85th EAGE Annual Conference & Exhibition - Workshop Programme
- Conference date: June 10-13, 2024
- Location: Oslo, Norway
- Published: 10 June 2024
1 - 20 of 64 results
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Fault Zone Structure and Fluid Flow Behaviour in Shale-Rich Sequences
More LessAuthors C. WibberleySummaryThis presentation reviews some challenges and recent progress in predicting fault properties and fluid-flow behaviour in shale-rich sequences. Fluid flow behaviour of fault zones is controlled by their structure, including potentially core and damage zones. Building on an understanding of the factors controlling such fault zone internal structure, achieved from outcrop studies, prediction of these structures and influence on subsurface flow relies on knowledge of composition and geological history of topseals which together impact mechanical behaviour at the time of faulting.
Quantification of fault permeability and hydraulic behaviour comes partly from laboratory measurements of samples from analogue fault zones, pressure measurements in wells around faults, and in-situ well tests dedicated to measuring fault behaviour.
A challenge of societal importance is understanding hydro-mechanical behaviour of faults when subjected to anthropogenic stress or pore pressure, with respect to reactivation, seismicity, and leakage. Current work is presented on predicting, from geological history, the generation of dilatant and / or compactant structures susceptible to enhance the conduit or sealing behaviour of a fault zone, and pressure data from wells around active faults used to better understand fluid retention and fault shear limits, concluding with perspectives to further our understanding of fault hydro-mechanical behaviour.
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QC of a Marine Vibrator
More LessAuthors T. Elboth, T.A. Nilsen, A. Nilsen and J.P. Merlin ErtelSummaryWe present the concept and functionality of a recently deployed marine vibrator Quality Control (QC) system. This system, recently utilized for the first time, facilitates both real-time and long-term monitoring of each subsystem within the vibrators. It plays a dual role in overseeing geophysical signal quality and ensuring equipment reliability, contributing to the overall enhancement of the vibrator system.
The QC system is equipped with over 30 sensors on each vibrator and continuous monitoring in a 24/7 operational setting becomes a challenging task for human operators. To address this challenge, a multi-level QC system that relies on computed attributes has been developed. It notifies the user through visual color-coding and audio alarms, enabling efficient detection of potential issues. In case of a flagged problem, the system supports a detailed investigation.
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The Physics of CO2 being a Greenhouse Gas
More LessAuthors L. Amundsen and M. LandrøSummaryWe review the physics of CO2 being a greenhouse gas in terms of well-known concepts: blackbody radiation which tells that Earth’s radiation because of the Sun’s heating lies in the infrared portion of the electromagnetic spectrum, the CO2 absorption spectrum which indicates the ability of CO2 molecules to absorb infrared photons sent out from Earth’s surface at particular frequencies (or wavenumbers), and the the photon’s mean free path which is the average distance over which a moving photon travels before being absorbed by the CO2 molecule. The size of the mean free path is strongly frequency (or wavenumber) dependent and inversely proportional to the CO2 concentration. This observation is the key to appreciate that an increase in CO2 concentration in the atmosphere has the effect of increasing Earth’s temperature because more photons (radiation) radiated by Earth have the likelihood of returning to the Earth’s surface, thereby heating it.
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Over 30 Years of Migration Velocity Analysis based on Differential Semblance Optimization
More LessAuthors H. Chauris and M. FarshadSummaryMigration Velocity Analysis is a technique to determine the large-scale velocity structure of the subsurface from the analysis of reflected data. We review here the Differential Semblance Optimization version (DSO-MVA) that estimates the focusing in extended panels. Theoretical arguments ensure a convergence to the global optimal with a local optimization process. In practice, it faces a number of challenges: reflected events should be first extracted from the observed data; the computational cost is currently expensive due to the number of wavefields; a proper amplitude processing is needed before the evaluation of the focusing. The recently developed approximate inverses for replacing the standard adjoint images have played a significant role. In its current shape, DSO-MVA ensures focused images as well as a (linear) data fit at convergence. Recent researches consider a fully non-linear imaging tool, while preserving the DSO-MVA convergence properties.
