Seventh International Conference on Fault and Top Seals
- Conference date: September 14-18, 2025
- Location: Bucharest, Romania
- Published: 14 September 2025
1 - 20 of 34 results
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Quantitative Lateral Seal Capacity for Carbon Capture Storage Evaluation: The Case from the Gulf of Thailand
More LessAuthors K. Kreeprasertkul and S. ChantraprasertSummarySedimentary basins in the Gulf of Thailand initially opened in the Oligocene by continental rifting. Syn-rift lacustrine basin fill contains primary source rocks that charged hydrocarbons to the Miocene fluvio-deltaic post-rift reservoirs. Starting in the Pliocene, the depositional environment progressed to shallow marine, providing a shale-rich interval that acted as regional top seals. The petroleum system was completed by the peak hydrocarbon migration in the Pliocene.
This study illustrates fault seal capacity in two perspectives: hydrocarbon exploration and production and CCS. It is observed that fluvio-deltaic depositional environment can contain considerable shale proportion providing a low threshold SGR (0.2) required for hydrocarbon trapping. The seal failure envelope can be used for initial estimation of CO2 storage volumes in CCS project evaluation. The pressure vs depth profile shows that fault seal capacity in the study area has a linear relationship with that of intact top seal strata, which can be useful in exploration and new development projects. This study demonstrates the application in CCS of hydrocarbon fault seal calibration based on well data.
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Caprock Integrity Assessment Thorough a New Multidisciplinary and Multi-Scale Approach
More LessAuthors L. Spaggiari, G.M. Cella, L. Bianchin, A. Corrao, R. Lotti and C. RizzettoSummaryA dedicated workflow, consisting of an integration of multidisciplinary and multi-scale approaches, has been developed and tested within Eni for caprock integrity assessment, by combining commercial software and AI-based solutions with proprietary tools and plugins, specifically devised for this goal.
This workflow provides geological and geophysical integrated deliverables, highlighting the correlations between faults distribution and areas more prone to possible gas escapes through the caprock, to be used as additional input for top seal evaluation, mitigating the risk associated to hydrocarbon exploration and storage activities.
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Assessing Paleo-Seal Integrity in the Greater Bay du Nord Area, Flemish Pass Basin
More LessSummaryThe Flemish Pass Basin, a NE-SW oriented basin over 10,000 km2, contains sedimentary strata up to 10 km thick from the Mesozoic and Cenozoic eras. It is a rift arm of the North Atlantic rift system, with tectonic evolution marked by multiple rifting phases beginning in Triassic to Early Jurassic. Exploration for hydrocarbon accumulations in the Greater Bay du Nord area targets segmented, rotated fault blocks, with studies indicating synchronous hydrocarbon charge with tectonic events.
A study was conducted to reconstruct the 3D shape of the top reservoir layer and assess the seal capacity of Cretaceous top seal units during peak hydrocarbon expulsion. The reconstruction methodology involved seismic horizon interpretation, paleo-water depth mapping, and restoration workflows. The study found good agreement with Tertiary horizons but noted the need for thermal subsidence consideration for Lower Cretaceous horizons. Paleo-seal capacity assessment included identifying seal-bypass systems, analysing pore throat sizes, and calculating hydrocarbon column heights.
The study suggests that the timing of hydrocarbon charge relative to the paleo-seal capacity of Cretaceous rocks might explain underfilled structures in the Greater Bay du Nord Area. It was extended to include Tithonian seals, incorporating geomechanical analyses to evaluate fracture risk and enhance seal integrity assessments.
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Hydrocarbon Migration Dynamics and Seal Integrity in the Flemish Pass Basin: Insights from Migration Modelling
More LessAuthors A. Bernal, J. Zweigel, A.S. Andersen and M.C. DassinniesSummaryThe Flemish Pass Basin, spanning over 10,000 km2, features sedimentary layers up to 10 km thick from the Mesozoic and Cenozoic eras. As part of the North Atlantic rift system, its tectonic history includes multiple rifting phases from the Triassic to Early Jurassic. Exploration efforts have focused on closures of rotated fault blocks, with varied success. The Late Tithonian and Lower Cretaceous synrift sandstone reservoirs show high porosity and permeability, while source rock intervals with type II kerogen offer good-to-excellent potential.
The timing of hydrocarbon charge relative to the paleo-seal capacity of Cretaceous rocks is crucial for assessing the petroleum potential of the basin. A flow-path migration modelling tool evaluates scenarios involving reservoir charge, migration efficiency, lithological facies, net-to-gross maps, and seal capacity of Cretaceous and Jurassic sediments. This study examines how the sealing properties of these rocks over time impact hydrocarbon accumulation.
Modelling results indicate a consistent pattern in the filling history of structures, with initial vertical hydrocarbon movement due to ineffective cap seals, followed by the establishment of effective seals. The timing of this transition varies across different structures in the basin. Discrepancies between modelled and observed accumulations highlight the need for refined input parameters and methodologies.
