Time-lapse monitoring of stress-field variations within the Lower Permian shales in Kansas

2020 ◽  
Vol 39 (5) ◽  
pp. 318-323 ◽  
Author(s):  
Sarah L. Morton ◽  
Richard D. Miller ◽  
Julian Ivanov ◽  
Shelby L. Peterie ◽  
Robert L. Parsons
Keyword(s):  
Surface Wave ◽  
Stress Field ◽  
Shear Wave ◽  
Time Lapse ◽  
Bulk Velocity ◽  
Low Velocity ◽  
Mining Operations ◽  
South Central ◽  
Cap Rock ◽  
Velocity Variations

Azimuthal stress-field variations in Permian shale overlying voids in salt appear related to localized void roof failure based on interpretations of time-lapse recordings of passive seismic surface-wave data. Salt-dissolution voids in south-central Kansas exist within the Hutchinson Salt Member as a result of solution mining operations early in the 20th century. Since shear-wave velocity can be estimated from surface-wave analysis and is directly related to the shear modulus, or material rigidity, it can be used to indicate shale cap-rock competency. Temporal bulk-velocity variations in bedrock acquired over a known void from 2013 to 2018 are consistent with cyclic stress-field behavior expected with repetitive localized failure within the shale cap rock. It was determined that roof failure and associated subsidence began prior to the 2013 surveys along a north–south failure plane with consistent progression from southwest to northeast until 2017. A low-velocity anomaly observed in 2014–2015 on both profiles indicated a load redistribution in the shale cap rock. This low-velocity region was gradually replaced by an increasing velocity field in subsequent years. These bulk-velocity variations are interpreted as representations of stoping, which occurs when overlying roof layers or sidewall segments progressively fail. As of 2018, the velocity trend in the affected area remained lower than the recorded baseline conditions, with no low-velocity anomalies observed since 2015. Shear-wave velocities are not likely to return to 2013 conditions due to loss of roof material and redistribution of load. Annual surveys will monitor for conditions consistent with the beginning of a stress buildup and roof collapse unless monitoring indicates a change in the subsurface that warrants invasive analysis or other actions.

scholarly journals Tackling Lateral Variability Using Surface Waves: A Tomography-Like Approach

2021 ◽  
Author(s):  
Ilaria Barone ◽  
Jacopo Boaga ◽  
Alberto Carrera ◽  
Adrian Flores-Orozco ◽  
Giorgio Cassiani
Keyword(s):  
Inverse Problem ◽  
Surface Wave ◽  
Weighted Least Squares ◽  
Low Velocity ◽  
Lateral Velocity ◽  
Linear Inversion ◽  
Urban Waste ◽  
Near Surface ◽  
Velocity Variations ◽  
Waste Deposit

AbstractLateral velocity variations in the near-surface reflect the presence of buried geological or anthropic structures, and their identification is of interest for many fields of application. Surface wave tomography (SWT) is a powerful technique for detecting both smooth and sharp lateral velocity variations at very different scales. A surface-wave inversion scheme derived from SWT is here applied to a 2-D active seismic dataset to characterize the shape of an urban waste deposit in an old landfill, located 15 km South of Vienna (Austria). First, the tomography-derived inverse problem for the 2-D case is defined: under the assumption of straight rays at the surface connecting sources and receivers, the forward problem for one frequency reduces to a linear relationship between observed phase differences at adjacent receivers and wavenumbers (from which phase velocities are straightforwardly derived). A norm damping regularization constraint is applied to ensure a smooth solution in space: the choice of the damping parameter is made through a minimization process, by which only phase variations of the order of the average wavelength are modelled. The inverse problem is solved for each frequency with a weighted least-squares approach, to take into account the data error variances. An independent multi-offset phase analysis (MOPA) is performed using the same dataset, for comparison: pseudo-sections from the tomography-derived linear inversion and MOPA are very consistent, with the former giving a more continuous result both in space and frequency and less artefacts. Local dispersion curves are finally depth inverted and a quasi-2-D shear wave velocity section is retrieved: we identify a well-defined low velocity zone and interpret it as the urban waste deposit body. Results are consistent with both electrical and electromagnetic measurements acquired on the same line.

scholarly journals The Polito Surface Wave flat-file Database (PSWD): statistical properties of test results and some inter-method comparisons

2021 ◽  
Vol 19 (6) ◽  
pp. 2343-2370
Author(s):  
Federico Passeri ◽  
Cesare Comina ◽  
Sebastiano Foti ◽  
Laura Valentina Socco
Keyword(s):  
Surface Wave ◽  
Shear Wave ◽  
Wave Velocity ◽  
Shear Wave Velocity ◽  
Active Surface ◽  
Statistical Properties ◽  
Test Results ◽  
Flat File ◽  
Research Fields ◽  
Database Content

AbstractThe compilation and maintenance of experimental databases are of crucial importance in all research fields, allowing for researchers to develop and test new methodologies. In this work, we present a flat-file database of experimental dispersion curves and shear wave velocity profiles, mainly from active surface wave testing, but including also data from passive surface wave testing and invasive methods. The Polito Surface Wave flat-file Database (PSWD) is a gathering of experimental measurements collected within the past 25 years at different Italian sites. Discussion on the database content is reported in this paper to evaluate some statistical properties of surface wave test results. Comparisons with other methods for shear wave velocity measurements are also considered. The main novelty of this work is the homogeneity of the PSWD in terms of processing and interpretation methods. A common processing strategy and a new inversion approach were applied to all the data in the PSWD to guarantee consistency. The PSWD can be useful for further correlation studies and is made available as a reference benchmark for the validation and verification of novel interpretation procedures by other researchers.

