scholarly journals Drill bit noise imaging without pilot trace, a near-surface interferometry example

Solid Earth ◽  
2019 ◽  
Vol 10 (4) ◽  
pp. 1015-1023 ◽  
Author(s):  
Mehdi Asgharzadeh ◽  
Ashley Grant ◽  
Andrej Bona ◽  
Milovan Urosevic
Keyword(s):  
Cross Correlation ◽  
Acoustic Energy ◽  
Seismic Interferometry ◽  
Drill Bit ◽  
Interferometric Imaging ◽  
Near Surface ◽  
Pilot Signal ◽  
Shallow Subsurface ◽  
Drill Bits ◽  
Noise Data

Abstract. Acoustic energy emitted by drill bits can be recorded by geophones on the surface and processed for an image of the subsurface using seismic interferometry methods. Pilot sensors record bit signals on the drill rig and play an important role in processing geophone traces for the image. When pilot traces are not available, traces of the nearest geophone to the rig may be used in deconvolution and cross-correlation of data, but extra signal processing efforts are required to reduce the effect of source signature on cross-correlation results. In this study, we use the seismic interferometry method to image the shallow subsurface beneath a 2-D geophone array by converting geophones to virtual sources. As there is no pilot signal available for this survey, we use the nearest geophone trace for pilot cross-correlation and pilot deconvolution. We modify the spectrum of pilot cross-correlation and deconvolution results so that the effect of source function on virtual data is minimized. We then migrate the virtual shots and compare the results of interferometric imaging with the available image from 3-D (active source) survey and assess the efficiency of our approach. We show that drill bit noise data can be used to generate a reasonably accurate image of the subsurface even in the absence of pilot recordings, but the results should be checked for the appearance of virtual multiples and depth inconsistencies that are caused by errors in the migration velocity.

scholarly journals Drill bit noise imaging without pilot trace, a near surface interferometry example

2019 ◽  
Author(s):  
Mehdi Asgharzadeh ◽  
Ashley Grant ◽  
Andrej Bona ◽  
Milovan Urosevic
Keyword(s):  
Source Function ◽  
Acoustic Energy ◽  
Seismic Interferometry ◽  
Drill Bit ◽  
Interferometric Imaging ◽  
Near Surface ◽  
Pilot Signal ◽  
Shallow Subsurface ◽  
Noise Data ◽  
Interferometry Method

Abstract. Acoustic energy emitted by drill bit can be recorded by geophones on the surface and processed for an image of the subsurface using seismic interferometry methods. Pilot sensors record bit signal on the drill rig and play an important role in processing geophone traces for the image. When pilot traces are not available, traces of the nearest geophone to the rig may be used in deconvolution and crosscorrelation of data but extra signal processing efforts are required to reduce the effect of source signature on crosscorrelation results. In this study, we use seismic interferometry method to image the shallow subsurface beneath a 2D geophone array by converting geophones to virtual sources. As there is no pilot signal available for this survey, we use nearest geophone trace for pilot crosscorrelation and pilot deconvolution. We modify the spectrum of pilot crosscorrelation and deconvolution results so that the effect of source function on virtual data is minimized. We then migrate the virtual shots and compare the results of interferometric imaging with the available image from 3D (active source) survey and assess the efficiency of our approach. We show that drill bit noise data can be used to generate a reasonably accurate image of the subsurface even in the absence of pilot recordings but the results should be checked for appearance of virtual multiples and depth inconsistencies that are caused by errors in the migration velocity.

scholarly journals Denoising ambient seismic field correlation functions with convolutional autoencoders

2019 ◽  
Vol 220 (3) ◽  
pp. 1521-1535
Author(s):  
Loïc Viens ◽  
Chris Van Houtte
Keyword(s):  
Real Time ◽  
Correlation Functions ◽  
Cross Correlation ◽  
Seismic Velocity ◽  
Temporal Evolution ◽  
Seismic Interferometry ◽  
Filter Method ◽  
Near Surface ◽  
Single Station ◽  
Field Correlation

SUMMARY Seismic interferometry is an established method for monitoring the temporal evolution of the Earth’s physical properties. We introduce a new technique to improve the precision and temporal resolution of seismic monitoring studies based on deep learning. Our method uses a convolutional denoising autoencoder, called ConvDeNoise, to denoise ambient seismic field correlation functions. The technique can be applied to traditional two-station cross-correlation functions but this study focuses on single-station cross-correlation (SC) functions. SC functions are computed by cross correlating the different components of a single seismic station and can be used to monitor the temporal evolution of the Earth’s near surface. We train and apply our algorithm to SC functions computed with a time resolution of 20 min at seismic stations in the Tokyo metropolitan area, Japan. We show that the relative seismic velocity change [dv/v(t)] computed from SC functions denoised with ConvDeNoise has less variability than that calculated from raw SC functions. Compared to other denoising methods such as the SVD-based Wiener Filter method developed by Moreau et al., the dv/v results obtained after using our algorithm have similar precision. The advantage of our technique is that once the algorithm is trained, it can be apply to denoise near-real-time SC functions. The near-real-time aspect of our denoising algorithm may be useful for operational hazard forecasting models, for example when applying seismic interferometry at an active volcano.

scholarly journals Acoustic-to-seismic ground coupling: coupling efficiency and inferring near-surface properties

2020 ◽  
Vol 223 (1) ◽  
pp. 144-160
Author(s):  
Artemii Novoselov ◽  
Florian Fuchs ◽  
Goetz Bokelmann
Keyword(s):  
Ground Motion ◽  
Poisson Ratio ◽  
Coupling Efficiency ◽  
Seismic Energy ◽  
Acoustic Energy ◽  
Transfer Coefficients ◽  
Frequency Dependent ◽  
Low Frequencies ◽  
Near Surface ◽  
Shallow Subsurface