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A Stochastic Workflow for Fault-Seal Characterization in Carbonate-Dominated Reservoirs
More LessAuthors P. WilsonSummaryFor faults hosted in siliciclastic-dominated reservoirs, there are established workflows that have been successfully used to address industry fault-seal characterization problems. These established workflows rely on the observation that clay mineral content of fault rocks in siliciclastic hosts has a strong influence on flow properties, with higher clay contents corresponding to lower permeability and higher capillary threshold pressure. However, fault-seal characterization in carbonate-hosted faults is more complex, partly because the faults typically have low clay contents and partly because of variability due to fracturing, cementation, and diagenesis. As a result, there is no equivalent established workflow for fault-seal characterization in carbonate reservoirs, despite estimates that approximately 60% of the world’s proven oil reserves and 40% of the world’s gas reserves are trapped in those reservoirs. There are several possible mechanisms that could allow carbonate-hosted faults to support significant static hydrocarbon columns or act as baffles to flow on production timescales, and rules to characterize these faults are required. The aim of this presentation is to propose a workflow for fault-seal characterization in these reservoirs, and demonstrate the workflow on a test data set.
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Downslope Variability in Seal Rock Characteristics in the Kazusa Forearc Basin, Japan
More LessAuthors K. Nifuku, S. Watanuki, Y. Iijima, Y. Kobayashi and M. ItoSummaryThis study investigated the variability of seal rock characteristics in the Pleistocene Kazusa Group, a forearc basin succession in Japan. Regional- to local-scale variations in mudstone characteristics, including mineralogy, seal capacity, and permeability, were examined using closely spaced onshore outcrops with precise chronostratigraphic correlation based on volcanic ash beds. The results show remarkable downslope variations in the seal rock properties, especially in the shelf margin to the slope environments. In contrast, basin floor mudstones exhibit only minor downslope variations. These findings can be used as a geologic analogue for potential carbon storage sites in the offshore part of the Kazusa sedimentary basin, where subsurface data remains limited. Furthermore, it can be utilized as a geologic analogue for areas with similar geologic settings, such as young siliciclastic-dominated successions formed in active margin basins.
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The Permeability and Petrophysical Properties of the Mercia Mudstone Group: A Heterogeneous Caprock
More LessAuthors S. Jones, D. Faulkner, R. Worden and Q. FisherSummaryThe Mercia Mudstone Group (MMG) has been cited as a potential caprock to CO2 storage, and is being considered as a potential host rock for the UK’s first Geological Disposal Facility. 18 samples of core have been collected throughout a continuous succession of MMG, and have undergone a range of experimental analyses in order to obtain controlling factors on permeability, permeability anisotropy and pressure sensitivity. X-ray diffraction (XRD) and petrographic analysis has shown a complex suite of detrital and early diagenetic minerals, resulting from an arid, continental environment of deposition. Mercury intrusion porosimetry (MIP) revealed a diverse range of mean pore throat sizes within the meso- to macroporous range, and porosity values ranging from 3.2% to 13.4%. These samples of MMG show a range in measured permeabilities, spanning 6 orders of magnitude. Permeability anisotropy within individual samples reach up to 3 orders of magnitude. More than 600 individual gas permeability measurements have been undertaken on these MMG samples, revealing the sealing potential of the different stratigraphic horizons present at depth. This extensive dataset will provide useful inputs for upscaling and predicating fluid migration under varying stress conditions.
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Initial Assessment of the Sealing Capacity of Caprocks in the Ionian Zone Reservoirs, Greece
More LessAuthors G. Adamopoulos, I. Vakalas, S. Bellas, S. Kokkalas, M. Perraki, V. Gaganis and E. StamatakisSummaryThis study evaluates the sealing capacity of various lithologies of the Ionian zone in Greece, through the analysis of 11 outcrop and 6 well samples using X-ray Diffraction (XRD) and Mercury Injection Capillary Pressure (MICP) techniques. Samples were collected from Epirus and Lefkas (Greece) and wells in Crete. XRD analysis identified mineralogical compositions, particularly focusing on evaporitic lithotypes. MICP testing, conducted with a Poremaster60GT porosimeter, assessed pore size distribution and capillary entry pressures, providing estimates of the maximum hydrocarbon (HC) and CO2 column heights each lithology could retain. Results showed that shale samples exhibited homogeneous microporosity and high sealing efficiency, capable of retaining significant oil and CO2 columns, constrained primarily by geomechanical properties. Mudstones demonstrated slightly larger pore sizes but retained excellent sealing potential for oil (up to 1315 m) and CO2 (up to 269 m). In contrast, evaporitic samples, impacted by weathering and reduced plasticity, exhibited wider macropore distributions and significantly lower sealing capacities (oil: 5–66.61 m; CO2: ∼1–13.26 m). These findings highlight the strong capillary sealing potential of shales and mudstones, while suggesting that evaporitic rock performance in outcrop samples may underestimate true reservoir conditions due to surface degradation and MICP limitations in microporosity detection.
