4th EAGE Workshop on Fiber Optic Sensing for Energy Applications
- Conference date: August 14-15, 2024
- Location: Perth, Australia
- Published: 14 August 2024
1 - 20 of 30 results
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The Application of Distributed Acoustic Sensing for the Location of Microseismic Events Associated with Longwall Mining
More LessAuthors T. Dean, M. Henderson, R. Czarny, J. Du Toit, G. Goldswain and A. CarmenateSummaryLongwall coal mining involves a section or ‘panel’ of the seam, roughly 300 m wide, being mined continuously by a shearer which moves backwards and forwards across the coal face. The shearer is protected from the roof collapsing above it by supports. As mining progresses the roof collapses behind the supports, forming the ‘Goaf’. Microseismic monitoring of longwall panels, although in no way routine, has been the subject of several studies aimed at improving safety through identification of possible rockburst or coal and/or gas outburst (where rocks/coal/gas are uncontrollable ejected/injected into the mine workings). Another potential issue is periodic (or cyclic) weighting, when strong units in the roof cantilever over the goaf. Usually geophones are placed within the mine workings due to ease of access but also occasionally within boreholes ( Hatherly et al. 1995 , Luo and Hatherly 1998 ). The number of geophones that can be deployed in each hole is limited and therefore Distributed Acoustic Sensing (DAS) is attractive as it offers the ability to sense the full length of the borehole as well as any sections of cable that are deployed on the surface ( Luo and Duan 2021 ).
In this paper we describe a
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Long-range DAS-VSP Trials at Curtin GeoLab Facility
More LessAuthors R. Pevzner, O. Collet and K. TertyshnikovSummaryAcquisition of borehole seismic data using distributed acoustic sensing (DAS) technology is a rapidly developing trend in borehole geophysics. This includes active VSP surveys for the subsurface characterisation and active and passive surveys for reservoir monitoring. While an increasingly popular technique onshore, time-lapse DAS VSP is still relatively rare in offshore environments as, among other challenges, it often requires going through long umbilical cables to the well.
Recently, some solutions to this problem have emerged. For instance, one approach involves adding passive components, like separate cores on tie-back cables, to transmit and receive pulses to and from the sensing fibre.
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Monitoring Pressure Communication for Fault-Stability Assessment at CO2 Storage Sites Using Distributed Fiber Optic Strain Sensing(DFOSS)
More LessAuthors R. Amer, Z. Xue and T. HashimotoSummaryIn this study, distributed fiber optic strain sensing (DFOSS) was employed in a monitoring well with a depth of 750 meters within a Water-Alternating-Gas Injection field. Over 19 months, we monitored water production/ injection from various production layers at different depths and from different production wells at monitoring distances ranging from 1 to 5.5 kilometers. Our findings demonstrate successful strain capture using DFOSS, affirming its capability to monitor pressure communication within a 5.5-kilometer diameter area. This technology holds promise for CO2 storage site applications as a cost-effective tool, especially when deployed between the injector and adjacent faults within the area of review to evaluate faults stability and ensure CO2 injection sites safety.
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Surface-DAS Seismic Acquisition Experiment using Various Types of Fiber Optic Cable at the Aquistore CCS Site
More LessAuthors H. Shimizu, N. Shimoda, H. Tanaka, T. Kobayashi, Y. Konishi, D. White, Z. Movahedzadeh, E. Nichel, M. Mondanos and A. StorkSummaryA field experiment of the DAS seismic acquisition using various fiber optic cables (FOCs) buried at approximately 50 cm depth in the surface ground was conducted at the Aquistore CCS site in November 2023. The primary purpose is to evaluate the seismic responses of the linear cable and the custom-made helically wound cable (HWC). The total length of the cable was almost 5 km, comprising four kinds of FOCs spliced in series to form a single loop: 1) a 30-degree HWC, 2) a linear FOC, 3) a 60-degree HWC, and 4) a lead-in FOC. The active sources consisted of dynamite sources and a permanent rotary seismic source. Inspection of the acquired shot records shows that the acquired data generally have good quality. Further analysis will focus on the variation of seismic response with the incident angle and azimuth.