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Designing a Deep-Sea Mining System for Seafloor Massive Sulphides in the Norwegian Jurisdiction
More LessAuthors M. LesageSummaryThe global efforts to develop a greener society through renewable energy development leads to a consequential demand for metals. As the adequacy of future metal supply is debated, marine minerals offer an alternative source yet to be commercially exploited. Norway’s decision to open its jurisdiction for the commercial exploration of marine minerals marks a significant step towards deep-sea mining. Green Minerals, anticipating this decision, collaborates with partners for a conceptual study on a Harsh Environment Deep-Sea Mining system. The study considering local parameters, addresses the technical feasibility of Ship-To-Ship (STS) operations. Methodologically, a general function structure guides the conceptual study, focusing on subsystems such as a subsea mining machine, slurry transportation, and offshore ore offloading. The chosen subsea mining machine, a marinized excavator by SMD, extracts minerals from the seabed as a slurry. A riser pipe system and a subsea pump vertically transport the slurry from the seabed to the surface. Oil & Gas STS fluid transfer methods are examined, presenting shooting lines and a disconnectable turret as potential solutions, with the latter enabling weather-robust transfer and facilitating personnel transfer.
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The Energy Transition, Societal Issues and how Geoscience can Contribute
More LessAuthors P. RingroseSummaryThe energy transition presents a major challenge for our society. The main tools for enabling rapid reductions in greenhouse gas emissions are well known, but implementing these vectors of decarbonisation will be challenging, partly for economic reasons and partly due to social resistance. Geoscientists working to support the energy transition have two overall tasks: they need to engage technically to enable low-carbon emissions projects to proceed, but they also need to engage with society to communicate and explain the risks and benefits of projects in a more effective way.
Geoscientists have many of the critical skills needed to support the energy transition, so the future of applied geoscience should be bright. However, challenges with financing of clean energy projects and growing social opposition to new projects means that the road ahead will be challenging.
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Industry Application of Fault Seal Prediction Methods. Experience from Petrophysical Data and Fault Process Understanding
More LessAuthors S. OttesenSummaryFault seal modelling workflows have been used unchanged for a long time for determining number of wells and well placements in field development or predicting remaining reserves in late life field production. We are however still struggling with trusting the predictions, and lately the old methods are being questioned and new methods have been suggested. In this presentation experiences from >25 years of fault seal work will be presented and try to demonstrate why simple solutions trying to calibrate against single parameters for calibration (like depth or SGR) is not logical. There is a general depth trend where shallow reservoirs have the smallest reduction in permeability when faulted. However, there is about 2 orders of magnitude variation of reduction of fault permeability vs undeformed reservoir rock permeability for reservoirs at similar depths. What can we learn from practical use of manually defined SGR/Fault permeability relationships which are based on core measurements, and how does it link to fault deformation processes, depth and rock composition?
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Fault Permeability in Porous Sandstone Reservoirs: a Short Review of Controlling Factors
More LessAuthors F. Balsamo, M. Pizzati, C.F. Nogueira, F.H. Bezerra, F. Storti and J.A. SouzaSummaryIn poorly lithified and porous sandstone reservoirs, the typical fault zone structure consists of a narrow fault core (made of foliated cataclasites and gouges) surrounded by a damage zone (containing tabular deformation bands). Both fault core and damage zone are generally low permeable domains, but with permeability values that varies over a large range from 10-6 to 10 Darcy. Depending on their internal architecture (e.g., fault core and damage zone widths, density of deformation bands) and related petrophysical properties, faults in porous sandstones can either act as retarders, effective seals or even conduit-barrier for fluid flow. Several geometric, environmental and lithological factors control the structure, petrophysical properties and, consequently, the hydraulic behaviour of faults developed in porous rocks. The aims of this contribution are (i) review the published papers on faulted poorly lithified sandstones to extract fault permeability data, (ii) integrate published dataset with unpublished material to increase the number of case studies, and (iii) compare the datasets to understand the fault permeability evolution in different types of sandstones. The ultimate target of this contribution is to stimulate the discussion on the main factors (particularly fault displacement, burial depth and host rock mineralogy) controlling the evolution of fault zone permeability.
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Cascaded Least-Squares Multiple Imaging for Reduced Multiple Crosstalk
More LessAuthors G. Poole and M. FarshadSummaryMany modern towed-streamer and ocean-bottom node acquisition geometries designed for deep targets do not capture small reflection angles from shallow events. This results in shallow images that are degraded by significant wavelet stretch and acquisition striping. Multiple imaging has been established as one way to address this issue; however, results may be contaminated with multiple crosstalk in many cases. We propose a cascaded least-squares multiple imaging approach to overcome causal multiple crosstalk, successively imaging to increasing depths. Data domain residuals based on each image are used as input to the subsequent multiple migration step to prevent multiple crosstalk forming in the deeper section. The approach has proven to be robust, with its effectiveness being demonstrated on three field data examples.
