Compressional Wave Attenuation Research Articles

Permeability effects on the seismic response of gas reservoirs

In this work, we analyse the role of permeability on the seismic response of sandstone reservoirs characterized by patchy gas-water saturation. We do this in the framework of Johnson′s model, which is a generalization of White′s seminal model allowing for patches of arbitrary geometry. We first assess the seismic attenuation and velocity dispersion characteristics in response to wave-induced fluid flow. To this end, we perform an exhaustive analysis of the sensitivity of attenuation and velocity dispersion of compressional body waves to permeability and explore the roles played by the Johnson parameters T and S/V, which characterize the shape and size of the gas-water patches. Our results indicate that, within the typical frequency range of exploration seismic data, this sensitivity may indeed be particularly strong for a variety of realistic and relevant scenarios. Next, we extend our analysis to the corresponding effects on surface-based reflection seismic data for two pertinent models of typical sandstone reservoirs. In the case of softer and more porous formations and in the presence of relatively low levels of gas saturation we observe that the effects of permeability on seismic reflection data are indeed significant. These prominent permeability effects prevail for normal-incidence and non-normal-incidence seismic data and for a very wide range of sizes and shapes of the gas-water patches. For harder and less porous reservoirs, the normal-incidence seismic responses exhibit little or no sensitivity to permeability, but the corresponding non-normal-incidence responses show a clear dependence on this parameter, again especially so for low gas saturations. The results of this study therefore suggest that, for a range of fairly common and realistic conditions, surface-based seismic reflection data are indeed remarkably sensitive to the permeability of gas reservoirs and thus have the potential of providing corresponding first-order constraints.

Fast compressional wave attenuation and dispersion due to conversion scattering into slow shear waves in randomly heterogeneous porous media

Within the viscosity-extended Biot framework of wave propagation in porous media, the existence of a slow shear wave mode with non-vanishing velocity is predicted. It is a highly diffusive shear mode wherein the two constituent phases essentially undergo out-of-phase shear motions (slow shear wave). In order to elucidate the interaction of this wave mode with propagating wave fields in an inhomogeneous medium the process of conversion scattering from fast compressional waves into slow shear waves is analyzed using the method of statistical smoothing in randomly heterogeneous poroelastic media. The result is a complex wave number of a coherent plane compressional wave propagating in a dynamic-equivalent homogeneous medium. Analysis of the results shows that the conversion scattering process draws energy from the propagating wave and therefore leads to attenuation and phase velocity dispersion. Attenuation and dispersion characteristics are typical for a relaxation process, in this case shear stress relaxation. The mechanism of conversion scattering into the slow shear wave is associated with the development of viscous boundary layers in the transition from the viscosity-dominated to inertial regime in a macroscopically homogeneous poroelastic solid.

A measurement system for shear speed using interface wave dispersion.

Our recent work has highlighted the effect of shear on the dispersion of acoustic normal modes. Recently, Pierce et al. showed the effect of shear on compressional wave attenuation and its frequency dependence. Potty and Miller [(2010)] showed that sediment shear speed can significantly impact compressional modal arrival times near the Airy phase. We have observed that neglecting shear in compressional wave speed inversions results in a bias in our long range sediment tomography inversions. All of these factors emphasize the importance of estimating shear wave speeds in semiconsolidated shallow water sediments. One of the most promising approaches to estimate shear speed is to invert the shear speed profile using the dispersion of seismoacoustic interface waves (Scholte waves) that travel along the sediment-water boundary. The propagation speed and attenuation of the Scholte wave are closely related to shear-wave speed and attenuation over a depth of one to two wavelengths into the seabed. A shear measurement system being developed at the University of Rhode Island based on this concept will be presented. Test data collected on land will be shown and preliminary analysis techniques will be discussed. [Work supported by the Office of Naval Research.]

