Exploration Instruments’ Post

Join EEGS for the May TAG webinar “Passive Seismic Approaches for Active Geophysicists”  Tuesday, May 28, 2024  Register at: https://lnkd.in/ez5JvE4D Resonance frequencies are intrinsic properties of elastic media: they depend on their stiffness and mass distribution, and on their constraints.  In geological and geophysical applications, resonance frequencies are traditionally assessed by means of the microtremor H/V seismic method.  Resonance frequencies can quite easily be converted into the corresponding depths of seismic reflectors responsible for the occurrence of those resonances, in the presence of a Vs estimate. Since 1999, this has led to several interesting images of the main reflectors in the soil achieved by means of passive single station approaches.  However, resonances, being intrinsic properties, are expected to change only in amplitude and not in frequency with the measurement point, in a same medium. "How can we reconcile the fact that, as an example, a basin cross-section is a geological medium with characteristic and unique modal frequencies that do not change along the cross-section, with the fact that the H/V peak frequencies shift from the sides to the center of the basin? To answer this question, we’ll explore what we call 1D and 2D resonance and H/V or H&V approaches and provide some hints on how to discriminate and exploit the two cases. 

Excited to share that our work “Smart DAS Uphole Acquisition System: Bridging the Gap Between Surface Seismic and Borehole Geophysics” has been published in the upcoming AGU/Wiley Monograph: Distributed Acoustic Sensing in Borehole Geophysics. Editors: Yingping LI, Robert Mellors, Ge Zhan ISBN: 978-1-394-17924-4 | Publication Date: December 2024 Our innovative system integrates shallow DAS-enabled vertical arrays, improving seismic imaging by enhancing signal-to-noise ratios and reducing flow noise, offering a scalable and cost-effective solution for onshore reservoir monitoring and gas storage. 📚 Pick up a flyer at AGU 2024 or visit the link for more details: 🔗 AGU/Wiley Publication Details 📚 Learn more about TCCS: #DAS #SeismicImaging #BoreholeGeophysics #GeoH2 #SeismicMonitoring #EnergyTransition

This week, as we celebrate Geophysics Day from Argentina, we extend our congratulations to all professionals in this exciting and valuable field of science. We also take this opportunity to invite you to join us for the April session of our 2024 webinar series titled "Shaping Your Seismic": Exploring Exclusion Zones in PaleoScan with Jake Marson. 🔗 Register >> https://lnkd.in/exTQ6WnP #subsurface #geoscience #geophysics

Excited to see one chapter of my PhD study has finally published in Geophysical Prospecting. We showed that the SH-wave full waveform inversion can be used to provide an S-wave velocity model from nine component seismic survey acquired in the Midland Basin. This is normally hard to accomplish from the conventional P-wave seismic survey due to computation cost and parameter trade-off. The S-wave velocity model we built in this study is comparable to the P-wave velocity model derived from the acoustic full waveform inversion. The Vp/Vs ratios trend that is calculated from the SH-wave and P-wave FWI show strong spatial variation that can be used directly to identify organic shale in the Wolfcamp and Spraberry formations. https://lnkd.in/gydbyVA5 Special thanks to Dr. Jim Simmons, Dr. Jihyun Yang for those fruitful discussions and helps.

This is a very insightful publication by highly respected authors. It not only highlights the benefits of enhancing seismic bandwidth but also provides clear explanations of geophysical concepts and key assumptions. https://lnkd.in/ek8c_GqQ

Although I am not at ASEG Discover in Hobart myself, I am excited for the presentation today on “A Novel yet Simple Approach to the Interpretation of HVSR Data in Australia – A Data Rich Case Study from the Pilbara” that I co-authored with Nathan Tabain from BHP. In this work, which is based on a dataset of ~3,400 short-duration 3C passive seismic recordings, Nathan will discuss how not peaks, but resonance troughs were used for interpretation. Indeed, the trough horizon was easier to interpret, had better along-line and across-line continuity, and more vertical variability than the corresponding peak horizon at half the trough frequency. Nathan will bring the proverbial kitchen sink and show how these data correlated, rather spectacularly, with several independent apriori datasets (airborne geophysics and drilling) and interpretations. Extended abstract: https://lnkd.in/d6uFkS8D. Presentation: Thu. 17/10 at 12 noon. Thanks to Alejandro Sanchez and others in the Southern Geoscience Consultants Near Surface team for their processing support, and Aaron Mullineux and crew for the efficient and safe aquisition of the data. The resonance trough example below is from Chandler and Lively (2014): Evaluation of the horizontal-to-vertical spectral ratio (HVSR) passive seismic method for estimating the thickness of quaternary deposits in Minnesota and adjacent parts of Wisconsin. Minnesota Geological Survey, OFR14-01.

New paper as a co-author. Akamatsu et al. (2025, Tectonophysics) "Mesoscale fractures control the scale dependences of seismic velocity and fluid flow in subduction zones" Journal link: https://lnkd.in/gFE-Z5kV Abstract: Natural geological systems contain porosity structures of various scales that play different roles in geophysical properties, fluid flow, and geodynamics. To understand seismic activity associated with high pore-fluid pressure and fluid migration in subduction zones, it is necessary to explore the scale dependence of geophysical properties such as seismic velocity and permeability. Here, we compare laboratory-measured ultrasonic velocity measured on core samples from the Susaki area in the Shimanto accretionary complex, SW Japan, with sonic velocity measured by borehole logging experiments. Results show that P-wave velocity decreases from the laboratory (∼6 km/s) to the borehole scales (∼5 km/s). This scale-variant effect can be explained by a differential effective medium model whereby mesoscale porosity that is undetectable at the ultrasonic wavelength is introduced into the matrix phase with microscale porosity. Assuming typical apertures for micro- and mesoscale fractures, we estimate that the effective permeability can increase to 10^−12 – 10^−11 m^2 with increasing in the mesoscale porosity and decreasing P-wave velocity down to 4–5 km/s. These results indicate that seismic velocity anomalies and related seismic activity are associated with the presence of mesoscale fractures in subduction zones.

🌐 PaleoScan™'s Horizon Stack, Attribute, and Crossplot functionalities enable rapid and accurate analysis of vast amounts of seismic data without compromising the quality or detail of the results - allowing you to focus your expertise on the geology. Join us as we uncover innovative ways to analyze your seismic data. From mastering horizon stacking techniques to leveraging attribute analysis and crossplots, discover how these methods provide new insights into seismic interpretation and reservoir characterization. This webinar will be presented in Spanish by Senior Geophysicist Christian Veltman. 🖥️ Unlocking Your Seismic's Potential: Mastering PaleoScan™'s Horizon Stack, Attributes, and Crossplots (Spanish) 📅 October 3, 2024 ⏲️ 1pm US CDT 🗣️ Spanish Register >> https://lnkd.in/ehySfTm7 #PaleoScan #Geoscience #Subsurface #SeismicInterpretation