Case Study: Ambient seismic noise in an urban environment
Ambient seismic noise in an urban environment: case study using downhole distributed acoustic sensors at the Curtin University campus in Perth, Western Australia
Abstract
Distributed acoustic sensing (DAS) is an emerging technology increasingly employed to monitor changes of formation properties, production noise and micro-seismic activity, and as an array of sensors in active seismic surveys. The data recorded with the DAS systems are very rich; some features observed in DAS records are often not well understood, and thus are underutilised.
A systematic analysis of the data recorded passively with a DAS system in a 900-m deep well over a period of 12 weeks in the Perth metropolitan area, Western Australia, reveals the presence of several types of ambient energy in the subsurface, such as earthquakes, ocean swell and urban noise. In particular, over 85 days of the experiment, the analysis detected sixteen earthquakes, with epicentres ranging from 126 km to 900 km (for the local events) and from 2300 km to 6400 km (for the remote events). Signals with frequencies below 0.9 Hz are dominated by the oceanic swell. The recorded urban noise includes mine blasting, machinery and traffic.
The experiment shows the ability of DAS to detect these events and as such is potentially useful for subsurface characterisation and monitoring.
Publication DOI: https://doi.org/10.1080/08123985.2021.2021802
Dataset DOI: https://doi.org/10.25917/ag5t-vr54
Dataset Download Link: https://cloudstor.aarnet.edu.au/plus/s/nkjAEeYrsRPMaFU
2021 CRGC Annual Meeting
The 2021 Curtin Reservoir Geophysics Consortium Annual Meeting was held in hybrid mode (in-person and online) from the 1st to the 3rd of December over three afternoons from 12:15pm to 6pm.
For further information please visit the CRGC webpage.
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Presentations
Day 1 – 1st December 2021
13:00 13:15 0:15 – Roman Pevzner, Time-lapse seismic signal from small CO2 injection and where to find it: Roman Pevzner, Roman Isaenkov, Sinem Yavuz, Pavel Shashkin, Alexey Yurikov, Konstantin Tertyshnikov, Boris Gurevich, Julia Correa, Stanislav Glubokovskikh, Todd Wood, Barry Freifeld, Paul Barraclough.
13:15 13:40 0:25 – Roman Isaenkov, Advanced time-lapse processing of continuous DAS VSP data for plume evolution monitoring: Roman Isaenkov, Roman Pevzner, Sinem Yavuz, Pavel Shashkin, Alexey Yurikov, Konstantin Tertyshnikov, Boris Gurevich, Julia Correa, Stanislav Glubokovskikh, Todd Wood, Barry Freifeld, Paul Barraclough .
13:40 14:05 0:25 – Alexey Yurikov, Seismic monitoring of CO2 geosequestration using 4D DAS VSP: Alexey Yurikov, Konstantin Tertyshnikov, Roman Isaenkov, Evgenii Sidenko, Sinem Yavuz, Stanislav Glubokovskikh, Paul Barraclough, Pavel Shashkin, and Roman Pevzner.
14:05 14:30 0:25 – Roman Pevzner, Monitoring CO2 injection using direct wave amplitudes and travel times: Roman Pevzner, Stanislav Glubokovskikh, Roman Isaenkov, Pavel Shashkin, Konstantin Tertyshnikov, Sinem Yavuz, Boris Gurevich, Julia Correa, Todd Wood, Barry Freifeld.
14:30 14:55 0:25 – Sinem Yavuz, Monitoring near-surface variations using borehole DAS and SOVs: Sinem Yavuz, Roman Isaenkov, Roman Pevzner, Boris Gurevich, Alexey Yurikov, Pavel Shaskin, Konstantin Tertyshnikov, Julia Correa, Todd Wood, Barry Freifeld.
14:55 15:15 0:20 – Session Discussion.
15:15 15:20 0:05 – Tea Break.