Seismic wave attenuation beneath the Australasian region

The attenuation of seismic waves is strongly influenced by temperature and rheological changes, and so provides an important supplement to information from seismic wavespeeds. Differential attenuation measurements are made for seismic waves refracted through the mantle beneath the Australasian region and are then used to construct 3D images of the attenuation of shear and compressional waves. The differential attenuation between different seismic phases is estimated using a spectral ratio method in the frequency band 0.25–1.0 Hz using a multi-taper method. Over this band the attenuation is nearly independent of frequency so that the logarithmic spectral ratio is a linear function of frequency. Differential measurements are made either between P and S phases on the same record or between stations for P and S waves separately. Images of seismic attenuation for the Australasian region are produced using a tomographic inversion, with the fast marching method employed to trace ray paths in an initial 3-D model derived from surface wave tomography. There is a deep seated horizontal contrast between central Australia and the eastern seaboard. The crustal and lithospheric mantle beneath the Archean and Proterozoic rocks in the west and in the middle of the continent have low seismic attenuation, whereas the Phanerozoic material in the east is more attenuative. Regions with recent volcanism, most likely associated with hot spots such as near Bass Strait and the Coral Sea, display high seismic attenuation anomalies. There is a strong contrast in attenuation between the relatively low loss lithosphere and the high loss asthenosphere beneath with a change by a factor of 6–10. Anisotropy in attenuation is slight even though some would be expected from the radial anisotropy seen in shear wavespeed in the lithosphere.

Numerical analysis of wave-induced fluid flow effects on seismic data: Application to monitoring of CO2storage at the Sleipner field

[1] In this work we analyze how patchy distributions of CO2 and brine within sand reservoirs may lead to significant attenuation and velocity dispersion effects, which in turn may have a profound impact on surface seismic data. The ultimate goal of this paper is to contribute to the understanding of these processes within the framework of the seismic monitoring of CO2 sequestration, a key strategy to mitigate global warming. We first carry out a Monte Carlo analysis to study the statistical behavior of attenuation and velocity dispersion of compressional waves traveling through rocks with properties similar to those at the Utsira Sand, Sleipner field, containing quasi-fractal patchy distributions of CO2 and brine. These results show that the mean patch size and CO2 saturation play key roles in the observed wave-induced fluid flow effects. The latter can be remarkably important when CO2 concentrations are low and mean patch sizes are relatively large. To analyze these effects on the corresponding surface seismic data, we perform numerical simulations of wave propagation considering reservoir models and CO2 accumulation patterns similar to the CO2 injection site in the Sleipner field. These numerical experiments suggest that wave-induced fluid flow effects may produce changes in the reservoir's seismic response, modifying significantly the main seismic attributes usually employed in the characterization of these environments. Consequently, the determination of the nature of the fluid distributions as well as the proper modeling of the seismic data constitute important aspects that should not be ignored in the seismic monitoring of CO2 sequestration problems.

Effect of Partial Water Saturation on Attenuation Characteristics of Low Porosity Rocks

Keywords Wave attenuation Partial water saturation Compressional wave Longitudinal wave Low porosityrock1 IntroductionWith the advance of geophysical exploration techniques, insitu measurements on elastic wave velocities have beensuccessfully employed for investigating near-surface anddeep geological structures. However, in situ techniques thatmeasure the attenuation of elastic waves are still in theirinfancy due to the difficulty of calibration, the lack oftheoretical models, and the inaccuracy of field scale mea-surements. While attenuation itself is strongly related toimportant physical characteristics of porous media, such aspore fluid composition, stress states, and internal hetero-geneity (Johnston et al. 1979), the understanding of theattenuation characteristics of porous media is still limited.The rocks are frequently exposed to water through rainor ground water. The presence of pore water not only playsan important role from an engineering perspective, but alsosignificantly alters acoustic wave propagation. Compres-sional wave velocity changes little until the pore spaces arefully saturated with water because the air in partially sat-urated pore fluids diminishes the stiffness of the pore fluidsand hardly contributes to strengthening the rock frame. Onthe other hand, when there is an increase in water satura-tion, the compressional wave attenuation—that is related toenergy dissipation—tends to increase more sensitively thanvelocity (Gardner et al. 1964; Toks}oz et al. 1979; Mavkoand Nur 1979; Murphy 1982; Winkler and Nur ;Cadoret et al. 1998).Several previous researchers have investigated the fluideffect on the wave velocity and attenuation, mainlyfocusing on high porosity rocks (mostly greater than 20%of porosity), such as limestone (Cadoret et al. 1998) andsandstone (Murphy 1982; Winkler and Nur ). Thisstudy, therefore, examines how water saturation affects theattenuation characteristics of low porosity rocks. The effectof partial water saturation on the attenuation is explored byrecapitulating Biot model and by conducting a series oflaboratory tests. Then, the results of Biot model and lab-oratory tests are compared and some implications arediscussed.2 Recapitulation of Biot Model: Partial WaterSaturation Effect on AttenuationBiot model (Biot 1956a, b) can be applied to porous media,particularly for modeling wave velocity and attenuation ofa rock. Biot model assumes that pore fluids flow only in thedirection parallel to the direction of the wave propagationand that the viscous fluid motion follows Poiseuille flow ina cylindrical tube. No chemical, electrical, or thermal

