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EAGE GeoTech 2024 Fourth EAGE Workshop on Distributed Fibre Optic Sensing
- Conference date: April 8-10, 2024
- Location: The Hague, Netherlands
- Published: 08 April 2024
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Deep Learning in Reservoir Characterization: a GAN-based Approach
Authors A.A.A. Al-Fakih, S. Kaka and A. KoeshidayatullahSummaryThis extended abstract introduces a pioneering approach to reservoir characterization in the oil and gas industry, utilizing Generative Adversarial Networks (GANs) to create multi-dimensional geological models. The method encompasses meticulous data collection, preprocessing, and the application of Deep Convolutional GANs to generate synthetic reservoir models. These models are rigorously evaluated, offering valuable insights into subsurface properties and structures. Integration with other data sources enriches the understanding of reservoir behavior. The results suggest that GANs hold significant potential in enhancing accuracy and efficiency in subsurface modeling, with applications extending beyond the energy sector. This approach promises to reduce uncertainties in reservoir characterization, optimize production, and contribute to safer and more sustainable operations in the industry. The study acknowledges the support of various institutions and researchers, underlining the collaborative effort behind this transformative research.
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A VSP Turkey Shoot Trial on Hybrid Cable Comparing FO DAS, 3-C Geophones and FO Sensors
Authors S. Soulas, G. Tubridy, S. Berry, P. Royds, T. Tubridy, B. Kaack, W. Wills, S. Wellens, S. Bridger and J. RawlingsSummaryA combined DAS-1C on hybrid wireline with 4 traditional 3-C geophone sensors at the bottom was used to acquire a zero offset VSP survey at the Avalon test site facility in Cornwall, Rosemanowes quarry using a seismic vibrator. This was compared with a wireline run from our early prototype development of our Avalon 3-C optical system in the same well for benchmarking. Our test site comprises multiple deep deviated wells with 9 5/8” casing, wells drilled in the 70s as part of the UK Hot Dry Rock Geothermal Energy Research program. Multiple DAS partners were invited to participate to the DAS turkey shoot and record independently the DAS data part alongside with ASL recording the 3-C data simultaneously with exact same recording downhole conditions.
The acquired active data 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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DAS-VSP for 4D Reservoir Monitoring and Overburden Imaging
Authors K. Liao, B. Cooper-Barnard, H. Moore, M. Farshad, H. Westerdahl, Y. Biryaltseva and P.A. OlsenSummaryThe CCS industry demands a reliable and cost-effective solution for monitoring the integrity of injected CO2 containment, to accelerate the process of reducing greenhouse gas emissions. Acquiring low-cost seismic data using DAS, coupled with the availability of advanced imaging algorithms, has attracted significant attention in recent years. In this paper, we present distinct and convincing 4D signals recorded in field DAS-VSP seismic data. Crucially, these 4D signals are validated by OBN seismic data acquired simultaneously by the existing Permanent Reservoir Monitoring system. This validation confirms the efficacy of DAS-VSP data for 4D seismic monitoring.
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2D Water Basin Tomography Using the Combination of DAS Acquisition and Seismic Interferometry
Authors D. Nziengui Bâ, C. Jestin, O. Coutant and V. LanticqSummaryDistributed Acoustic Sensing (DAS) is an emerging solution for underground exploration and monitoring. We study here the potential of the combination of DAS with seismic interferometry for shallow structures imaging. We base our work on records achieved in the Crépieux-Charmy wellfield, managing the water supply of the city of Lyon, France. Four weeks of urban seismic noise have been acquired during water infiltration operations, using DAS system along a 200m linear fiber optic cable deployed at the bottom of an infiltration basin.
Using ambient noise interferometry principles, we obtain a 2D profile of depth-dependent shear wave velocity variations δβ/β(z), enabling the monitoring of the water level in a shallow aquifer. A good correlation between these results with piezometric measurements is observed. This work then highlights the promising potential of this method for the continuous and precise monitoring of underground structures involving changes in medium velocities.