15:20 15:45 0:25 – Konstantin Tertyshnikov, Effects of Cable Deployment Method on DAS VSP Data Quality: Study at CO2CRC Otway in-situ Laboratory: Roman Pevzner, Konstantin Tertyshnikov, Evgenii Sidenko, Sinem Yavuz.
15:45 16:10 0:25 – Evgenii Sidenko, Thermal effects on DAS data caused by water injection: Evgenii Sidenko, Roman Pevzner, Konstantin Tertyshnikov, Maxim Lebedev.
16:10 16:35 0:25 – Evgenii Sidenko, DAS response to changes in reservoir pressure: Evgenii Sidenko, Roman Pevzner, Konstantin Tertyshnikov, Boris Gurevich.
16:35 17:20 0:45 – General Discussion.
Day 2 – 2nd December 2021
13:00 13:25 0:25 – Stanislav Glubokovskikh, Continuous DAS measurements in a deep borehole provides new insights into the generation of the coastal microseisms: Stanislav Glubokovskikh, Roman Pevzner , Evgenii Sidenko , Konstantin Tertyshnikov, Boris Gurevich , Sergey Shatalin , Alexey Slunyaev, Efim Pelinovsky.
13:25 13:50 0:25 – Boris Gurevich, Probing nonlinear elastic properties of the subsurface using seismic waves: Theory & experiment, Boris Gurevich, Valeriya Shulakova, Alexey Yurikov, Roman Pevzner, Konstantin Tertyshnikov.
13:50 14:15 0:25 – Alexey Yurikov, Feasibility of reservoir monitoring using nonlinear seismic effects measured by downhole distributed acoustic sensors: Alexey Yurikov, Roman Isaenkov, Konstantin Tertyshnikov, Boris Gurevich, Evgenii Sidenko, Stanislav Glubokovskikh, Valeriya Shulakova, Barry Freifeld, Julia Correa, Todd Wood and Roman Pevzner.
14:15 14:40 0:25 – Evgenii Sidenko, Feasibility of rapid reverse VSP monitoring of shallow CO2 release: Evgenii Sidenko, Stanislav Glubokovskikh, Konstantin Tertyshnikov, Roman Pevzner.
14:40 15:00 0:20 – Session Discussion
15:00 15:15 0:15 – Tea Break
15:15 15:40 0:25 – Roman Isaenkov, Effects of source mispositioning on VSP data repeatability: Roman Isaenkov, Konstantin Tertyshnikov, Ruben Lopez Lema, Roman Pevzner.
15:40 16:05 0:25 – Sana Zulic, Comparison of amplitude measurements on borehole geophone and DAS data: Sana Zulic, Evgenii Sidenko, Alexey Yurikov, Konstantin Tertyshnikov, Andrej Bona, Roman Pevzner.
16:05 16:50 0:45 – General Discussion.
Day 3 – 3rd December 2021
13:00 13:25 0:25 – Andrej Bona, Land seismic with DAS – update: Andrej Bona, Roman Pevzner, Konstantin Tertyshnikov, Alexey Yurikov, Pavel Shashkin.
13:25 13:50 0:25 – Sana Zulic, Subsurface characterization using Full Waveform Inversion of VSP data: Example from the Curtin GeoLab well: Sana Zulic, Andrej Bona, Konstantin Tertyshnikov, Alexey Yurikov, Roman Pevzner.
13:50 14:15 0:25 – Konstantin Tertyshnikov, Where on Curtin University campus is the dark fibre?: Konstantin Tertyshnikov, Sinem Yavuz, Alexey Yurikov, Roman Isaenkov, Evengii Sidenko, Andrej Bona, Roman Pevzner.
14:15 14:35 0:20 – Session Discussion.
14:35 14:50 0:15 – Tea Break.
14:50 15:15 0:25 – Maxim Lebedev, An apparatus to measure the dynamic Young’s and Shear moduli of rocks at elevated pressures at seismic frequencies: Maxim Lebedev, Vassili Mikhaltsevich.