Studies on the effect of shear on compressional wave dispersion.

The results of a study to examine the effect of shear on compressional wave dispersion are presented. Modal arrival time data from different shallow water sites will be analyzed to examine the influence of shear. The modal travel times corresponding to the Airy Phase regions are extremely sensitive to shear. Simple inversion schemes will be developed to estimate the shear speed in the sediment by comparing theoretical predictions with experimental data. The estimated shear speeds will also be compared with shear speeds calculated from core data. The effect of shear on compressional wave attenuation will also be investigated. Synthetic data will be generated for elastic bottom, with different shear speeds, and these data will be inverted for compressional wave attenuation. One of the most promising approaches to estimate shear speed is to invert the relation between seismo‐acoustic interface waves (Scholte waves) that travel along boundaries between media and shear wave speed. The propagation speed and attenuation of the Scholte wave are closely related to shear‐wave speed and attenuation over a depth of 1‐2 wavelengths into the seabed. A shear measurement system being developed at the University of Rhode Island based on this concept will be presented. [Work supported by the Office of Naval Research.]

Anisotropic dispersion and attenuation due to wave‐induced fluid flow: Quasi‐static finite element modeling in poroelastic solids

Heterogeneous porous media such as hydrocarbon reservoir rocks are effectively described as anisotropic viscoelastic solids. They show characteristic velocity dispersion and attenuation of seismic waves within a broad frequency band, and an explanation for this observation is the mechanism of wave‐induced pore fluid flow. Various theoretical models quantify dispersion and attenuation of normal incident compressional waves in finely layered porous media. Similar models of shear wave attenuation are not known, nor do general theories exist to predict wave‐induced fluid flow effects in media with a more complex distribution of medium heterogeneities. By using finite element simulations of poroelastic relaxation, the total frequency‐dependent complex stiffness tensor can be computed for a porous medium with arbitrary internal heterogeneity. From the stiffness tensor, velocity dispersion and frequency‐dependent attenuation are derived for compressional and shear waves as a function of the angle of incidence. We apply our approach to the case of layered media and to that of an ellipsoidal poroelastic inclusion. In the case of the ellipsoidal inclusion, compressional and shear wave modes show significant attenuation, and the characteristic frequency dependence of the effect is governed by the spatiotemporal scale of the pore fluid pressure relaxation. In our anisotropic examples, the angle dependence of the attenuation is stronger than that of the velocity dispersion. It becomes clear that the spatial attenuation patterns show specific characteristics of wave‐induced fluid flow, implying that anisotropic attenuation measurements may contribute to the inversion of fluid transport properties in heterogeneous porous media.

Application of the BISQ model to clay squirt flow in reservoir sandstones

An understanding of the variations of compressional wave velocity and attenuation in sandstones as a function of pore‐fluid properties is important for the identification and monitoring of hydrocarbon reservoirs. In order for seismic inversion to be well constrained a rock physics model that describes accurately the observed behavior is required; a number of such models have been proposed but have not been extensively tested against laboratory data. The unified Biot and squirt flow model was applied to data obtained from ultrasonic experiments conducted on a wide range of sandstone types when saturated with different pore fluids with viscosities ranging from 0.3 to 1000 cP. This model was seen to match well all the observed velocity and attenuation values as opposed to the Biot model, which was only successful for clean sandstones saturated with low viscosity fluids. This has led to the conclusion that a squirt flow mechanism is important at the grain scale. In addition, an increase in the dynamic uniaxial strain modulus of the dry frame with increasing pore‐fluid viscosity was observed. In the absence of free gas or grain contact microcracks (the laboratory data were collected at 60 MPa effective pressure), this can be linked to decreasing local flow and decreasing relaxation in the soft pore space of the sandstone, the extent of which is in turn connected to the clay content and pore structure of the sandstone. These results imply that at ultrasonic frequencies the squirt‐flow is due to the presence of clay.

