It is split into two waves propagating at different speeds, which are polarized in two perpendicular orientations. Shearwave splitting observations and measurements at the. An electric pulse at sonic frequencies is applied to the monopole transmitter to excite compressional and shearwave propagation in the formation. This suggests that the kernels fully capture the complexity of shear wave splitting in heterogeneous anisotropic media and can be. Low levels of seismicity precluded the detection of shearwave splitting values for dataset 2 in the western part of the study area. An extensive borehole seismic program was conducted to calibrate the.
Shearwave splitting analysis crewes research report volume 21 2009 1 numerical modeling of shearwave splitting and azimuthal velocity analysis in fractured media zimin zhang, don c. When stiffness and strength changes have preferential orientations, shear waves undergo birefringence shear wave splitting. The interpretation of shearwave splitting parameters in the presence of two anisotropic layers. Seismic characteristics of two deepwater drilling hazards.
The study is supported by nsf awards ear079015, ear0952064, ear1460516, and. Igor stubailo research engineer reserach engineer at. Automation of shearwave splitting measurements using cluster analysis by n. We have found a very consistent pattern of shearwave splitting in eastern turkey that identification of seismic events in the region. Beneath the peninsular ranges batholith, fast polarization directions parallel the direction of former farallon subduction, suggestive of a slab remnant. Shearwave splitting in the eastern area was measured using dataset 2, yielding approximately ns or nnessw polarization directions. Shear wave splitting applications for fracture analysis. We report a semiautomatic shearwave analysis system, swas, that appears to combine the bene.
Nov 30, 2015 since shear waves are sensitive to a rocks shear modulus, they respond to changes in rock stiffness and strength. Bokelmann and harjes reported the effects on the shear. Shear wave splitting in threedimensional anisotropic media. We apply the method of silver and chart 1991 as modified by. Shear waves swaves are much more sensitive than compressional waves pwaves to the presence of fractures or microfractures and the fluid content within the fracture network.
Pwaves that impinge on an interface at nonnormal incidence can produce swaves, which in that case are known as converted waves. Development of software for processing microseismic data with application to observation of shearwave splitting 76th eage conference and exhibition 2014 2014 nowadays microseismic monitoring technology is widely used for the field control of hydraulic fracturing used in the production of unconventional hydrocarbon and geothermal. As discussed above, seismic waves can propagate at three velocities through an. During this project, i did processing and modeling microearthquake data as follows. Departmentlocation department of earth system sciences of yonsei university, a premier university in korea, located in seoul, south korea. Summary the classical approach to estimating shear wave splitting from vsp data is through layer stripping which can be difficult under complex overburden. Modeling shear wave splitting due to stressinduced anisotropy, with an application to mount asama volcano, japan article in journal of geophysical research.
Numerical modeling of shearwave splitting and azimuthal. Used shear wave splitting and receiver functions methods to understand the crustal and lithospheric mantle structure beneath the western canada sedimentary basin. Shear wave splitting applications for fracture analysis and improved imaging. We present a graphical user interface to facilitate the processing of teleseismic shearwave splitting observations. Based on conventional theories it has been said that the soil structure interaction has effects that are beneficial for the structural response. Steven van benthem cae simulation software lead skf group. Shear wave splitting analysis of local earthquakes is a challenge tackled by a long history of published software. Methodology investigations for shear wave splitting. For stoneley wave acquisition a specific lowfrequency pulse is used. A uniform database of teleseismic shear wave splitting measurements for north america. Seismic shearwave splitting is difficult to measure accurately because of the complexity of the shearwave signal. Shear wave definition is a wave in which the propagated disturbance is a shear strain in an elastic medium. Postprocessing of the combined results of such a project includes a viewer and export option. Along with one colleague, processed seismic data e.