15:15 15:40 0:25 – Alexey Yurikov, Laboratory measurements with DAS: A fast and sensitive tool to obtain elastic properties at seismic frequencies: Alexey Yurikov, Roman Pevzner, Konstantin Tertyshnikov, Vassili Mikhaltsevitch, Boris Gurevich, Maxim Lebedev.
15:40 16:05 0:25 – Jiabin Liang, Multi-mineral segmentation of micro-tomographic images using a convolutional neural network: Jaibin Liang, Yongyang Sun, Maxim Lebedev, Boris Gurevich, Michel Nzikou, Stephanie Vialle, Stanislav Glubokovskikh.
16:05 16:30 0:25 – Jiabin Liang, High-precision tracking of sandstone deformation from micro-CT images: Jiabin Liang, Maxim Lebedev, Boris Gurevich, Christoph Arns, Stephanie Vialle, Stanislav Glubokovskikh.
16:30 17:15 0:45 – General Discussion.
Curtin/CSIRO Geophysics Group Seminar, 9th September 2021
Probing nonlinear elastic properties of the subsurface using seismic waves: Theory & experiment
Date: Thursday, 9th September, 2021
Time: 10:00 AM – 11:00 AM
Location: CSIRO/ARRC Auditorium, 26 Dick Perry Avenue, Kensington
Presenter: Sana Zulic, Curtin University
Full-waveform inversion (FWI) is a powerful tool for building property images / volumes. It uses the complete seismic wavefield (transmitted, reflected and converted waves) to build the models of subsurface physical properties. We conducted a feasibility study of a 2D elastic FWI applied to synthetic and field single offset vertical seismic profile (VSP) datasets. Even though the coverage of a single offset VSP is limited, and artefacts are observed in the FWI images, a good correlation is demonstrated between VSP migration image, FWI results, gamma-ray log and stratigraphy. We demonstrate that FWI of borehole seismic have potential to give detailed rock properties, at a scale unattainable to seismic reflection methods.
Sana is M.Phil. Student at Curtin University. She is interested in borehole seismic imaging techniques, which can improve the imaging methods for mineral exploration. Her work focuses on optimising vertical seismic profiling survey design and processing workflows to better suit mineral exploration application. She works as a geophysicist at HiSeis.
Curtin/CSIRO Geophysics Group Seminar, 5th August 2021
Distributed Acoustic Sensing for Laboratory Measurements of Elastic Properties at Seismic Frequencies
Date: Thursday, 5th August, 2021
Time: 10:00 AM – 11:00 AM
Location: CSIRO/ARRC Auditorium, 26 Dick Perry Avenue, Kensington
Presenter: Alexey Yurikov, Research Fellow, Exploration Geophysics, Curtin University
Forced-oscillation stress-strain laboratory measurements are increasingly employed to obtain elastic and viscoelastic properties of rocks at seismic frequencies. Yet these measurements are slow and expensive, due in part, to the use of metal or semiconductor strain gauges, which need to be glued to the sample, are fragile, have relatively low sensitivity, and measure very local strain only, so that the measurements can be affected by a slight misalignment of the system assembly and local heterogeneity of the rock. Emergence of fibre-optic distributed acoustic sensing (DAS) technology provides an alternative means of measuring strain.
Strain measurements with DAS involve wounding an optical fibre around the sample multiple times and connecting it to a DAS recording unit. Pilot experiments performed using this setup on samples of Poly(methyl methacrylate) (PMMA), polyether ether ketone (PEEK), aluminium and dry Bentheimer sandstone samples shows good agreement with strain gauge measurements. Advantages of DAS over strain gauges include much higher strain sensitivity (down to 10-11) and signal-to-noise ratio (and hence, shorter time required for measurements), larger dynamic range, ability to measure average (rather than local) strain in the sample, and robustness at elevated temperatures.
Further research is required to obtain independent estimates of Young’s modulus and Poisson’s ratio, and to port the system into a pressure vessel to obtain rock properties at in situ conditions.