Plastic yielding as a frequency and amplitude independent mechanism of seismic wave attenuation

We have developed a mathematical formulation of two mechanisms of compressional wave attenuation, which can occur within the solid rock frame prestressed up to its yield stress in part of its volume. Energy losses are attributed to two distinct processes: irreversible plastic yielding and formation of radial microfractures around microscopic cavities. Small-amplitude waves propagating through the rocks prestressed at their yield point would cause nonelastic strain to avoid building local stresses above the yield limit and attenuate some fraction of their energy per every loading cycle. New mechanisms of microscale yielding and microfracturing give rise to frequency-independent attenuation due to rate-independence of plasticity formulation. Quality factor [Formula: see text] predicted by the model is independent of strain amplitude for small strains and decreases with increasing amplitude for large strains. We found that attenuation can be high even for small seismic strains [Formula: see text]. Thus, [Formula: see text] is achieved at effective pressures greater than twice the yield strength of the solid matrix for the plastic yielding mechanism and at overpressures exceeding half tensile strength for microfracturing.

Comments on “On pore fluid viscosity and the wave properties of saturated granular materials including marine sediments” [J. Acoust. Soc. Am. 122, 1486–1501 (2007)

The ability of the grain shearing (GS) and viscous grain shearing (VGS) models to relate geophysical and acoustic properties is tested by a method based on the claimed tight coupling between compressional and shear wave speeds and attenuations, which allows the test result to be quantified in a single parameter. The VGS model is claimed to provide a better fit to the measured sound speed and attenuation in sandy sediments below 10 kHz. In situ measurements of wave speeds and attenuations from the Sediment Acoustics Experiment 1999 (SAX99) and published laboratory measurements by Prasad and Meissner [Geophysics 57, 710-719 (1992)] on a number of sand samples were used to test the models. By this metric, the SAX99 data show that the VGS model is no better than the original GS model because the improved agreement of compressional wave speeds at low frequencies is achieved at the expense of gross overestimation of the shear wave attenuation. When applied to the measurements by Prasad and Meissner, it is shown that the GS models are not applicable at any significant confining pressures, and at zero pressure they may only be applicable to a small subset of the sand samples.

Studies on the effect of shear on compressional wave attenuation.

Results of a modeling study to examine the effect of shear on compressional wave attenuation are presented. This study also investigates a shear inversion algorithm based on interface waves using synthetic data. Recent studies suggest that inclusion of shear speed is necessary to explain the correct frequency dependence of attenuation. Synthetic data will be generated for elastic bottom, with different shear speeds, and these data will be inverted for compressional wave attenuation. This could provide insight into the effect of shear speed on the attenuation coefficient obtained from inversion at various frequencies. In addition to investigating this effect, we also develop inversion algorithms for shear speed. One of the most promising approaches is to invert the relation between seismo-acoustic interface waves (Scholte waves) that travel along boundaries between media and shear wave speed. The propagation speed and attenuation of the Scholte wave are closely related to shear-wave speed and attenuation over a depth of 1–2 wavelengths into the seabed. The dispersion characteristics of the Scholte wave has been successfully used for inversion of sediment shear properties. Synthetic data will be used in our study to develop an inversion scheme. [Work supported by Office of Naval Research.]