SUMMARY A fraction of the acoustic wave energy (from the atmosphere) may couple into the ground, and it can thus be recorded as ground motion using seismometers. We have investigated this coupling, with two questions in mind, (i) how strong it is for small explosive sources and offsets up to a few tens of meters and (ii) what we can learn about the shallow subsurface from this coupling. 25 firecracker explosions and five rocket explosions were analysed using colocated seismic and infrasound sensors; we find that around 2 per cent of the acoustic energy is admitted into the ground (converted to seismic energy). Transfer coefficients are in the range of 2.85–4.06 nm Pa–1 for displacement, 1.99–2.74 μm s–1 Pa–1 for velocity, and 2.2–2.86 mm s−2 Pa–1 for acceleration. Recording dynamic air pressure together with ground motion at the same site allows identification of different waves propagating in the shallow underground, notably the seismic expression of the direct airwave, and the later air-coupled Rayleigh wave. We can reliably infer shallow ground properties from the direct airwave, in particular the two Lamé constants (λ and μ) and the Poisson ratio. Firecrackers as pressure sources allow constraining elastic parameters in the top-most layer. In this study, they provide frequency-dependent values of λ decreasing from 119 MPa for low frequencies (48 Hz) to 4.2 MPa for high frequencies (341 Hz), and μ values decreasing from 33 to 1.8 MPa. Frequency-dependent Poisson ratios ν are in the range of 0.336–0.366.

Preparation of cross-sectional samples for near-surface TEM studies

1987 ◽  
Vol 45 ◽  
pp. 380-381
Author(s):  
R.C. Dickenson ◽  
K.R. Lawless
Keyword(s):  
Standard Sample ◽  
Surface Region ◽  
Specimen Preparation ◽  
Thick Sheet ◽  
Drill Bit ◽  
Sample Holder ◽  
Metal Interface ◽  
Cross Sectional ◽  
Near Surface ◽  
Cold Worked

In thermal oxidation studies, the structure of the oxide-metal interface and the near-surface region is of great importance. A technique has been developed for constructing cross-sectional samples of oxidized aluminum alloys, which reveal these regions. The specimen preparation procedure is as follows: An ultra-sonic drill is used to cut a 3mm diameter disc from a 1.0mm thick sheet of the material. The disc is mounted on a brass block with low-melting wax, and a 1.0mm hole is drilled in the disc using a #60 drill bit. The drill is positioned so that the edge of the hole is tangent to the center of the disc (Fig. 1) . The disc is removed from the mount and cleaned with acetone to remove any traces of wax. To remove the cold-worked layer from the surface of the hole, the disc is placed in a standard sample holder for a Tenupol electropolisher so that the hole is in the center of the area to be polished.

scholarly journals Microanchored borehole fiber optics allows strain profiling of the shallow subsurface

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Cheng-Cheng Zhang ◽  
Bin Shi ◽  
Song Zhang ◽  
Kai Gu ◽  
Su-Ping Liu ◽  
...  
Keyword(s):  
Fiber Optics ◽  
Field Experiments ◽  
Fiber Optic ◽  
Strain Sensing ◽  
Near Surface ◽  
Shallow Subsurface ◽  
Buried Cables ◽  
Capacity Theory ◽  
Confining Pressures ◽  
Strain Determination

AbstractVertical deformation profiles of subterranean geological formations are conventionally measured by borehole extensometry. Distributed strain sensing (DSS) paired with fiber-optic cables installed in the ground opens up possibilities for acquiring high-resolution static and quasistatic strain profiles of deforming strata, but it is currently limited by reduced data quality due to complicated patterns of interaction between the buried cables and their surroundings, especially in upper soil layers under low confining pressures. Extending recent DSS studies, we present an improved approach using microanchored fiber-optic cables—designed to optimize ground-to-cable coupling at the near surface—for strain determination along entire lengths of vertical boreholes. We proposed a novel criterion for soil–cable coupling evaluation based on the geotechnical bearing capacity theory. We applied this enhanced methodology to monitor groundwater-related vertical motions in both laboratory and field experiments. Corroborating extensometer recordings, acquired simultaneously, validated fiber optically determined displacements, suggesting microanchored DSS as an improved means for detecting and monitoring shallow subsurface strain profiles.

Drill‐bit SWD and seismic interferometry for imaging around geothermal wells

2011 ◽  
Author(s):  
Flavio Poletto ◽  
Piero Corubolo ◽  
Biancamaria Farina ◽  
Andrea Schleifer ◽  
Joseph Pollard ◽  
...  
Keyword(s):  
Seismic Interferometry ◽  
Drill Bit ◽  
Geothermal Wells

THEORETICAL STUDIES OF THE VELOCITIES OF THE VIBRATIONS OF DRILL BITS WOODWORKING DRILLING MACHINES

Akustika ◽  
2021 ◽  
pp. 124
Author(s):  
Dmitry Ruslyakov
Keyword(s):  
Sound Pressure ◽  
Natural Frequencies ◽  
Theoretical Studies ◽  
Drill Bit ◽  
Acoustic Models ◽  
Drill Bits ◽  
Sound Pressure Levels ◽  
O 10 ◽  
Noise Spectra

On woodworking machines of the drilling group, drill bits of the following diameters (mm) are used at rotation speeds: SvP2 and SvA-2-ø 50 mm, n = 3000 rpm 4500 rpm; Sv8, Sv12-ø 10-16 mm, n = 2800 rpm; SGVP-ø up to 35 mm, n = 2800 rpm. Acoustic models are described in detail in [1] as can be seen from the analytical dependences of sound pressure levels to calculate the noise spectra, it is necessary to determine the oscillation velocities of the drill bit at their natural frequencies.

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