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Ultra-Resolution Nodal Seismic and Machine Learning for Geohazard Analysis
More LessAuthors D. Colombo, E. Sandoval-Curiel, T. Alyousuf, E. Turkoglu and D. RovettaSummaryShallow geohazards are found in areas where near surface formations such as carbonates or evaporites are subject to dissolution related to the circulation of water. We develop a workflow for rapid and detailed screening of the shallow subsurface in search of potential geohazards. Seismic acquisition is performed with dense nodal arrays providing a detailed spatial sampling of the wavefield. Automated data analysis involves transmission surface-consistent decomposition and corrections, followed by beam forming with virtual super gathers. Machine learning is utilized for different tasks of processing and inversion of multi-wave data. A collection of surface-consistent attributes and geophysical parameter distributions with depth is generated. The ultra-resolution seismic and the automated data analysis is successfully applied for the evaluation of geohazards at several drilling locations.
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The Iris License CCS Project – Fast Track to Success
More LessAuthors C. Dybbroe Tang, T. Roth and A. SzabadosSummaryAfter successful tests of monitoring technologies in the Greensand pilot project, a smart and lean monitoring concept was setup for the fast track storage project in the Danish Iris license, the Nini site. This concept allows targeted monitoring honoring the specific challenges for injection of CO₂ into a depleted oil reservoir. The talk will cover the methodology for developing an MMV plan as well as the concept of annual updates in a Predictive Maintenance Plan (PMP).
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Sinkhole and Cavity Detection through Satellite Radar Data: Exploring Potentialities and Addressing Challenges
More LessAuthors A. Ferretti, S. Cespa and S. PresezziSummaryThis paper explores the application of Interferometric Synthetic Aperture Radar (InSAR) in detecting and monitoring sinkholes and cavities, focusing on its potentialities and challenges. InSAR’s ability to detect surface deformation phenomena, including subtle changes induced by sinkholes and cavities, has been demonstrated in various applications. Despite its advantages, challenges such as spatial resolution limitations and temporal sampling constraints persist, hindering precise sinkhole identification. However, the paper anticipates significant advancements with the upcoming launch of SAR constellations featuring high spatial resolution and short repeat cycles. Integration of InSAR into mainstream monitoring practices is advocated to enhance resilience and mitigate risks.
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Remote Detection of Karst – from Remote Sensing to Seismic
More LessAuthors A. LaakeSummaryKarst is a dissolution phenomenon that occurs in carbonate, sulphate, and salt rocks. Recently, thawing and dissolution of permafrost soil has been included in the group of karst processes as thermokarst. The karsting process generates cavities in the subsurface that are widened to caves by water-based processes. Ultimately, the collapse of the cave roof creates openings to the surface. Karst cavities represent a multiplicity of hazards to infrastructure and engineering activities, highlighting the importance of the remote detection of karst.
Proven methods for detecting karst features target heterogeneities in the subsurface and their impact on the surface. Radar satellite remote sensing can be employed to detect sinkholes and other collapse features, whereas multispectral satellite imagery provides information about vegetation anomalies associated with changes in the subsurface. Once karsting has been detected from remote sensing, then ground-based methods like shear wave seismic surveys or ground penetrating radar are employed to map karst features in 3D. Case studies for different types of karst illustrate how remote sensing methods allow the mapping of karst features onshore and offshore.
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Characterisation and Monitoring of Injected CO2 Using Multiphysics Approaches: an Example from a Carbonate Reservoir
More LessAuthors L. MacGregor, N. Ralim, J. Kho and T. JayasangarSummaryWe discuss the pros and cons of a multiphysics approach to the monitoring of injected CO2, and where non-seismic data can complement and augment seismic approaches for this purpose. We illustrate this with a combined electric/elastic sensitivity analysis for monitoring of a CCS site in Malaysia in which both seismic and CSEM data, and their combination, are considered.
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Application of Digital Core Analysis to Carbon Storage: Luna Project Case Study
More LessAuthors A. Fogden, T. Bollermann, E. Huebner and S. AlakbarovSummaryThe Luna storage site is located in the northern North Sea, close to the Brage platform, the Northern Lights Aurora and the Smeaheia licences. The Statfjord Gp is selected as primary reservoir for the Luna CO2 sink. To fulfil the requirements for storage site certification, a comprehensive suite of laboratory analyses and modelling of reservoir and cap-rock core materials, and their interactions with CO2 and brine, have been performed or planned. As data from CO2-brine core-flooding experiments were not yet available, an alternative approach based on digital core analysis was applied to generate fast-track input of dynamic properties to reservoir modelling. In this Luna project case study, limited remaining core material and simple lab measurements sufficed to represent historical properties and provide anchoring and verification points for the simulated flow property curves.