Curtin/CSIRO Geophysics Group Seminar, 12th August 2021
Probing nonlinear elastic properties of the subsurface using seismic waves: Theory & experiment
Date: Thursday, 12th August, 2021
Time: 10:00 AM – 11:00 AM
Location: CSIRO/ARRC Auditorium, 26 Dick Perry Avenue, Kensington
Presenter: Valeriya Shulakova, CSIRO
Authors: Boris Gurevich, Valeriya Shulakova, Alexey Yurikov, Roman Pevzner and Konstantin Tertyshnikov
Although exploration seismology is based on linear elasticity, field studies over several decades clearly show seismic effects related to non-linear phenomena. Anomalous non-linearity of rocks may indicate weak or fractured zones, or presence of mixed fluid saturation. We outline theoretical background and give a number of field examples with the aim of exploring these effects using modern seismic acquisition equipment such as fibre-optic sensing.
Curtin/CSIRO Geophysics Group Seminar, 22nd July 2021
Seismic signature of gold mineralisation from rock physics, petrology characterisation and seismic modelling
Date: Thursday, 22nd July, 2021
Time: 10:00 AM – 11:00 AM
Location: ARRC Auditorium, 26 Dick Perry Avenue, Kensington
Presenter: Andre Eduardo C. M. Souza, PhD student, Exploration Geophysics, Curtin University
Abstract
The Most lode gold deposits worldwide are controlled by structures such as shear zones and are commonly associated with characteristic hydrothermal alteration zones when related to particular host rocks. Identifying these indirect indicators of gold mineralization could be used for targeted drilling. Gold deposits are becoming deeper or are hidden by an extensive cover. Therefore, exploratory and mining planning activities require detailed structural imaging to reduce associated drilling costs. Thanks to their capacity to couple resolution and depth of investigation, seismic methods can help extend gold exploration targets to greater depths. However, the seismic survey remains largely speculative in crystalline environments due to: (1) highly complex geologic structures, (2) scarcity of boreholes logs, (3) poor database documenting the elastic properties of rock alterations, (4) ambiguity between strained anisotropic rocks and hydrothermal alteration halos, and (5) lack of quantitative interpretation tools in this type of environment. To better understand the seismic response at gold deposits and to investigate the effects of mineralogy and texture on the seismic properties of gold – hosting rocks, we characterized in the laboratory over 140 core samples representing different stages of alteration and different lithologies, including samples from the shear zone, from two gold mines in Western Australia. Laboratory measurements include densities, porosities, ultrasonic P-and S-wave velocities, textural analysis, and mineralogical characterization. These experimental data were used as input in different rock physics models and forward seismic modelling over a realistic 2D geologic model of the mines to simulate the seismic response. The results indicate that the texture of the host rocks, namely foliation and porosity (even 2%), is the primary control of the seismic properties variation. These results will help to predict the seismic properties of typical alteration zones associated with lode gold deposits, and to infer whether textural changes, mineralogical changes or larger scale structural features will give a response in the seismic signal
Andre is PhD student supported by Curtin University and CSIRO – Deep Earth Imaging Platform. Andre is investigated the effects of mineralogy and texture on seismic signature across hydrothermal alteration zones associated with gold deposition and gold – hosting structures. Along with Andre’s academic skills, he has large experience in Oil & Gas industry as a petroleum geoscientist.
Curtin/CSIRO Geophysics Group Seminar, 15th July 2021
The effect of large scale geo-electrical structures on the inversion of magnetotelluric data
Date: Thursday, 15th July, 2021
Time: 10:00 AM – 11:00 AM
Location: ARRC Auditorium, 26 Dick Perry Avenue, Kensington
Presenter: Rabea Sedaghat, PhD student, Exploration Geophysics, Curtin University
Abstract
One of the major challenges facing interpreters of MT data is the effect of inherent non-uniqueness of inversion outcomes. Large geo-electrical structures beyond the extent of measured data has potential to impact on the outcome of the inversion leading to misinterpretation of target features. One example is TE and TM mode splitting that may result from the extreme contrast in conductivity along crustal scale faulting where there exists a sharp transition from sediment to crystalline basement.