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Stratigraphy and Structural Prediction through Advanced Machine Learning: Case Studies for Hydrocarbon Exploration and Carbon Storage
Authors C.T. Ang and A. ElsheikhSummarySeismic stratigraphy mapping, a crucial technique in subsurface exploration, is enhanced by the integration of machine learning methodologies to identify and assess potential reservoirs for both hydrocarbon exploration and carbon capture, utilization and storage (CCUS) applications. This study explores the integration between traditional seismic stratigraphy mapping and machine learning algorithms, demonstrating its efficiency in mapping and derisking the subsurface structures, and optimizing decision-making processes whether for reservoir exploration, development or management.
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2-Phase Water-Oil Flow Profiling from DAS Using Simple Assumptions
More LessSummaryIs it possible to obtain a 2-phase (Water+Oil) flow profile from DAS using simple assumptions? Ge Jin et al (urtec-2019-943) have presented a complete workflow to obtain cluster level flow allocation results in unconventional wells producing two phase water and oil at downhole conditions. We explore alternative methods of finding the flow velocity and whether simple assumptions can be used to directly convert the velocities into water and oil rates at the measured points.
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Meeting the Challenges of Downhole Sensing through the Application of True Fibre Optic Point Sensors
More LessSummaryBrett Bunn and Paul E. Murray share the significance and utility of a newly developed multicomponent all-optical downhole sensor system that provides true point sensing of the elastic wavefield. Not only does it offer high vector fidelity, low noise, time-stationary response characteristics, and tremendous dynamic range, but it does this in high temperature, high pressure environments, with years-long lifetime.
These optical accelerometers use a laser interrogator to convert motion to optical interference phase with ultra-high dynamic range and high linearity. All components of the fiber optic sensors and telemetry are passive, with no electronics downhole, delivering long life and very high reliability at temperatures greater than 150 °C. Arrays are configurable from one to hundreds of receiver levels at custom spacings. The interrogator may be located any distance from the borehole up to tens of kilometers away.
These characteristics make the tool particularly useful for both active and passive (microseismic) surveys for CCUS applications. The time-stationary response characteristics are necessary for deriving time-lapse (4D) characterization of a reservoir and surrounding geology.
Analysis and discussion of VSP and near-offset field test data exploring the tool’s capabilities is also provided.
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Interpretation of Low-Frequency DAS Data Acquired during Hydraulic Fracturing Treatments Based on Geomechanical Models
Authors A. Ortega Perez and M. Van der BaanSummaryLow-frequency strain waterfall plots with their corresponding pumping curves were analyzed to obtain information on fracture azimuth, propagation speed, number of fractures created in each stage, and re-stimulation of pre-existing fractures. We also use a simple geomechanical model to predict fracture growth rates while accounting for changes in treatment parameters. Most fractures propagate in the direction of maximum horizontal stress. Multiple frac hits are visible, thus multiple parallel fractures are created and/or re-opened. Secondary fractures deviate towards the heel of the well, likely due to the cumulative stress shadow from previous stages. The presence of heart-shaped tips reveals that some stress and/or material barrier is overcome by the fracture. The lobes of the heart are best explained by the shear stresses at 45-degree angles from the fracture tip instead of the tensile stresses directly ahead of the tip. Antennas ahead of the fracture hits indicate the re-opening of pre-existing fractures. Tails in the waterfall plots provide information on the continued opening, closing, and interaction of the hydraulic fractures within the fracture domain and stage domain corridors. Analysis of the low-frequency DAS plots thus provides in-depth insights into the rock deformation and rock-fluid interaction processes occurring close to the observation well.
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3D Modelling of Standard Penetration Test in the Framework of Assessing Liquefaction Risk
Authors P. Masoudi, H. Binet, C. Simon, B. Pelletier, C. Faucheux, F. Rambert and Y. AssySummaryThis article presents an application of geostatistics at the geotechnical study phases, prior to construction on a nuclear site. The site under investigation is on dense tertiary sands where the shallow depth layers may include some loose lenses from the point of view of geotechnics. Therefore, it is decided to estimate the potentially liquefiable soil volumes to remove and substitute before constructing the nuclear power plant. The liquefaction is studied by combining several geotechnical parameters. One of such parameters is the Standard Penetration Test (SPT). In this study, a 3D block model of SPT is constructed using ordinary kriging method of interpolation, and the probability of SPT exceeding a threshold of 15 counts (simplified no-liquefaction criterion) is evaluated using Turning Bands Simulation (TBS). Accepting the risk of 30%, the results are mapped and visualized for the elevation of −10 m AOD, which is the base of the general excavation.