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Characterization of Subseismic Fault Zone Heterogeneity for Fault Seal Analyses
More LessAuthors J. Solum, S. Jolley, N. Duffin and K. OnyeagoroSummaryFault seal analyses address the potential for fluids to accumulate on one side of a fault zone (static fault seal); and/or the rate at which cross-fault flow is expected to occur (dynamic fault seal). Neither static nor dynamic fault seal can be uniquely predicted since they are both strongly influenced by cm-m scale lateral variabilities in reservoir and fault zone architectures, diagenetic effects, and fluid properties. The smear/core integrity, mineralogy and permeability characteristics are critical to fault seal prediction – but these features are too small to directly measure, or predict, from the types of data that are routinely used to make subsurface models (e.g., 3D reflection seismic). Thus, faults that are similar on seismic data can have very different subseismic fault zone architectures and therefore very different static and dynamic fault seal characteristics. Fault seal studies, especially in data-sparse situations, therefore, aim to predict a range of geologically realistic values instead of a single value of fault seal capacity.
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From Generic Monitoring-Concepts to a Risk-Based and Site-Specific MMV-Strategy for the Porthos CCS-Project
More LessAuthors G. Thuerschmid, L. De Groot, H. De Haan and M. BoutsSummaryCCS-projects are in a relatively early stage when operators are applying for a storage license. A plan for measurement, monitoring and verification (“MMV”) of the CO2-storage is an essential and obligatory part of the license application documents. This initial plan provides the framework of the future MMV-strategy but requires more detailed refinement and eventually also technical updates to ensure that site-specific and operational conditions are properly accounted for, in both a technically best and cost-effective way. In the rapidly emerging CCS-sector, an assessment of potential new, advanced technological developments is therefore also strongly recommended. The presentation will give an overview on the development of a risk-based and site-specific MMV-strategy for the Porthos CCS-project in The Netherlands.
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Fault Damage Zone in Seismic Data
More LessAuthors C. BotterSummaryFault play a key role on fluid flow in the subsurface. They are 3D damage zone with most of the deformation at the centre and decreasing toward the boundary of their damage zone. Seismic data is one of the main ways to characterise them. Here we are going to show the potential of seismic data for characterising fault damage zone. For that we use a multi-attribute analysis that combines dip, tensor and semblance attributes into a combined cube, and additional attributes, such as fault enhancement or total horizontal derivative. These allow us to extract a fault geobody or seismic facies that can relate different deformation intensity within the damage zone. We present examples from synthetic seismic generated for normal faults in siliclastic sequences and on real seismic data where we associate the fault damage through a conceptual model. Such analyses can be used to qualitatively describe fault damage or to condition geomodels of faults in the subsurface.
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Data Domain and Joint Domain Compressive Sensing
More LessSummaryThe objective of seismic processing is to extract the highest resolution subsurface attributes from data acquired in a cost-effective manner. With this goal in mind, Compressive Sensing (CS) theory has become increasingly attractive to geophysicists. Traditionally, CS applications in seismic processing have been concentrated on data domain tasks such as reconstruction and deblending, usually employing optimized non-uniform data sampling and sparse inversion techniques. This paper aims to broaden the application of CS in seismic processing. After a concise review of CS theory, we clarify that CS does not inherently require non-uniform sampling. Moreover, we propose the concept of Joint Domain Compressive Sensing (JDCS), integrating both least-squares migration and full waveform imaging, to leverage CS more effectively. We illustrate how JDCS can markedly improve seismic imaging quality, making efficient use of cost-effective acquisition methods.
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Complex slip Dynamics of a Fault Zone: Decoding and Interpreting Seismic Observation Using Numerical Model
More LessAuthors N. Kheirdast, M. Almakari, C.D. Villafuerte, H.S. Bhat and M.Y. ThomasSummaryIn this study, we explain how mechanical interaction among rate-weakening faults and the damage zone reproduces seismic activity similar to natural observed earthquake catalogues. This similarity is presented in terms of the frequency of magnitudes, the increase in seismicity rate prior to the total breakdown of the main fault, and its decrease thereafter. Exploring the slip rates reveals a broad range of modes of rupture, from slow slip, which hardly radiates energy and can only be observed through geodetic data, to very-low-frequency (VLFE) and low-frequency (LFE) earthquakes that have seismic signatures. We examine the signals produced by these fault movements to observe how a given fault volume radiates waves during a slow-slip event. Additionally, we delve into the fracture energy of the earthquakes, viewing it as a ubiquitous mechanical quantity that explains the coexistence of slow and fast events on the same fault, and how the energy budget determines the rates at which faults break.
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