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Monitoring Shallow CO2 Release with Time-lapse VSP and DAS Seismic Techniques
More LessAuthors V. Shulakova, K. Tertyshnikov, R. Isaenkov, B. Gurevich, O. Collet and R. PevznerSummaryA controlled CO2 release test involving the injection of 38 tonnes of CO2 into a fault zone between 336–342 m depth over four days was conducted successfully at CSIRO In-Situ Laboratory, Western Australia, in February 2019. The experiment aimed to assess the detection and monitoring of shallow CO2 accumulations. Seismic monitoring, employing offset vertical seismic profiling (VSP) and distributed acoustic sensing (DAS), conducted eight consecutive surveys during CO2 injection.
To verify complete CO2 release, a ninth VSP survey resembling previous surveys was conducted in March 2023. However, modifications in DAS system acquisition parameters for the last dataset posed challenges during seismic time-lapse data processing.
The study showcases a successful time-lapse processing workflow and highlights the reliability of a monitoring system with fiber optic sensors, enabling detection and observation of injected CO2 and its complete release or dissolution over time.
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A Deep Learning Approach for Microseismic Detection with Downhole DAS
More LessAuthors E. Al-Hemyari, O. Collet, K. Tertyshnikov and R. PevznerSummaryDistributed Acoustic Sensing (DAS) enables efficient seismic data acquisition for permanent and passive micro-seismic monitoring, especially using permanent downhole installations. However, acquiring large amounts of data pushes against the limits of existing computational systems and algorithms, especially for continuous passive seismic monitoring applications. Thus, more than ever, novel methods to analyse big data are required. In this abstract, we investigate using a supervised deep learning neural network to detect and locate microseismic events due to CO2 injection. The challenges of using synthetic data to train the neural network were identified and addressed to fill the gap in the context of a microseismic application. The methodology was demonstrated on synthetic data and tested on data from the Otway CO2 injection site. More tests were performed to confirm the observed effects of including time shifts in the training data. Those enlightening results pave the way for a more extensive study and potential applications to more field data.
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Inferring Wet Microseismic Events by Frac-hits in Hydraulic Fracturing
More LessSummaryUnconventional hydraulic fracturing of oil and gas causes rock fracture, with some energy being diffused via microseismic waves. However, the deformation of non-fractured rocks also radiates microseismic waves. Therefore, there are multiple solutions for describing artificial fracture by microseismic events during hydraulic treatment. This article studies that the deployment of optical fibers and microseismic recievers in the same observation well, fiber optic technology can accurately identify the frac-hit of fracturing fluid reaching the wellbore. We use spatiotemporal properties to determine the corresponding microseismic events, and explore the characteristics of wet events by analyzing the stress drop of microseismic events. Based on those, we selected effective microseismic events, optimize the dimensions of artificial fracture networks, and enhance the support effect of microseismic guidance on hydraulic fracturing.
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High-resolution Downhole DAS Data Acquisition with Electric Sparker
More LessAuthors K. Tertyshnikov, R. Isaenkov, P. Shashkin, O. Collet and R. PevznerSummaryWe present a field experiment using a high-frequency sparker source and a fibre optic cable cemented behind a deep well casing as a receiver array. The trial is conducted at the Curtin University GeoLab research facility in Perth, Western Australia. The study provides insights into using such a combination of high-frequency seismic sources and DAS for practical applications.
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Fiber Optics Data Management from Field to Insights
More LessAuthors N. Ma and D. TishechkinSummaryIn O&G industry, DAS and DTS systems generate large volumes of data continuously. The data rates can exceed 10 MB per second, leading to over 1 TB of data per day per well. A DAS installation for near-surface monitoring could produce terabytes of data daily. Handling and storing this massive amount of data at scale can be a challenge, particularly for remote locations where infrastructure is limited. Once the data is acquired, the need for having data quality check, data processing, and data analysis in near real-time pose computational challenges that often requires high-performance computing resources.