Data from the sonic scanner platform is acquired and ready for solutions through integrated techlog platform workflows for geomechanics, geophysics. Most of the design codes for structures recommends neglecting the effect of ssi in the seismic analysis of the structure. Shearwave splitting in a region with newlyactivated. Shear wave splitting has been studied in many areas of the earth and access to the results of such studies is a valuable tool for geoscientists to understand the structure and dynamics of the earth. Our emphasis lies in the application to teleseismic shearwave splitting analysis, but our code can be. For the a and b classification, it is preferable to measure the shear wave velocity onsite. A professional and passionate geophysicist with 25 years of diverse global industry experience. In anisotropic media, shear waves both monopole refracted and dipole flexural split into orthogonally polarized components having different velocities. Shearwave splitting is frequently used to measure anisotropy in the earth and. Developed and managed rokdocvsp, which contains tools for processing vsps for overburden anisotropy, fracture determination and shear wave splitting analysis. Shear wave splitting occurs for a shear wave traveling through an anisotropic medium shaded. Seismic shear wave anisotropy in the reservoir causes two shear modes to form s 1. The complexity of shear wavearrivals above small earthquakes makes the polarisations and timedelays of shearwave splitting above small earthquakes dif. International handbook of earthquake and engineering seismology, part a.
Shear wave splitting and orientation of the fast shear azimuth guide lateral well placement, and stoneley analysis can indicate and characterize fractures as well as reveal formation mobility. Alongside the functions designed to analyse aspects of elasticity, msat also contains functions to deal with simple aspects of modelling one of the most common seismological observations related to elastic anisotropy, shear wave splitting. More than 40 million people use github to discover, fork, and contribute to over 100 million projects. Similar to birefringence in optics, shearwave splitting occurs whenever a seismic shearwave travels through an anisotropic layer. The earthquake engineering research institute eeri is a leader in dissemination of earthquake engineering research related information both in the u. Philip wild geoscience and software consultant almond.
Shear wave, transverse wave that occurs in an elastic medium when it is subjected to periodic shear. Notes on global shear wave splitting analysis andy nowacki a. A fullfeatured user friendly co2eor and sequestration. However, there is currently no complete solution that integrates manual and partially or fully automatic methods. This provided an opportunity to test automated software in the detection of subtle changes in seismic properties through shear wave splitting analysis and the crosscorrelation of ambient noise. An electric pulse at sonic frequencies is applied to the monopole transmitter to excite compressional and shear wave propagation in the formation. My technical expertise are in high end surface seismic data processing, borehole seismic survey design, acquisition, processing and finally the integration process for advanced reservoir characterization in the most complex basins. Automation of shearwave splitting parameter determination of local. Xuemeng lu software engineer schlumberger linkedin. When incident shear wave arrives at an anisotropic medium, it splits into two shear waves of.
In 2018 he attended the european seismological commission 36th general assembly in malta, where he orally presented our common work on shearwave splitting in attica greece. It can be seen that the match between inverted quantities and the model parameters is excellent. Shearwaves in anisotropic media exhibit birefringence shearwave splitting and travel. In fact, an arbitrarily polarized shear wave will split into two polarized shear wavesone, polarized parallel to the fracture trend faster than the other, as shown in fig. Several case histories, demonstrating the use of shearwave splitting, have been published, and the technology is gaining greater acceptance in the industry. Bestdt3 processing uses sophisticated dispersion correction to give a more accurate true formation shear slowness. In seismology, swaves, secondary waves, or shear waves sometimes called elastic swaves are a type of elastic wave and are one of the two main types of elastic body waves, so named because they move through the body of an object, unlike surface waves swaves are transverse waves, meaning that the oscillations of an swaves particles are perpendicular to the direction of wave propagation.
Shear wave splitting analysis shear wave splitting measurements were made using sks phases and s phases from deep focus earthquakes for which the primary contribution to splitting is expected to come from the upper mantle beneath the recording station e. Since shear waves are sensitive to a rocks shear modulus, they respond to changes in rock stiffness and strength. Matlab seismic anisotropy toolkit using the functions. Intensity techniques for measuring shearwave splitting parameters. Some systems also provide a bmode image in a dual display. Geosciences and geological and petroleum engineering. This paper discusses the specific processing required for a shallowwater converted wave dataset acquired with an ocean bottom cable obc system in the arabian gulf. The method is based on the fact that a shearwave propagating through rocks with stressaligned microcracks will split into two waves, a fast one polarized parallel to the predominant crack direction, and a. Here, we provide an update of the sks splitting databased of becker et al. Automatic measurement of shear wave splitting and applications to.
