scholarly journals A Computer-Controlled Ultrasound Pulser-Receiver System for Transskull Fluid Detection using a Shear Wave Transmission Technique

2007 ◽  
Vol 54 (9) ◽  
pp. 1772-1783 ◽  
Author(s):  
Sai Tang ◽  
Gregory Clement ◽  
Kullervo Hynynen
Keyword(s):  
Shear Wave ◽  
Wave Transmission ◽  
Transmission Technique ◽  
Receiver System ◽  
Computer Controlled ◽  
Fluid Detection

A new method for shear‐wave logging

Geophysics ◽  
1980 ◽  
Vol 45 (10) ◽  
pp. 1489-1506 ◽  
Author(s):  
Chōrō Kitsunezaki
Keyword(s):  
Shear Wave ◽  
Single Point ◽  
External Pressure ◽  
Borehole Wall ◽  
S Wave ◽  
Neutral Buoyancy ◽  
Wave Characteristics ◽  
Sonic Log ◽  
Receiver System ◽  
Filter Tube

Reliable evaluation of shear (S) wave characteristics in boreholes may be facilitated by the system proposed here, in a wide variety of geologic conditions and depths. The measurements can be done with a sonde, suspended freely in water contained in a borehole. The main part of the sonde consists of a source, a filter tube, and receivers. In this system, the wave field is treated approximately as that in an infinite homogeneous solid medium, because the wavelength is sufficiently longer than the borehole diameter. The source behaves as a single point force. The direct S‐wave is detected on a line (borehole axis) perpendicular to the force axis, in which pre‐dominant radiation of shear wave is expected. This fact is completely different from some modified systems of sonic log, in which (shear wave) is the converted‐refracted wave propagating as the shear wave along a borehole wall. The proposed source system is the (indirect‐excitation type), wherein the force is applied to a borehole wall indirectly through a pressure distribution of doublet‐type excited in the water. Based on its principle, this source system eliminates generation of dilatational noise waves and also assures operation at greater depths because no work is done against the external pressure, as a whole, at the source. The proposed receiver system is the suspension type, wherein horizontal motion of the borehole wall (ground motion of S‐wave) is detected through corresponding water motion by a detector of neutral buoyancy. The fundamental applicability of this logging system was confirmed by experiments at shallow depths.

On the source-frequency dependence of fracture-orientation estimates from shear-wave transmission experiments

2015 ◽  
Vol 114 ◽  
pp. 81-100 ◽  
Author(s):  
Leo K. Santos ◽  
J.J.S. de Figueiredo ◽  
Bode Omoboya ◽  
Jörg Schleicher ◽  
Robert R. Stewart ◽  
...  
Keyword(s):  
Frequency Dependence ◽  
Shear Wave ◽  
Wave Transmission ◽  
Fracture Orientation

Shear wave speed imaging using unfocused plane wave transmission

2013 ◽  
Vol 3 (4) ◽  
pp. 242-249 ◽  
Author(s):  
Jeong Man Park ◽  
Sung Jae Kwon ◽  
Mok Kun Jeong
Keyword(s):  
Plane Wave ◽  
Shear Wave ◽  
Wave Speed ◽  
Wave Transmission ◽  
Shear Wave Speed

Characterizing the borehole response for single-well shear-wave reflection imaging

Geophysics ◽  
2020 ◽  
pp. 1-42
Author(s):  
Yang-Hu Li ◽  
Xiao-Ming Tang ◽  
Huan-Ran Li ◽  
Sheng-Qing Lee
Keyword(s):  
Shear Wave ◽  
Wave Reflection ◽  
Spherical Wave ◽  
Dipole Source ◽  
Virtual Source ◽  
Shear Wave Imaging ◽  
Receiver System ◽  
Wave Imaging ◽  
Single Well ◽  
Reflection Imaging

Single-well shear-wave imaging using a dipole source-receiver system is an important application for detecting geological structures away from the borehole. This development allows for determining the azimuth information of the structures. Existing analyses, however, focus on the data received at the borehole axis and use the elastic reciprocity theorem to model the borehole radiation and recording. We extend the existing analyses to model the radiation, reflection, and the recording response of the borehole for azimuthally spaced receivers off the borehole axis. By treating the mirror image of the borehole source with respect to the reflector plane as a virtual source, the borehole reception problem is shown to be equivalent to the response of the borehole to the spherical wave incidence from the virtual source, which can be solved using the cylindrical-wave expansion method. An asymptotic solution using the steepest decent method is obtained if the virtual source is far from the borehole. The analytical solution allows us to analyze the borehole response for azimuthally spaced off-axis receivers. The analysis results agree well with those from 3D finite-difference simulations. With this analysis, one can further model the multi-component shear-wave reflection data from the cross-dipole acoustic tool and study the azimuthal variation characteristics of the data. The results show that, while the data characteristics are dominated by those of a dipole, non-dipole responses due to the off-axis reception can be observed, the magnitude of the responses depending on the off-axis distance and frequency and on the formation elasticity. The non-dipole response characteristics have the potential to resolve the 180°-ambiguity problem in the azimuth determination for the dipole shear-wave imaging. The findings, therefore, provide new information to the shear-wave reflection imaging analysis and development.

scholarly journals Maximizing the energy of surface wave and diminishing the effect of lateral inhomogenousness in the multichannel analysis of the surface wave (MASW)

2019 ◽  
Vol 2 (5) ◽  
pp. 105-112
Author(s):  
Ngan Nhat Kim Nguyen ◽  
Luu Van Do ◽  
Van Thanh Nguyen ◽  
Trinh Phuc Tran ◽  
Khuong Manh Vo
Keyword(s):  
Surface Wave ◽  
Shear Wave ◽  
Wave Velocity ◽  
Shear Wave Velocity ◽  
Phase Curve ◽  
Clay Layer ◽  
Spectral Image ◽  
Near Surface ◽  
Multichannel Analysis ◽  
Receiver System

Multichannel analysis of surface wave (MASW) is one of the novel seismic methods in geophysic field in Vietnam. MASW is able to survey the stiffness of the soil environment under the ground via the shear-wave velocity VS by analyzing the spectral image of surface wave. We did the 1D MASW survey upon the borehole belonged to the residential development project at district 2, Ho Chi Minh city with fixed receiver system, different source orientations and different source offsets. The spectral images of surface wave were combined to maximize the surface wave’s energy on the spectral image of surface wave to minimize the effect of lateral inhomogenousness and near - far source offsets. The data points were chosen on the phase curve on spectral image of surface wave for the inversion process to define shear wave velocity VS. The VS from MASW was compared to the petrographic components and another seismic method (downhole). The relative difference of the obtained VS values between two methods was less than 10%. The change of VS in MASW was absolutely compatible to petrographic components in geological borehole, near surface filled soil layer (93 m/s), dark-gray silty layer (68–157 m/s), sandy clay layer (250–265 m/s) and lower clay layer (254–400 m/s).

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