In this abstract, we will share a scalable solution that provides a secure, convenient, efficient, and cost-effective way to store, retrieve, share, and analyze both unstructured DAS/DTS data and structured processed data.
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Image processing of jointly acquired 3D DAS-VSP data with an OBN survey in the Middle East
More LessSummaryJoint surface and borehole seismic are a 3D surface-and-borehole seismic exploration method of the simultaneous acquisition of onshore or offshore 3D seismic and VSP (Vertical Seismic Profile) data using the same sources. When acquiring surface 2D or 3D seismic data in the field, simultaneously acquired 2D or 3D data can provide full well high-resolution structural images around the borehole and enhance surface 2D or 3D seismic data processing significantly. This paper describes the imaging processing of the 3D DAS (Distributed Acoustic Sensor) VSP data acquired by a downhole armored optical cable simultaneously with a 3D OBN data acquisition project in the Middle East. Apart from the conventional processing steps of 3D VSP data, the deblending processing of the multi-well blended acquired 3D DAS-VSP data using multiple airgun sources, special ringing noise removal procedure, joint domain full waveform inversion (JDFWI) for velocity model update, and one way wave equation multiple migration (OWEMM) method were used to generate final imaging. The results provide client with good quality imaging in a relatively large subsurface area.
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Development of 3-C Fibre Optic Sensors, a Comparative Analysis with 3-C Geophones and DAS FO Cable
More LessAuthors S. Soulas, G. Tubridy, S. Berry, P. Royds, T. Tubridy, B. Kaack, W. Wills, S. Wellens, S. Bridger, K. Hann and C. BirdSummaryA combined DAS-1C on hybrid wireline with two 3-C optical seismic sensors at the bottom was used to acquire a zero offset VSP survey in the Avalon test site in Cornwall, Rosemanowes Quarry using a seismic vibrator and airgun source. The test site comprises multiple deep deviated wells with 9 5/8” casing, wells drilled in the 80s as part of the UK Hot Dry Rock Geothermal Energy Research program.
The reference downhole antenna is our 3-component geophones array with 4 levels run on wireline from TD to surface and used as benchmark for the analysis.
The Avalon system is an all-optical solution without downhole electronic components. The sensors are discrete 3-component fibre-optic point receiver accelerometers designed for slim hole tools to cope with any sized wellbore and borehole deviations.
The acquired vibrator and airgun datasets enabled many quantitative comparisons between the three sensor types. These comparisons allowed the relative merits of cable-deployed DAS systems and 3-C vector sensors to be evaluated using a defined data analysis workflow. In this paper we describe our findings in terms of SNR, frequency responses, vector fidelity, sensitivity, and comment on the current state of DAS technology and 3-C optical point sensors versus 3-C geophones
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Can Aircraft Noise be Detected with a Buried DAS Array?
More LessAuthors B. Gurevich, K. Tertyshnikov, R. Isaenkov, R. Pevzner and M. VorobevSummaryField experiment using a buried DAS telecommunication cable shows that propeller aircraft are detectable on spectrograms of DAS data by their characteristic Doppler signature. Their parameters and trajectory can be estimated (using multiple DAS channels). The detection range is about 2 to 3 km. Detecting noise form jet aircraft requires a smaller gauge length.
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What Elastic Parameters Control Direct P-wave Amplitude in DAS Measurements?
More LessAuthors B. Gurevich, W. Hou, O. Collet, S. Glubokovskikh and R. PevznerSummaryThe amplitude of a seismic wave measured by a sensor depends on the properties of the medium around the sensor: the softer the medium, the larger the amplitude. For instance, if the sensors are distributed along a borehole, this dependency can be used to characterise the medium around the borehole and to detect changes of the medium properties over time. The specific parameter that controls the seismic amplitude depends on the quantity measured by the sensor as well as the type and direction of wave motion. Continuity of the stress traction implies that distributed acoustic sensor (DAS) amplitude of a low-frequency plane P-wave propagating along the fibre should scale with the inverse of the plane-strain (or P-wave) modulus M=(c∧2 ρ) of the formation (ρ is formation density and c is the P-wave velocity). Conversely, energy-flux conservation implies that DAS amplitude is proportional to (M∧3 ρ∧(-1) )∧(-1/4)=(c∧3 ρ)∧(-1/2). To understand the applicability of these two relationships, we perform theoretical analysis and numerical simulations, which reveals that the DAS amplitude scales with 1/M for thick layers and with 1/√(ρc∧3 ) for thin layers (relative to the wavelength).