This study presents shear wave splitting analysis results observed at isp isparta broadband station in the isparta angle, southwestern turkey. Software for teleseismic shearwave splitting analysis. Seismic anisotropy analysis beneath sumatra revealed by shear. Also known as swave, an elastic body wave in which particles oscillate perpendicular to the direction in which the wave propagates. The interpretation of shearwave splitting parameters in. M y current research on shearwave splitting is very interesting given the results that i and others have obtain when analyzing seismic polarization anisotropy in tibet. Splitlab, matlab, shear wave splitting, seismic, splitting, anisotropy, andreas wuestefeld. This can occur also in the presence of fractures in the rock. The shearwave component polarized parallel to the fracture orientation travels with a speed faster than the shearwave component in the perpendicular direction. Shear wave splitting, also called seismic birefringence, is the phenomenon that occurs when a polarized shear wave enters an anisotropic medium. The lesions were located at the center of the elasticity boxes, and the shearwave elastography images of the lesions. Shear wave splitting in the isparta angle, southwestern. Department of geological and mining engineering and sciences. This is based on using the entire waveform as opposed to part of a waveform and look up.
Geology and geophysics shear wave splitting, also called seismic birefringence, is the phenomenon that occurs when a polarized shear wave enters an anisotropic medium fig. Rebollar, shearwave splitting observations at the regions of northern baja california and. When analyzing or designing for a structure that is supported laterally by shear walls, it is important to use the right shear wall analysis software. Integrated java and c tools brought to the company from anitec for modelling anisotropy, fluid substitution and verticalising well velocity data. Shear wave definition of shear wave by merriamwebster. Methodologies for reservoir characterization using fluid. Systematic analysis of shearwave splitting in the aftershock zone of the 1999 chichi, taiwan, earthquake 2331 figure 1. In addition, the shear wave splitting tutorial of savage 1999 and the original publications on the shear wave splitting measurement algorithm silver and chan, 1991 sc91 and the cluster analysis method teanby et al.
A definitive list of earthquake engineering research related shaking tables around the world may be found in experimental facilities for earthquake engineering simulation worldwide. Mantle anisotropy at midocean ridges andy nowacki, michael kendall, james wookey nowacki et al. Fracture density was determined from the analysis of the shearwave splitting, specifically by measuring the time difference between reflections observed in vfast and vslow shear volumes using transform software. In contrast to a fully automated technique, we present a manual, perevent approach that maintains a user control during the sequence of processing. We consider the behaviour of shearwave splitting parameters that are made under the assumption of a single layer of anisotropic material when in fact two layers of differing anisotropic properties are present. Shearwave splitting analysis using simulated annealing exponential figure 2a. Swaves are generated by most land seismic sources, but not by air guns. Figure 4 shows a display of the vfast vslow time difference data in color overlain on a. Shear wave splitting, also called seismic birefringence, is the phenomenon that occurs when a polarized shear wave enters an anisotropic medium fig. Sonic scanner wireline cased hole logging schlumberger.
In addition, istis team of seismologists can provide you with a postprocessing solution to back up the automated system and also more advanced products such as focal mechanisms, moment tensors, shearwave splitting studies, full waveform inversion, doubledifference earthquake locations, and seismic tomography. The dipole transmitters are also driven at low frequency to. Vector fidelity, receiverside shear statics, and compensation for shear wave splitting in the overburden are key topics that had to be addressed in the preprocessing. Shear is the change of shape, without change of volume, of a layer of the substance, produced by a pair of equal forces acting in opposite directions along the two faces of the layer. Shearwave splitting an overview sciencedirect topics. Shear wave definition of shear wave by the free dictionary. Automation of shearwave splitting measurements using.