Measurement of Low-Frequency Sound Attenuation in Marine Sediment

Marine sediment compressional wave attenuation and its frequency dependence have been active topics in the ocean acoustics community. To support the predictions of the frequency dependence of the sediment attenuation, experimental studies are essential for providing the observations of the sediment attenuation as a function of frequency in different environments, such as sediment type, source-receiver range, water depth, etc. This paper proposes an experimental method for estimating marine sediment attenuation at low frequencies in shallow water. The experimental geometry is short range between a vertical line array and multiple source depths to cover bottom reflections over a wide span of grazing angles. Single bounce bottom-reflected (BR) and sub-bottom-reflected signals are used in the analysis to obtain the best approximation of the sediment intrinsic attenuation. The attenuation estimating method is demonstrated on chirp data (1.5-4.5 kHz) collected on the New Jersey Continental Shelf during the 2006 Shallow Water Experiment (SW06). The data indicate a linear frequency dependence of the compressional wave attenuation for clay rich sediments on the outer shelf, and the estimated value is 0.15 dB/? within the frequency band of 1.75-3.15 kHz. The observation of small sound-speed dispersion of ~ 15 m/s over the frequency band is consistent with a linear frequency dependence of attenuation.

Simultaneous Laboratory Measurement of Acoustic and Hydraulic Properties of Unsaturated Soils

Complete sets of acoustic properties (compressional and shear wave velocities and attenuations) and hydraulic properties (the soil water characteristic curve and the unsaturated hydraulic conductivity function) were determined across a full range of water contents for two types of soil specimens. The acoustic and hydraulic data were collected using a novel device developed at the University of Vermont. The acoustic data were collected using a Kelly wavelet with a center frequency of 20 kHz. The measured acoustic velocities and attenuations across a full range of water contents were consistent with similar measurements found in the literature and made in rock specimens. The experimental data reported here can be used to verify analytical models that attempt to link acoustic and hydraulic properties of unconsolidated and unsaturated porous media.

Seismic modeling of multidimensional heterogeneity scales of Mallik gas hydrate reservoirs, Northwest Territories of Canada

In hydrate‐bearing sediments, the velocity and attenuation of compressional and shear waves depend primarily on the spatial distribution of hydrates in the pore space of the subsurface lithologies. Recent characterizations of gas hydrate accumulations based on seismic velocity and attenuation generally assume homogeneous sedimentary layers and neglect effects from large‐ and small‐scale heterogeneities of hydrate‐bearing sediments. We present an algorithm, based on stochastic medium theory, to construct heterogeneous multivariable models that mimic heterogeneities of hydrate‐bearing sediments at the level of detail provided by borehole logging data. Using this algorithm, we model some key petrophysical properties of gas hydrates within heterogeneous sediments near the Mallik well site, Northwest Territories, Canada. The modeled density, and P and S wave velocities used in combination with a modified Biot‐Gassmann theory provide a first‐order estimate of the in situ volume of gas hydrate near the Mallik 5L‐38 borehole. Our results suggest a range of 528 to 768 × 106 m3/km2 of natural gas trapped within hydrates, nearly an order of magnitude lower than earlier estimates which did not include effects of small‐scale heterogeneities. Further, the petrophysical models are combined with a 3‐D finite difference modeling algorithm to study seismic attenuation due to scattering and leaky mode propagation. Simulations of a near‐offset vertical seismic profile and cross‐borehole numerical surveys demonstrate that attenuation of seismic energy may not be directly related to the intrinsic attenuation of hydrate‐bearing sediments but, instead, may be largely attributed to scattering from small‐scale heterogeneities and highly attenuate leaky mode propagation of seismic waves through larger‐scale heterogeneities in sediments.

Physical and Acoustic Properties of Gas-bearing Sediments in Jinhae Bay, the South Sea of Korea

High-resolution seismic survey and sediment core sampling were conducted to investigate acoustic characteristics of gas-bearing sediments in Jinhae Bay, the southeast of Korea. The sediment in Jinhae Bay is mostly homogenous mud deposited after the Holocene transgression. Along with the 410 km of chirp seismic profiling, five piston core samples were collected on the track lines. Gassy sediments are common and occur widely in the bay. Core samples were analyzed for sediment texture, physical properties (porosity, water content, bulk density, and grain density), acoustic properties (compressional wave velocity and attenuation), and electrical resistivity. X-radiograph image analysis was also performed to observe the shape of degassing cracks. There is no significant downcore variation on physical and sediment textures regardless of existence of gas bubbles. However, compressional wave velocity dramatically decreases from average 1480 to 1380∼739 m/s for the cores that penetrate the gas-bearing zones. This is probably due to degassying cracks that developed by escaping gases and free gas bubbles that are still trapped in the cores. Electrical resistivity is the only geotechnical property that increases in the gas-bearing zone where compressional wave velocity abruptly decreases. This indicates the possibility of using both electrical resistivity as an index variable as well as to compressional wave velocity to identify gassy sediment microstructure because there are little changes in texture and composition of sediment.