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Modelling Depth Dependency of Rayleigh-wave DAS Amplitudes in Multilayered Media
More LessAuthors F. Chen, B. Gurevich, B. Yang, O. Collet, S. Glubokovskikh, K. Tertyshnikov and R. PevznerSummaryDepth variations of Rayleigh-wave amplitude in multilayered media are controlled by a complex combination of exponential decay of different modes as well as stiffness of individual layers. The widespread deployment of downhole fibre-optic cables provides an important opportunity for investigating the depth dependence of Rayleigh wave amplitude using distributed acoustic sensing (DAS). However, quantitative understanding of these dependencies is lacking. Here we model the Rayleigh-wave vertical strain amplitude versus depth for frequencies from 0.03 to 0.2 Hz theoretically and numerically, and compare the theoretical and numerical results to observed DAS amplitudes. Modelling results show that both modelled and observed DAS amplitudes display a clear anomaly at the depth of a CO2 saturated reservoir. The numerical amplitudes for a source depth of 5 km, 600 km away from the well location, have a reasonable agreement with the field data at about 0.1 to 0.2 Hz. However, at lower frequencies the agreement is not attainable, which requires further investigation.
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Crack Detection using DAS for Concrete Structures
More LessAuthors S. Miyanaga, H. Arai, R. Sato, T. Takahashi, T. Tsuiji, M. Yamagami and Y. SanadaSummaryWe propose a crack detection method to simplify the visual crack inspections on large concrete structures such as dams, tunnels, and bridges, which consume enormous amount of time and labor. The method uses Rayleigh waves attenuated by cracks, and it has been implemented in geophones but not in DAS. In this study, to demonstrate the applicability of DAS for crack detections, we measured and analyzed Rayleigh waves using DAS on a concrete slab with cracks. In the measured data, attenuation of Rayleigh waves was observed near cracks, suggesting that the cracks can be detectable. The measured results also show that the frequency of the attenuated Rayleigh waves depends on the depth of the crack. However, the attenuation and recovery of the waves unrelated to the cracks were observed, seemingly because reflected waves generated at the slab edges are mixed with surface waves, thus reducing the data quality. To apply this crack detection method to actual structures, further investigations is required into reflected waves generated at the edges of the structure, as well as the relationship between spatial resolution of interrogators and detectable crack depth.
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Numerical Experiments on Seafloor-deployed DAS with Helical Fibers for CO2 Sequestration Monitoring with Time-lapse Elastic FWI
More LessAuthors S. Masaya, M. Tani, Y. Liu and I. TsvankinSummaryDistributed acoustic sensing (DAS) with optical fiber cables has actual and potential applications, including energy applications, because it can densely measure the vibrations along the optical fiber compared with conventional receivers. For example, we already utilize DAS measurement for subsurface seismic monitoring by installing an optical fiber cable in a borehole. DAS with optical fibers deployed at the seafloor has also the potential for CO2 sequestration monitoring. However, seafloor or surface-deployed DAS for seismic acquisition still has a technical challenge for the directional sensitivity of fibers. DAS with a straight fiber cable does not effectively detect the vertical component of seismic waves, such as reflected P-waves. A method to address this challenge is helically wound fiber (HWF), which theoretically measures the summation of the vertical and horizontal components of vibration. However, there is no report on deploying HWFs for DAS measurement at the seafloor. Therefore, this study investigates the validity of seafloor-deployed DAS with HWFs for CO2 sequestration monitoring using time-lapse elastic full waveform inversion (FWI) for 4D seismic data. We show numerical examples to evaluate the relation between the accuracy of the time-lapse change estimated by FWI and wrapping angles of HWFs in seafloor-deployed DAS.
