Estimation of P-Wave Attenuation from High- Resolution Acoustic Data in Water-Saturated Sediments

1997 ◽  
Author(s):  
X.-P. Li
Keyword(s):  
High Resolution ◽  
Wave Attenuation ◽  
P Wave ◽  
Acoustic Data ◽  
Water Saturated

scholarly journals AMPLITUDE-DEPENDENT SPECTRA OF THE DAMPING OF A LONGITUDINAL WAVE IN DRY AND WATER-SATURATED SANDSTONE AT HYDROSTATIC PRESSURE

2018 ◽  
pp. 25-38
Author(s):  
E. I. Mashinskii
Keyword(s):  
Strain Amplitude ◽  
Wave Attenuation ◽  
Confining Pressure ◽  
Dominant Frequency ◽  
P Wave ◽  
Amplitude Dependence ◽  
P Wave Velocity ◽  
Waveform Distortion ◽  
Saturated Sample ◽  
Water Saturated

Data of experimental study of amplitude dependence of P-wave attenuation in the dry and watersaturatedsandstone under confining pressure of 10 MPa are presented. Measurements were conducted on samples  using the reflection method at a dominant frequency of the initial impulse of 1 MHz in the amplitude range   ~ (0,3 – 2,0)  10-6. P-wave attenuation spectra, 1( , ) P Q f  in the frequency range of 0,52 – 1,42  MHz in a dry and saturated sample have an appearance in the form of relaxation peak which depends on  the strain amplitude. In the saturated sandstone, attenuation is greater and the attenuation peak is shifted  to higher frequencies compared to the dry sandstone. With increasing amplitude, wave attenuation  decreases in dry sandstone by 4,5% and in saturated – by 9%. P-wave velocity practically doesn't depend  on the strain amplitude. The possible mechanism of discrete (intermittent) inelasticity which determines the waveform distortion and exerts influence on wave attenuation spectra is discussed. The received results  have fundamental and applied importance for seismics, acoustics and in Earth sciences.

Ultrasonic attenuation in Glenn Pool rocks, northeastern Oklahoma

Geophysics ◽  
1998 ◽  
Vol 63 (2) ◽  
pp. 465-478 ◽  
Author(s):  
Andrew P. Shatilo ◽  
Carl Sondergeld ◽  
Chandra S. Rai
Keyword(s):  
Phase Velocity ◽  
Reservoir Characterization ◽  
Velocity Dispersion ◽  
Wave Attenuation ◽  
Ultrasonic Attenuation ◽  
Clay Content ◽  
P Wave ◽  
Phase Velocity Dispersion ◽  
Q Model ◽  
Water Saturated

Ultrasonic P-wave attenuation and phase velocity dispersion have been estimated for 29 samples of sandstones and 13 samples of shales from a Glenn Pool oil reservoir using a pulse transmission technique. The measurements were performed under effective pressures from atmospheric to 15 MPa. There is a strong correlation between attenuation coefficient and phase velocity dispersion. Even though the observed attenuation may deviate from a “constant Q” model, it generally agrees with a minimum‐phase prediction. Attenuation in the water‐saturated sandstones increases with porosity and permeability. We found no correlation between the attenuation and clay content within the sandstone subset. Attenuation in the shales is much less than that in the sandstones. This difference may be used in reservoir characterization.

Pore fluid effects on S-wave attenuation caused by wave-induced fluid flow

Geophysics ◽  
2012 ◽  
Vol 77 (3) ◽  
pp. L13-L23 ◽  
Author(s):  
Beatriz Quintal ◽  
Holger Steeb ◽  
Marcel Frehner ◽  
Stefan M. Schmalholz ◽  
Erik H. Saenger
Keyword(s):  
Fluid Flow ◽  
Wave Attenuation ◽  
Pore Space ◽  
Seismic Attenuation ◽  
P Wave ◽  
S Wave ◽  
Hydrocarbon Reservoir ◽  
Saturated Media ◽  
Water Saturated ◽  
Wave Induced

