the interval was 13.5, and the mean error between this value and the 95 percent confidence interval of the slope was 15.9 percent. The laboratory measurements of [Formula: see text] under elevated pressure conditions were more than five times greater than the mean in‐situ values. This comparison shows that additional extrinsic losses in the log‐derived measurement of [Formula: see text], such as scattering from fine layers and vugs or mode conversion to shear energy dissipating radially from the borehole, dominate the apparent attenuation.

Sonic to ultrasonic Q of sandstones and limestones: Laboratory measurements at in situ pressures

Geophysics ◽  
2009 ◽  
Vol 74 (2) ◽  
pp. WA93-WA101 ◽  
Author(s):  
Clive McCann ◽  
Jeremy Sothcott
Keyword(s):  
Wave Attenuation ◽  
Shear Waves ◽  
Compressional Wave ◽  
Ultrasonic Frequency ◽  
Laboratory Measurements ◽  
Compressional Waves ◽  
Wave Velocities ◽  
Poisson's Ratios ◽  
Poisson’S Ratios

Laboratory measurements of the attenuation and velocity dispersion of compressional and shear waves at appropriate frequencies, pressures, and temperatures can aid interpretation of seismic and well-log surveys as well as indicate absorption mechanisms in rocks. Construction and calibration of resonant-bar equipment was used to measure velocities and attenuations of standing shear and extensional waves in copper-jacketed right cylinders of rocks ([Formula: see text] in length, [Formula: see text] in diameter) in the sonic frequency range and at differential pressures up to [Formula: see text]. We also measured ultrasonic velocities and attenuations of compressional and shear waves in [Formula: see text]-diameter samples of the rocks at identical pressures. Extensional-mode velocities determined from the resonant bar are systematically too low, yielding unreliable Poisson’s ratios. Poisson’s ratios determined from the ultrasonic data are frequency corrected and used to calculate thesonic-frequency compressional-wave velocities and attenuations from the shear- and extensional-mode data. We calculate the bulk-modulus loss. The accuracies of attenuation data (expressed as [Formula: see text], where [Formula: see text] is the quality factor) are [Formula: see text] for compressional and shear waves at ultrasonic frequency, [Formula: see text] for shear waves, and [Formula: see text] for compressional waves at sonic frequency. Example sonic-frequency data show that the energy absorption in a limestone is small ([Formula: see text] greater than 200 and stress independent) and is primarily due to poroelasticity, whereas that in the two sandstones is variable in magnitude ([Formula: see text] ranges from less than 50 to greater than 300, at reservoir pressures) and arises from a combination of poroelasticity and viscoelasticity. A graph of compressional-wave attenuation versus compressional-wave velocity at reservoir pressures differentiates high-permeability ([Formula: see text], [Formula: see text]) brine-saturated sandstones from low-permeability ([Formula: see text], [Formula: see text]) sandstones and shales.

High-frequency seismic response during permeability reduction due to biopolymer clogging in unconsolidated porous media

Geophysics ◽  
2013 ◽  
Vol 78 (6) ◽  
pp. EN117-EN127 ◽  
Author(s):  
Tae-Hyuk Kwon ◽  
Jonathan B. Ajo-Franklin
Keyword(s):  
Porous Media ◽  
Seismic Response ◽  
Wave Velocity ◽  
Wave Attenuation ◽  
P Wave ◽  
Ultrasonic Frequency ◽  
Permeability Reduction ◽  
Frequency Range ◽  
P Wave Velocity

The accumulation of biopolymers in porous media, produced by stimulating either indigenous bacteria or artificially introduced microbes, readily blocks pore throats and can effectively reduce bulk permeability. Such a microbial clogging treatment can be used for selective plugging of permeable zones in reservoirs and is considered a potentially promising approach to enhance sweep efficiency for microbial enhanced oil recovery (MEOR). Monitoring in situ microbial growth, biopolymer formation, and permeability reduction in the reservoir is critical for successful application of this MEOR approach. We examined the feasibility of using seismic signatures (P-wave velocity and attenuation) for monitoring the in situ accumulation of insoluble biopolymers in unconsolidated sediments. Column experiments, which involved stimulating the sucrose metabolism of Leuconostoc mesenteroides and production of the biopolymer dextran, were performed while monitoring changes in permeability and seismic response using the ultrasonic pulse transmission method. We observed that L. mesenteroides produced a viscous biopolymer in sucrose-rich media. Accumulated dextran, occupying 4%–6% pore volume after [Formula: see text] days of growth, reduced permeability more than one order of magnitude. A negligible change in P-wave velocity was observed, indicating no or minimal change in compressive stiffness of the unconsolidated sediment during biopolymer formation. The amplitude of the P-wave signals decreased [Formula: see text] after [Formula: see text] days of biopolymer production; spectral ratio analysis in the 0.4–0.8-MHz band showed an approximate 30%–50% increase in P-wave attenuation ([Formula: see text]) due to biopolymer production. A flow-induced loss mechanism related to the combined grain/biopolymer structure appeared to be the most plausible mechanism for causing the observed increase in P-wave attenuation in the ultrasonic frequency range. Because permeability reduction is also closely linked to biopolymer volume, P-wave attenuation in the ultrasonic frequency range appears to be an effective indicator for monitoring in situ biopolymer accumulation and permeability reduction and could provide a useful proxy for regions with altered transport properties.