Vector fidelity, receiverside shear statics, and compensation for shearwave splitting in the overburden are key topics that had to be addressed in the preprocessing. The seismogram viewer tool uses this database to perform the measurement interactively. Inverted results for the interval rotation angles and time delays, which are in the reverse polarity compared to the input model, are shown in figure 1bc respectively. Muhamad riziq maulana jabodetabek, indonesia profil. This paper discusses the specific processing required for a shallowwater convertedwave dataset acquired with an ocean bottom cable obc system in the arabian gulf. Gao abstract shearwave splitting sws analysis using sks, skks, and pks here after collectively called xks phases is one of the most commonly used techniques in. The idea is that when a shearwave enters an anisotropic fractured medium, one shearwave splits into two. We welcome candidates from any fields of seismology including but not limited to probabilistic seismic hazard analysis, seismic waveform inversion, shear wave splitting, and geophysical exploration. Manual for the multiple filter automatic splitting. The dipole transmitters are also driven at low frequency to excite the flexural wave around the borehole. Satisfactory longterm service requires that the saturated concrete be highly resistant to deterioration due to daily or seasonal weather cycles and tidal fluctuations at coastal sites. The building code does allow the design condition to be estimated by a geotechnical engineer, engineering geologist or seismologist, with significant past knowledge of specific geologic formations and conditions considering weathering and fracturing. Shearwave splitting analysis using simulated annealing. Singleevent shear wave splitting techniques remove the effect of splitting by a grid search for the splitting.
Shear wave splitting is typically used as a tool for testing the anisotropy of an area of interest. Developing software package to investigate the effect of fractures on seismic data interpretation of 3d seismic data using seismage total internal software well log analysis estimation of fracture density and orientation by investigating shear wave splitting. Sourceside shearwave splitting provides global comparison of mor anisotropy offaxis splitting is. The result of the shearwave splitting measurement in the sumatra forearc and fault zone. In this case the elastogram overlaid on bmode image is the upper image, whereas the bmode image is the lower image. Making reliable shearwave splitting measurements by kelly h. Figure 4 shows a display of the vfast vslow time difference data in color overlain on a similarity plot. Modeling shear wave splitting due to stressinduced. We present new shear wave splitting data showing systematic lateral variations in uppermantle anisotropy across the plate boundary in southernmost california usa. A location map of the study region with the meishan fault msf, thechelungpu fault clf, and the chukou fault ckf. Dsi dipole shear sonic imager downhole logging schlumberger.
These numbers prove his obvious scientific abilities. We present an automatic shear wave splitting measurement tool for local earthquakes. Shearwave splitting data base we want to faciliate the overview of existing shearwave splitting measurements and share the results of the analysis and experiments with everybody. Alec yates graduate data scientist kantar worldpanel. Development engineer and scientist with strong problem solving skills and over 10 years experience in cuttingedge research, wireless sensor networks, hardware and software innovations, and. Shearwave splitting in azimuthally anisotropic media is sometimes referred to as shearwave birefringence.
The incident shear wave splits into two polarized shear waves fig. This is known as shear wave splitting, shear wave birefringence, or shear wave velocity anisotropy. This is known as shearwave splitting or birefringence a comparison of shearwave splitting with the birefringence of light in crystals is compared in table 5. For shearwave elastography, elastographic im ages were generated without compression, as recommended elsewhere 12. Christos millas professional services and support engineer. Seismic shear wave anisotropy in the reservoir causes two shear modes to form s 1 and s 2 and to propagate with different velocities. Unlike mps, dipole shear is usually derived using receiver array only. We selected 21 good quality seismic events out of nearly 357 earthquakes and calculated splitting parameters polarization direction of fast wave. Our huntsville, al team of consulting engineers, cmt experts, environmental and geotechnical engineers deliver tailored solutions for construction projects. A fullfeatured, user friendly co 2eor and sequestration planning software this project addressed the development of an integrated software solution that includes a graphical user interface, numerical simulation, visualization tools and optimization processes for reservoir simulation modeling of co 2eor. Stewart abstract this report presents the processing and. The topic of my final project is about identification of reservoir fracture distribution and orientation at r geothermal field using shear wave splitting microearthquake method. Worked on an anisotropy measurement project, focusing on the application of an automatic picking code developed by harvard seismology group for shear.
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