A Study on Characteristics of Seismic Attenuation by Using Spectral Ratio Method

2014 ◽  
Vol 51 (5) ◽  
pp. 687-695 ◽  
Author(s):  
Jin-woo Lee ◽  
Ji-ho Ha ◽  
Hwi-Kyung Ko ◽  
Woo-Keen Chung ◽  
Sung-ryul Shin
Keyword(s):  
Spectral Ratio ◽  
Seismic Attenuation ◽  
Ratio Method ◽  
Spectral Ratio Method

Integrated estimation of interval-attenuation profiles

Geophysics ◽  
2006 ◽  
Vol 71 (4) ◽  
pp. A19-A23 ◽  
Author(s):  
James Rickett
Keyword(s):  
Reservoir Characterization ◽  
Spectral Ratio ◽  
Seismic Attenuation ◽  
Ratio Method ◽  
Amplitude Analysis ◽  
Linear Inversion ◽  
Amplitude Spectra ◽  
Initial Spectrum ◽  
Spectral Ratio Method ◽  
Attenuation Profiles

Quantitative estimates of seismic attenuation are useful for a variety of applications, ranging from seismic-acquisition design, to seismic processing, amplitude analysis, and reservoir characterization. I frame the estimation of interval attenuation from a set of seismic wavelets as a linear inversion of their log-amplitude spectra. The initial spectrum at the first depth location and a set of depth-varying amplitude scalers are estimated simultaneously with an effective-attenuation [Formula: see text] profile. The algorithm can be regarded as a tomographic extension of the spectral-ratio method that uses all the information available in the amplitude spectra, appropriately weighted so that estimates are not biased by noise. Constraints can be applied to ensure the [Formula: see text] values vary smoothly, and solving for log [Formula: see text] rather than [Formula: see text] ensures only positive attenuation values. Tests on synthetic and field data illustrate the trade-off between vertical resolution and sensitivity to noise. A covariance study indicates that improvements in interval-attenuation estimates over the traditional spectral-ratio method come from systematic-noise handling and the explicit constraints on [Formula: see text], rather than the fact that the inversion ties the log-spectral data together with a single estimate of the spectrum at the first depth location.

scholarly journals Double-difference seismic attenuation tomography method and its application to The Geysers geothermal field, California

2021 ◽  
Vol 225 (2) ◽  
pp. 926-949
Author(s):  
Hao Guo ◽  
Clifford Thurber
Keyword(s):  
Spectral Ratio ◽  
Geothermal Field ◽  
Seismic Attenuation ◽  
Double Difference ◽  
Ratio Method ◽  
Moderate Degree ◽  
Attenuation Structure ◽  
The Geysers ◽  
Spectral Ratio Method ◽  
Tomography Method

SUMMARY Knowledge of attenuation structure is important for understanding subsurface material properties. We have developed a double-difference seismic attenuation (DDQ) tomography method for high-resolution imaging of 3-D attenuation structure. Our method includes two main elements, the inversion of event-pair differential ${t^*}$ ($d{t^*}$) data and 3-D attenuation tomography with the $d{t^*}$ data. We developed a new spectral ratio method that jointly inverts spectral ratio data from pairs of events observed at a common set of stations to determine the $d{t^*}$ data. The spectral ratio method cancels out instrument and site response terms, resulting in more accurate $d{t^*}$ data compared to absolute ${t^*}$ from traditional methods using individual spectra. Synthetic tests show that the inversion of $d{t^*}$ data using our spectral ratio method is robust to the choice of source model and a moderate degree of noise. We modified an existing velocity tomography code so that it can invert $d{t^*}$ data for 3-D attenuation structure. We applied the new method to The Geyser geothermal field, California, which has vapour-dominated reservoirs and a long history of water injection. A new Qp model at The Geysers is determined using P-wave data of earthquakes in 2011, using our updated earthquake locations and Vp model. By taking advantage of more accurate $d{t^*}$ data and the cancellation of model uncertainties along the common paths outside of the source region, the DDQ tomography method achieves higher resolution, especially in the earthquake source regions, compared to the standard tomography method using ${t^*}$ data. This is validated by both the real and synthetic data tests. Our Qp and Vp models show consistent variations in a normal temperature reservoir that can be explained by variations in fracturing, permeability and fluid saturation and/or steam pressure. A prominent low-Qp and Vp zone associated with very active seismicity is imaged within a high temperature reservoir at depths below 2 km. This anomalous zone is likely partially saturated with injected fluids.

Seismic Attenuation Estimation Using an Enhanced Log Spectral Ratio Method

2022 ◽  
pp. 1-1
Author(s):  
Naihao Liu ◽  
Shengtao Wei ◽  
Yang Yang ◽  
Shengjun Li ◽  
Fengyuan Sun ◽  
...  
Keyword(s):  
Spectral Ratio ◽  
Seismic Attenuation ◽  
Ratio Method ◽  
Spectral Ratio Method ◽  
Attenuation Estimation

Seismic attenuation estimation using the modified log spectral ratio method

2018 ◽  
Vol 159 ◽  
pp. 386-394 ◽  
Author(s):  
Naihao Liu ◽  
Bo Zhang ◽  
Jinghuai Gao ◽  
Zhaoqi Gao ◽  
Shengjun Li
Keyword(s):  
Spectral Ratio ◽  
Seismic Attenuation ◽  
Ratio Method ◽  
Spectral Ratio Method ◽  
Attenuation Estimation

scholarly journals Event couple spectral ratio Q method for earthquake clusters: application to North-West Bohemia

2018 ◽  
Author(s):  
Marius Kriegerowski ◽  
Simone Cesca ◽  
Matthias Ohrnberger ◽  
Torsten Dahm ◽  
Frank Krüger
Keyword(s):  
Wave Attenuation ◽  
Attenuation Factor ◽  
Source Region ◽  
Spectral Ratio ◽  
Ratio Method ◽  
Earthquake Swarms ◽  
North West ◽  
High Attenuation ◽  
West Bohemia ◽  
Spectral Ratio Method

Abstract. We develop an amplitude spectral ratio method for event couples from clustered earthquakes to estimate seismic wave attenuation (Q−1) in the source volume. The method allows to study attenuation within the source region of earthquake swarms or aftershocks at depth, independent of wave path and attenuation between source region and surface station. We exploit the high frequency slope of phase spectra using multitaper spectral estimates. The method is tested using simulated full wavefield seismograms affected by recorded noise and finite source rupture. The synthetic tests verify the approach and show that solutions are independent of focal mechanisms, but also show that seismic noise may broaden the scatter of results. We apply the event couple spectral ratio method to North-West Bohemia, Czech Republic, a region characterized by the persistent occurrence of earthquake swarms in a confined source region at mid-crustal depth. Our method indicates a strong anomaly of high attenuation in the source region of the swarm with an averaged attenuation factor of Qp 

Measuring the sediment thickness in urban areas using revised H/V spectral ratio method

2019 ◽  
Vol 260 ◽  
pp. 105223 ◽  
Author(s):  
Baoqing Tian ◽  
Yanan Du ◽  
Zhiwei You ◽  
Ruohan Zhang
Keyword(s):  
Urban Areas ◽  
Spectral Ratio ◽  
Ratio Method ◽  
Sediment Thickness ◽  
Spectral Ratio Method
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