Influence of Light Intensity on Methanotrophic Bacterial Activity in Petit Saut Reservoir, French Guiana

1999 ◽  
Vol 65 (2) ◽  
pp. 534-539 ◽  
Author(s):  
J. F. Dumestre ◽  
J. Guézennec ◽  
C. Galy-Lacaux ◽  
R. Delmas ◽  
S. Richard ◽  
...  
Keyword(s):  
Methane Emission ◽  
French Guiana ◽  
Methanotrophic Bacteria ◽  
Phospholipid Analysis ◽  
In Situ Conditions ◽  
The Mean ◽  
One Year ◽  
Petit Saut ◽  
Potential Inhibitors

ABSTRACT One year after impoundment in January 1994, methanotrophic bacteria in Petit Saut Reservoir (French Guiana) were active at the oxic-anoxic interface. This activity was revealed by the sudden extinction of diffusive methane emission (600 metric tons of CH4 · day−1 for the whole lake surface area, i.e., 360 km2). Lifting of inhibition was suspected. After reviewing the potential inhibitors of this physiological guild (O2, NH4 +, sulfides) and considering the similarities with nitrifiers, we suggest that sunlight influenced the methanotrophic bacteria. On the basis of phospholipid analysis, only a type II methanotrophic community was identified in the lake. Both growth and methanotrophic activity of an enriched culture, obtained in the laboratory, were largely inhibited by illumination over 150 microeinsteins · m−2 · s−1. These results were confirmed on a pure culture of Methylosinus trichosporium OB3B. In situ conditions showed that water transparency was quite stable in 1994 and 1995 and that the oxycline moved steadily deeper until January 1995. Considering the mean illumination profile during this period, we showed that removal of methanotrophic growth inhibition could only occur below a 2-m depth. The oxycline reached this level in October 1994, allowing methanotrophic bacteria to develop and to consume the entire methane emission 4 months later.

Laboratory‐determined transport properties of Berea sandstone

Geophysics ◽  
1985 ◽  
Vol 50 (5) ◽  
pp. 775-784 ◽  
Author(s):  
William D. Daily ◽  
Wunan Lin
Keyword(s):  
Laboratory Data ◽  
Compressional Wave ◽  
Effective Pressure ◽  
Laboratory Measurements ◽  
Berea Sandstone ◽  
Velocity Measurements ◽  
Compressional Wave Velocity ◽  
Intact Sample ◽  
Increasing Temperature

We report laboratory measurements of electrical resistivity ρ, water permeability k, and compressional wave velocity [Formula: see text] for both intact and fractured Berea sandstone samples as functions of temperature from 20°C to 200°C and effective pressure [Formula: see text] from 2.5 MPa to 50 MPa. For the intact sample, [Formula: see text] increases from 3.52 km/s to 4.16 km/s as [Formula: see text] goes from 3 to 50 MPa. With increasing temperature, [Formula: see text] decreases at rates of about 3 percent per 100°C at [Formula: see text] of 5 MPa and about 1.5 percent per 100°C at [Formula: see text] of 38 MPa. Data from the fractured sample are qualitatively similar, but velocities are about 10 percent lower. For both intact and fractured samples, ρ increases less than 15 percent as [Formula: see text] increases from 2.5 MPa to 50 MPa. Although both samples show a larger decrease in resistivity with increasing temperature, most of this change is attributed to the decrease in resistivity of the pore fluid over that temperature range. For both samples, k decreases with increasing pressure and temperature. The intact sample permeability varies from 23 mD at 3 MPa and 20°C to less than 1 mD at 50 MPa and 150°C. The permeability of the fractured sample varies from 676 mD at 3 MPa and 20°C to less than 1 mD at 40 MPa and 190°C. The effect of the fracture on k vanishes after several pressure cycles and above about 100°C. These laboratory data are used to demonstrate the possibility of using resistivity and velocity measurements to estimate in‐situ permeability of a reservoir.