Estimating marine sediment attenuation at low frequency with a vertical line array

This paper presents a method of determining the compressional wave attenuation in marine sediment from a short range measurement. The data were collected on a vertical line array at a range of 230 m during the Shallow Water 2006 experiments. The sediment attenuation is extracted from the signal strength ratio of the sea bottom reflection to a sub-bottom reflection at different frequencies from 1.75 to 3.15 kHz. Linear frequency dependence of the attenuation is found from the estimation. The sediment attenuation estimate is lower than the values estimated from the inversions of acoustic field data previously done in the vicinity.

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

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.

Statistical characterization of gas-patch distributions in partially saturated rocks

Reservoir rocks are often saturated by two or more fluid phases forming complex patterns on all length scales. The objective of this work is to quantify the geometry of fluid phase distribution in partially saturated porous rocks using statistical methods and to model the associated acoustic signatures. Based on X-ray tomographic images at submillimeter resolution obtained during a gas-injection experiment, the spatial distribution of the gas phase in initially water-saturated limestone samples are constructed. Maps of the continuous variation of the percentage of gas saturation are computed and associated binary maps obtained through a global thresholding technique. The autocorrelation function is derived via the two-point probability function computed from the binary gas-distribution maps using Monte Carlo simulations.The autocorrelation function can be approximated well by a single Debye correlation function or a superposition of two such functions. The characteristic length scales and show sensitivity (and hence significance) with respect to the percentage of gas saturation. An almost linear decrease of the Debye correlation length occurs with increasing gas saturation. It is concluded that correlation function and correlation length provide useful statistical information to quantify fluid-saturation patterns and changes in these patterns at the mesoscale. These spatial statistical measures are linked to a model that predicts compressional wave attenuation and dispersion from local, wave-induced fluid flow in randomly heterogeneous poroelastic solids. In particular, for a limestone sample, with flow permeability of 5 darcies and an average gas saturation of [Formula: see text], significant [Formula: see text]-wave attenuation is predicted at ultrasonic frequencies.

Amplitude‐frequency dependencies of wave attenuation in single‐crystal quartz: Experimental study

The experiments have been conducted to investigate the effect of strain amplitude and frequency on the compressional and shear wave attenuation in quartz samples of three types: the intact quartz, fractured quartz, and smoky quartz. The measurements were performed using the reflection method on a pulse frequency of 1 MHz with changing strain in the range 0.3 ≤ ɛ ≤ 2.0 μstrain under a confining pressure of 10 MPa and at ambient temperature. The essential difference in amplitude‐frequency characteristics of wave attenuation in three quartz types has been detected. The intact quartz shows the more “simple” behavior in comparison with the fractured and smoky quartz. The attenuation (the inverse quality factor Q) depends on strain amplitude as Q−1(ɛ) ∼ ɛ−n, where n ≅ 0.005–0.085, with the greatest decrease in the smoky and fractured quartz reaching of about 15%. Relaxation spectra of attenuation are presented in the frequency range from 0.4 to 1.4 MHz. The dependence Qp−1(f) ∼ f−1.2 characterizes the intact and fractured quartz, whereas the smoky quartz has the relaxation peak. The dependence Qs−1(f) ∼ f−0.84 presents S wave relaxation spectrum in the intact quartz; in the fractured and smoky quartz, the attenuation peaks take place. The strain amplitude variation exerts influence on the relaxation strength, the peak frequency, and the width of the relaxation peak. Such behavior of attenuation can be explained by a joint action of viscoelastic and microplastic mechanisms. These results can be considered as a contribution for providing the experimental background to the theory of attenuation in rocks. They can also be used in solving applied problems in material science, seismic prospecting, etc.