Azimuthal multiple signal classification of dispersive and aliased surface waves recorded in 3D seismic acquisition

Geophysics ◽  
2021 ◽  
pp. 1-84
Author(s):  
Chunying Yang ◽  
Wenchuang Wang
Keyword(s):  
Surface Wave ◽  
Surface Waves ◽  
Body Waves ◽  
Signal Classification ◽  
Dispersion Pattern ◽  
Velocity Spectrum ◽  
Low Velocity ◽  
Surface Wave Dispersion ◽  
Multiple Signal Classification ◽  
Multiple Signal

Irregular acquisition geometry causes discontinuities in the appearance of surface wave events, and a large offset causes seismic records to appear as aliased surface waves. The conventional method of sampling data affects the accuracy of the dispersion spectrum and reduces the resolution of surface waves. At the same time, ”mode kissing” of the low-velocity layer and inhomogeneous scatterers requires a high-resolution method for calculating surface wave dispersion. This study tested the use of the multiple signal classification (MUSIC) algorithm in 3D multichannel and aliased wavefield separation. Azimuthal MUSIC is a useful method to estimate the phase velocity spectrum of aliased surface wave data, and it represent the dispersion spectra of low-velocity and inhomogeneous models. The results of this study demonstrate that mode-kissing affects dispersion imaging, and inhomogeneous scatterers change the direction of surface-wave propagation. Surface waves generated from the new propagation directions are also dispersive. The scattered surface wave has a new dispersion pattern different to that of the entire record. Diagonal loading was introduced to improve the robustness of azimuthal MUSIC, and numerical experiments demonstrate the resultant effectiveness of imaging aliasing surface waves. A phase-matched filter was applied to the results of azimuthal MUSIC, and phase iterations were unwrapped in a fast and stable manner. Aliased surface waves and body waves were separated during this process. Overall, field data demonstrate that azimuthal MUSIC and phase-matched filters can successfully separate aliased surface waves.

Three-Dimensional Simulations of Strong Ground Motion in the Shidian Basin

2014 ◽  
Vol 501-504 ◽  
pp. 1447-1452
Author(s):  
Yan Yan Yu ◽  
Qi Fang Liu
Keyword(s):  
Surface Wave ◽  
Ground Motion ◽  
Seismic Waves ◽  
Three Dimensional ◽  
Spectral Element ◽  
Low Velocity ◽  
Computing Technique ◽  
Soil Deposits ◽  
Basin Edge ◽  
The Impact

Seismic response of the Shidian basin to moderate scenario earthquake is investigated considering 3D basin model incorporated with real topography by using the spectral-element method and parallel computing technique. The wave propagation process, the generation of surface wave, and the impact of soil deposits velocity to the basin-induced surface wave are studied in this paper. The results show that the amplification behavior of the basin is the interactions of basin geometry and low velocity soil deposits. First, locally small hollows in the basin are apt to trap seismic waves and produce much stronger ground motion, basin edge and areas with deep sediments are also characterized with large amplification. Then, basin with softer soil deposits produces stronger surface waves with lower propagation velocity and higher mode.

scholarly journals Relationship between Shear Wave Velocity and SPT-N Value for Residual Soils

2018 ◽  
Vol 203 ◽  
pp. 04009
Author(s):  
Nor Faizah Bawadi ◽  
Nur Jihan Syamimi Jafri ◽  
Ahmad Faizal Mansor ◽  
Mohd Asri Ab Rahim
Keyword(s):  
Surface Wave ◽  
Shear Wave ◽  
Wave Velocity ◽  
Shear Wave Velocity ◽  
Soil Profile ◽  
Dynamic Parameter ◽  
Kuala Lumpur ◽  
Residual Soils ◽  
Standard Penetration Testing ◽  
Wave Methods

The shear wave velocity (Vs) is an important dynamic parameter in the field of geotechnical engineering. One of the surface wave methods is Spectral Analysis of Surface Wave (SASW) has received attention in obtaining the shear wave velocity (Vs) profile by analysing the dispersion curve. SASW is a non-destructive test, fast and time-effective for field survey. Thus, this paper proposed the application of SASW method to obtain the shear wave velocity (Vs) to represent the soil profile. This paper aims to determine the shear wave velocity (Vs) profile using SASW method, where the testing has been conducted at three site of residual soils located in Damansara, Kuala Lumpur and Nilai area. In this study, it shows that the soil profile obtained from shear wave velocity value is similar pattern with profile that obtained using Standard Penetration Testing (SPT), which conventional used in field. The shear wave velocity are proportionally increase with depth.

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