A second example is the sharp geo-electrical contrast that occurs at coastal margins between ocean and land. Additionally, expansive three dimensional near-surface features, such as salt lakes, clay sheets, or flood basalts may all have negative consequences on inversion of MT data, which cannot fully span such features. In this research, we investigate the effect of three large structures including: Darling Fault, Indian Ocean, and shallow conductive features on Riverdale Rd AMT/MT data in Harvey area.
Rabea Sedaghat is a PhD student at Exploration Geophysics, Curtin University. She received a Bachelor of Science in Physics from University of Tehran in 2004 and a MSc in Geophysics in 2009 from Azad University, Science and research Branch, Tehran, Iran. Her principal research interests lie in the field of magnetotelluric and her areas of expertise include magnetotelluric data acquisition, processing, inversion and interpretation; and geomagnetic observatory.
Curtin/CSIRO Geophysics Group Seminar, 1st July 2021
Elemental Analysis via Prompt Gamma Neutron Activation For Diamond Drilling
Date: Thursday, 1st July, 2021
Time: 10:00 AM – 11:00 AM
Location: ARRC Seminar Room, 26 Dick Perry Avenue, Kensington
Presenter: Snezana Petrovic, PhD student, Exploration Geophysics, Curtin University
Abstract
The purpose of this research project is to conceptually design, and test the idea of a prompt gamma neutron activation (PGNA) logging-while-drilling tool that would reliably identify the elemental composition of rock units. The principle idea is to place a PGNAA system onto or behind the core-tube assembly. This configuration will allow us to gather data about the rock mass while drilling diamond core holes, which is the most widely used drilling method in mineral exploration and development. As the core is retrieved every 1.5 to 3m at a time the data can be stored in the tool and retrieved every time core is extracted. This near real-time elemental analysis could provide information that would improve almost every stage of mining and mineral processing.
Logging while drilling (LWD) is a technique that involves recording data from various sensors while the borehole is being drilled. Currently, elemental assay and petrophysical information is provided after the hole has been completed; often weeks afterwards. The key advantage in real time measurement is the possibility of making drilling decisions immediately when needed. Also, the borehole conditions during drilling are usually better compared to wireline logging; there is less drilling fluid invasion than during the logging (Crain’s Petrophysical Handbook). Although the LWD technique is in widespread use in oil and gas industry since the late 1980s, it has not been adopted in mining industry due to the lack of suitable tools. Australian scientists claim that adapting this method will improve efficiency and cut cost in mineral exploration industry (Mehta 2009).
Prompt Gamma Neutron Activation Analysis (PGNAA) offers a means to perform elemental analysis while drilling. It is a penetrative, non-destructive analytical method used for determining the presence and amount of many elements in the sample simultaneously. PGNAA is particularly suitable for borehole logging due to its large sampling volume (an order of magnitude greater sample than core assay, thus, statistically robust) and real-time analysis potential. This technique employs a neutron source as the main source of radiation. When the emitted neutrons enter a medium, they collide with nuclei in rock until they lose energy and slow down. Once “thermalised” various elemental nuclei capture these thermalized neutrons, producing unstable compound nucleus in excited state, which decays by the nearly instantaneous emission of one or more gamma rays (Molnár and SpringerLink 2004). The emitted gamma-rays have energies characteristic of the target nuclei, and measuring the relative intensities at various energies (spectral gamma analysis) with a gamma ray detector we may identify the neutron-capturing elements. Thus, neutron induced gamma ray spectrum analysis may be used to compute elemental concentrations in the rock in-situ..
Snezana Petrovic is a PhD candidate at the Discipline of Exploration Geophysics at Curtin University. Her research interests in developing a prototype of a prompt gamma neutron activation logging-while-drilling tool for slim-holes in mineral exploration. She received her B.Sc. and M.Sc. (2014) in Applied Geophysics from the Faculty of Mining and Geology, University of Belgrade (Serbia).
LinkedIn profile: https://www.linkedin.com/in/snezanapetrovic90/