A direct comparison between vibrational resonance and pulse transmission data for assessment of seismic attenuation in rock

Geophysics ◽  
1990 ◽  
Vol 55 (1) ◽  
pp. 51-60 ◽  
Author(s):  
Dane P. Blair
Keyword(s):  
Elastic Scattering ◽  
Wave Attenuation ◽  
Seismic Attenuation ◽  
Experimental Results ◽  
P Wave ◽  
Whole Body ◽  
Frequency Range ◽  
Vibrational Resonance ◽  
Fine Grained ◽  
Pulse Transmission

For the same volume of rock, I compare the attenuation obtained by seismic pulse transmission over the frequency range 1–150 kHz with that obtained by vibrational resonance techniques over the frequency range 1–50 kHz. The initial studies were performed on a rectangular block of medium‐grained granite which was large enough to permit the installation of a seismic pulse transmission array over a 1.8 m path length, yet small enough to permit whole‐body resonance. A Q of 82, for the P wave, was derived from the vibrational resonance results, whereas a Q of 15 was derived from the pulse transmission results. In light of models proposed for the viscoelastic, geometric, and elastic scattering attenuation mechanisms, the experimental results suggest that this large discrepancy in Q values is due to elastic scattering by grain clusters (rather than individual grains) within the granite. Scattering is significant in the high‐frequency pulse transmission tests, but is considered insignificant in the lower frequency resonance tests. Furthermore, this scattering is represented approximately by a constant-Q loss mechanism, which makes it difficult to separate unambiguously elastic scattering and viscoelastic losses. Subsequent studies performed on a large block of fine‐grained norite yield a resonance Q of 89 and a pulse Q of approximately 102 and suggest a negligible scattering loss for this material. The experimental results for the norite imply that the constant-Q theory of seismic pulse attenuation provides a reasonable description of wave attenuation in a dry, fine‐grained crystalline rock over the frequency range 1–150 kHz.

scholarly journals Effectiveness of in situ P-wave measurements in monuments: examples from Greece

2000 ◽  
Vol 22 ◽  
Author(s):  
B. Christaras
Keyword(s):  
Modulus Of Elasticity ◽  
Building Stone ◽  
P Wave ◽  
Mechanical Anisotropy ◽  
Laboratory Measurements ◽  
S Wave ◽  
Wave Velocities ◽  
Wave Measurements ◽  
Made In

P and S wave velocities can be used for both in situ and laboratory measurements of stones. These methods are used for studying such properties as mechanical anisotropy and modulus of elasticity. In this paper, the P-wave velocities were used for the estimation of the depth of weathered or artificially consolidated layers as well as the depth of cracks developed at the surface of the building stone. This estimation was made in relation to the lithology and texture of the materials, given that in many cases different lithological data create similar diagrams. All tests were carried out on representative monuments in Greece.

Laboratory measurements of ultrasonic P‐wave attenuation in partially frozen brines by using sweep signals

2009 ◽  
Author(s):  
Jun Matsushima ◽  
Makoto Suzuki ◽  
Yoshibumi Kato ◽  
Shuichi Rokugawa
Keyword(s):  
Wave Attenuation ◽  
P Wave ◽  
Laboratory Measurements

Determination of formation shear attenuation from dipole sonic log data

Geophysics ◽  
2019 ◽  
Vol 84 (3) ◽  
pp. D73-D79 ◽  
Author(s):  
Qiaomu Qi ◽  
Arthur C. H. Cheng ◽  
Yunyue Elita Li
Keyword(s):  
Reservoir Characterization ◽  
Wave Attenuation ◽  
Synthetic Data ◽  
Low Frequency ◽  
P Wave ◽  
Flexural Wave ◽  
S Wave ◽  
Additional Energy ◽  
Log Data ◽  
Sonic Log

ABSTRACT Formation S-wave attenuation, when combined with compressional attenuation, serves as a potential hydrocarbon indicator for seismic reservoir characterization. Sonic flexural wave measurements provide a direct means for obtaining the in situ S-wave attenuation at log scale. The key characteristic of the flexural wave is that it propagates at the formation shear slowness and experiences shear attenuation at low frequency. However, in a fast formation, the dipole log consists of refracted P- and S-waves in addition to the flexural wave. The refracted P-wave arrives early and can be removed from the dipole waveforms through time windowing. However, the refracted S-wave, which is often embedded in the flexural wave packet, is difficult to separate from the dipole waveforms. The additional energy loss associated with the refracted S-wave results in the estimated dipole attenuation being higher than the shear attenuation at low frequency. To address this issue, we have developed a new method for accurately determining the formation shear attenuation from the dipole sonic log data. The method uses a multifrequency inversion of the frequency-dependent flexural wave attenuation based on energy partitioning. We first developed our method using synthetic data. Application to field data results in a shear attenuation log that is consistent with lithologic interpretation of other available logs.

Sign in / Sign up

Export Citation Format

Share Document