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Calibrated DAS Moment Magnitudes: Moving from Strain to Ground Motion Using Downhole Microseismic Monitoring Data
Authors B. Boullenger, A. Butcher, B. Paap, V. Vandeweijer and A. StorkSummaryDistributed acoustic sensing (DAS) provides axial strain measurements along optical fibers whereas ground motion quantities can be required for interpretation or inversion processes. Using co-located DAS and reference accelerometer records from the downhole monitoring setup of the FORGE (Frontier Observatory for Research on Geothermal Energy) site, we apply a DAS transfer function workflow to obtain calibrated velocity records of microseismic events from initial DAS (strain rate) measurements. The calibration workflow is based on the conversion of physical units using frequency-wavenumber domain transformations and on the correction of the remaining misfit to the reference. This misfit, which corresponds to a factor of approximately two for the P-wave arrivals, is quantified in terms of a frequency response in the range 50–200 Hz. We analyze such DAS system responses as a function of the co-located depth positions and we show that, after corrections, we can determine the moment magnitude (Mw) reliably from DAS for microseismic events with Mw > −0.9.
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A Step Forward in DAS VSP Acquisition in Vertical Exploration Wells: a North Sea Case Study
Authors R. Guerra and P. MacLeodSummaryIn 2023, Dana Petroleum drilled a vertical exploration well in the UK North Sea to a total depth of more than 10,000 ft [3,048 m] TVD. A vertical seismic profile (VSP) was required to accurately measure the interval velocities and the reflectivity response of the rocks around the wellbore and to support a robust well-seismic tie.
Conventional VSP surveys use geophone arrays and can take more than 12 hours to complete. In this case study, the operator opted for a faster alternative using an ultra-strength hybrid optical-electrical logging conveyance system that also ensures safe operation in difficult wells. The fiber-optic technology allows distributed acoustic sensing (DAS) data to be recorded during any wireline logging run.
The DAS low frequency strain along the cable was monitored after each cable slack test, allowing optimal cable coupling to be achieved with a slack of 200 ft [61 m]. A rig source airgun array fired 30 shots and the stacked DAS data showed good quality and a bandwidth of 5–80 Hz at target. Real-time monitoring helped the operator decide to cancel the backup geophone run. The technology saved 8 hours of rig time, which translated into lower costs and reduced environmental impact.
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Distributed Fibre Optic Sensing for Geothermal Applications
SummaryGeothermal energy projects vary significantly in the temperature and target depths of the thermal energy source. The industry seeks for cost-effective, continuous monitoring solutions to maximise operational efficiency and safety. Distributed fibre optic sensing (DFOS) solutions provide flexible, multi-parameter measurements for the exploration and exploitation of the full range of geothermal resources, from shallow borehole, ground source heat to hydrothermal geothermal projects and Enhanced Geothermal Systems (EGS). Permanently installed integrated fibre optic sensing-based solution offers reliable, long-term geothermal reservoir monitoring and helps operators comply with legal requirements. The sensing element, a single fibre optic cable, either installed in shallow heat exchanger wells or cemented behind casing to the reservoir depth, can provide simultaneous and continuous measurements including temperature, seismic, microseismic, flow distribution, and strain. Here we present an overview of case studies of DFOS monitoring for a range of geothermal applications.
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Temperature Logging in Selected Geological Boreholes: DTS vs. Manual Profiling. Preliminary Results of the OptiSGE Project
SummaryThe Polish Geological Institute - National Research Institute (PGI-NRI) and NORCE Norwegian Research Centre (NORCE) under the terms of the bilateral project “Optimization of Shallow Geothermal Energy Resources for Green Transition (OptiSGE)” are carrying out logging of subsurface temperature in the selected boreholes in SW Poland. The project aims to strengthen the green transition by implementing innovative methods for the assessment and use of low-temperature geothermal energy resources to support the economy and societies in Poland and Norway as well as to contribute to decarbonization of the energy sector. In addition, results of field measurements including temperature logging supply reference data for the development of the low-temperature geothermal potential maps completed by the PGI-NRI.
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