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Long-range Distributed Acoustic Sensing – Key Learnings from Laboratory Experiments
More LessAuthors O. Collet, E. Sidenko, B. Gurevich and R. PevznerSummaryIn recent years, long-range Distributed Acoustic Sensing (DAS) has raised significant interest notably due to the improvement in long-range sensing capabilities and the ability to use tens or hundreds of kilometres-long telecommunication cables as dense arrays of acoustic sensors. In this study, we describe laboratory experiments that have been designed to investigate long-range DAS capabilities. In particular, we analyze the sensitivity of the noise floor and the detectability of various signals at different locations along the fibre-optic cable for cable lengths varying from 10 to 200 km. These results can provide guidance on the DAS acquisition parameters to use for specific applications and cable setups.
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Microseismic Event Location with Joint DAS and 3C Geophone Array
More LessSummaryFiber-optic distributed acoustic sensing (DAS) applied to microseismic has gained popularity in various microseismic monitoring applications. Compared to conventional geophone array based microseismic monitoring, DAS microseimsic has unique advantages in minimizing location uncertainties. However, if only one straight fiber were deployed on surface or in downhole, DAS may not be able to uniquely determine a microseismic event location without other constraints due to circular event location ambiguities. Since a standard DAS fiber cable usually can only record one component seismic wave data which is not able to provide source direction to reduce the circular ambiguities in event location, we developed a innovative joint DAS and 3C geophone array for microseismic monitoring and a three-step microseismic event location workflow to obtain a unique event location. First, we calculate source direction using P-wave first arrival on 3C geophone. Second, we calculate 2D semblance image along the source-geophone direction. Third, we extract the location of maximum semblance value in 2D semblance image as the event location. We presented a microseismic event location example which was obtained by applying the three-step location workflow on microseismic event dataset acquired by a field survey with joint DAS and 3C geophone array.
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Disposable Fibre Optic System: Two Hot Land Well Surveys Inform Plug and Abandonment Plan
More LessAuthors R. Crawford, A. Green and P. KokkoniSummaryA disposable fibre optic deployment system was selected to conduct DAS and DTS leak detection data to inform a plug an abandonment campaign. The system consists of a downhole probe which deploys bare fibre as it is gravity deployed in the wellbore, with minimal surface hardware it was deployed to a remote location in a single passenger vehicle. Bare fibre was deployed in 2 remote land wells with temperatures of up to 200°C and sustained casing pressure was sequentially bled off to activate leak paths to surface. The survey identified 6 discrete integrity concerns indicating that reservoir pressure was connected to surface with no casing leaks identified. As a result, the abandonment plan was designed to focus on deep barrier restoration at the cap rock. The case study demonstrates the utility of DAS and DTS surveys for land well abandonment activities, using a disposable bare fibre optic system to reduce mobilisation footprint and cost.
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Feasibility of P-S Converted Wave Imaging for the DAS Active Seismic with Surface Deployed Optical Fibers
More LessAuthors R. Naruse and Y. KobayashiSummaryDistributed Acoustic Sensing (DAS) is an important technology for a long-term monitoring for geological carbon storage as optical fiber cables are durable for years. Theoretically, DAS measurement using optical fibers deployed on surface (S-DAS) record P-P reflected and P-S converted wave simultaneously in an active seismic survey. This study explores the possibility of the P-S converted wave imaging with S-DAS 2D land seismic data from a field trial conducted in Japan.
We performed preliminary P-P reflection processing and P-S converted reflection processing on the same data set. Reflection events that is not clear in the P-P reflection image are observed clearly in the P-S converted reflection image in the shallow area. This may be attributed to the difference in impedance contrasts and sensitivity of DAS for a wave incident angle to cable. Imaging of deep area might be challenging in terms of the degree of S wave attenuation.
We confirm that S-DAS measurement can give subsurface image both by P-P reflection and P-S converted wave, and that P-S converted wave gives additional information to leakage monitoring for shallow zone in the geological carbon storage.
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