We studied seismic attenuation of P- and S-waves caused by the physical mechanism of wave-induced fluid flow at the mesoscopic scale. Stress relaxation experiments were numerically simulated by solving Biot’s equations for consolidation of 2D poroelastic media with finite-element modeling. The experiments yielded time-dependent stress-strain relations that were used to calculate the complex moduli from which frequency-dependent attenuation was determined. Our model consisted of periodically distributed circular or elliptical heterogeneities with much lower porosity and permeability than the background media, which contained 80% of the total pore space of the media. This model can represent a hydrocarbon reservoir, where the porous background is fully saturated with oil or gas and the low-porosity regions are always saturated with water. Three different saturation scenarios were considered: oil-saturated (80% oil, 20% water), gas-saturated (80% gas, 20% water), and fully water-saturated media. Varying the dry bulk and shear moduli in the background and in the heterogeneities, a consistent tendency was observed in the relative behavior of the S-wave attenuation among the different saturation scenarios. First, in the gas-saturated media the S-wave attenuation was very low and much lower than in the oil-saturated or in the fully water-saturated media. Second, at low frequencies the S-wave attenuation was significantly higher in the oil-saturated media than in the fully water-saturated media. The P-wave attenuation exhibited a more variable relative behavior among the different saturation degrees. Based on the mechanism of wave-induced fluid flow and on our numerical results, we suggest that S-wave attenuation could be used as an indicator of fluid content in a reservoir. Additionally, we observed that impermeable barriers in the background can cause a significant increase in S-wave attenuation. This suggests that S-wave attenuation could also be an indicator of permeability changes in a reservoir due to, for example, fracturing operations.

P- and S-wave attenuation logs from monopole sonic data

Geophysics ◽  
2000 ◽  
Vol 65 (3) ◽  
pp. 755-765 ◽  
Author(s):  
Xinhua Sun ◽  
Xiaoming Tang ◽  
C. H. (Arthur) Cheng ◽  
L. Neil Frazer
Keyword(s):  
Wave Attenuation ◽  
Fluid Velocity ◽  
P Wave ◽  
Reservoir Rock ◽  
Rock Properties ◽  
S Wave ◽  
Intrinsic Attenuation ◽  
Modified Method ◽  
Receiver Array ◽  
Attenuation Profiles

In this paper, a modification of an existing method for estimating relative P-wave attenuation is proposed. By generating synthetic waveforms without attenuation, the variation of geometrical spreading related to changes in formation properties with depth can be accounted for. With the modified method, reliable P- and S-wave attenuation logs can be extracted from monopole array acoustic waveform log data. Synthetic tests show that the P- and S-wave attenuation values estimated from synthetic waveforms agree well with their respective model values. In‐situ P- and S-wave attenuation profiles provide valuable information about reservoir rock properties. Field data processing results show that this method gives robust estimates of intrinsic attenuation. The attenuation profiles calculated independently from each waveform of an eight‐receiver array are consistent with one another. In fast formations where S-wave velocity exceeds the borehole fluid velocity, both P-wave attenuation ([Formula: see text]) and S-wave attenuation ([Formula: see text]) profiles can be obtained. P- and S-wave attenuation profiles and their comparisons are presented for three reservoirs. Their correlations with formation lithology, permeability, and fractures are also presented.

Simulation of thermoelastic waves based on the Lord-Shulman theory

Geophysics ◽  
2021 ◽  
Vol 86 (3) ◽  
pp. T155-T164
Author(s):  
Wanting Hou ◽  
Li-Yun Fu ◽  
José M. Carcione ◽  
Zhiwei Wang ◽  
Jia Wei
Keyword(s):  
Thermal Conductivity ◽  
Expansion Coefficient ◽  
Velocity Dispersion ◽  
Wave Attenuation ◽  
Splitting Method ◽  
Grazing Incidence ◽  
P Wave ◽  
Staggered Grid ◽  
Thermal Mode ◽  
P Waves

Thermoelasticity is important in seismic propagation due to the effects related to wave attenuation and velocity dispersion. We have applied a novel finite-difference (FD) solver of the Lord-Shulman thermoelasticity equations to compute synthetic seismograms that include the effects of the thermal properties (expansion coefficient, thermal conductivity, and specific heat) compared with the classic forward-modeling codes. We use a time splitting method because the presence of a slow quasistatic mode (the thermal mode) makes the differential equations stiff and unstable for explicit time-stepping methods. The spatial derivatives are computed with a rotated staggered-grid FD method, and an unsplit convolutional perfectly matched layer is used to absorb the waves at the boundaries, with an optimal performance at the grazing incidence. The stability condition of the modeling algorithm is examined. The numerical experiments illustrate the effects of the thermoelasticity properties on the attenuation of the fast P-wave (or E-wave) and the slow thermal P-wave (or T-wave). These propagation modes have characteristics similar to the fast and slow P-waves of poroelasticity, respectively. The thermal expansion coefficient has a significant effect on the velocity dispersion and attenuation of the elastic waves, and the thermal conductivity affects the relaxation time of the thermal diffusion process, with the T mode becoming wave-like at high thermal conductivities and high frequencies.

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