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Permeability Anisotropy in Brittle Carbonate Fault Rocks
More LessAuthors E. MichieSummaryPermeability anisotropy of fault rocks has been documented in crystalline and clastic lithologies, but rarely within carbonates. Here, conditions for a permeability anisotropy to develop within carbonate fault rocks are documented. Forty-three fault rock samples plugged in three orthogonal directions were taken from eight faults in differing carbonate lithofacies. The permeability was measured, to assess if and to what extent a permeability anisotropy may develop. All samples showed some degree of anisotropy. However, a systematic major permeability anisotropy (up to 5 orders of magnitude) only occurred when the same or similar lithofacies were juxtaposed, where the lowest permeability was recorded normal to fault strike. Differences occurred in the highest permeability direction dependent on lithofacies. In deformation bands cutting high porosity grainstones, the highest permeability was inferred to be at a low angle to σ1, created by grain and pore alignment in the direction of transport. The highest permeability in faults cutting recrystallised carbonates varied from sub-parallel to σ1, to sub-parallel to σ2, owing to variations in Riedel shears and fracture orientation during multiple reactivation episodes. Predicting the permeability of a fault zone, including any directional permeability, is key for improved modelling of fluid flow pathways around faults in the subsurface.
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Microstructure of Mineralised Fracture Seals in Evaporitic Mudrocks
More LessAuthors K. Page, N. Forbes Inskip, A. Cartwright-Taylor and N. KampmanSummaryThe Mercia Mudrock Group is a sequence of siltstones, claystones, and evporites that is an extensive regional caprock and a prospective host rock for radioactive waste disposal in the UK. However, numerous natural fractures pose a leakage risk to infrastructure projects relying on MMG’s low permeability. Precipitation of evaporitic minerals into the fracture space lowers the permeability, restoring the seal. However, this specific form of sealing may create mechanical contrast between the fracture fill and the host mudrock, which can be exploited by stress perturbations, brought on by reservoir pressurisation, tectonic forces, and tunnelling.
This study uses optical microscopy, SEM, and EDX, to analyse the interface between fracture fill and host rock at a small scale, as to assess possible reactivation.
The main finding is that the interface is not always a discrete surface. Coarse grained mudrocks may share a cementing mineral with the fracture, which should limit the mechanical contrast, in contrast to clay rich mudrocks.
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Fault Geometric Characterization: Insights from Deep Learning Applied to High Resolution 3D Seismic Data
More LessSummaryThis study applies deep learning techniques to detect and characterize fault geometries in very-high-resolution 3D seismic data. Using a 3D U-net fault probability model, we investigated a shallow fault array within the Bjarmeland Platform in the southern Barents Sea. Structural analysis was conducted across key formations -Naust, Kolmule, Kolje, Stø, and Snadd-. The deep learning model enhanced the extraction of realistic fault shapes and the quantification of their geometric attributes—length, segmentation, and throw—in three dimensions. Results revealed a high degree of compartmentalization within the three deepest stratigraphic horizons. The fault array in this interval is characterized by predominantly orthogonal (∼90°) crosscutting relationships. While most faults exhibit relatively straight strike traces, some display more curvilinear geometries. Fault segmentation increases toward the base, and throw decreases toward the tip lines, with additional variability observed between specific stratigraphic levels. These findings underscore the value of data-driven approaches in minimizing interpretation bias, enhancing efficiency, and advancing our understanding of fault architecture and evolution in sedimentary basins.
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Pristine Seismic Amplitude Modeling Qualifying Fracture, Fault and Top Seals Capacity
More LessSummaryThis work presents a method for establishing weak reflectivities that indicate the hydraulic behaviors of potential fluids within and around these seals, as well as in damage zones. By utilizing concepts of pristine amplitudes and further inversion, we analyze gentle signal responses and texture patterns to understand fluid behavior in these structures. This approach not only helps identify potential hydrocarbon accumulations but also enhances our understanding of fluid interactions with various types of seals.
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Improvement of Structural Imaging and Reservoir Delineation in the Carpathian Foothills using Full Waveform Inversion
More LessAuthors M. Retailleau, P. Plasterie, H. Ayadi, J. Mitschler, S. Bezdan, L. Soveia-Iacob, M. Haghighi, C. Krezsek and J. OroszSummaryThe south of the Romanian Carpathian Mountains is characterized by an important thrust inclusion which is inserted inside the younger sediments of the Getic basin. This intrusion is the result of regional compressional constraints applied to the Getic foreland basin, occurring from the Eocene-Burdigalian until the Mid-Sarmatian. The so-called Burdigalian wedge shifted into the Getic basin along the Burdigalian salt detachment on top of the Moesian platform. The frontal part of the Burdigalian wedge is then an imbricate slice of the Upper Burdigalian strata.
In the past three years, several wide-azimuth seismic surveys have been recorded in the area to increase the knowledge of the subsurface. In this paper, we show how the latest seismic data acquisition and processing techniques significantly improved the imaging of the complex geological structures, enabling better delineation of prospects. We particularly show the benefits of Full Waveform Inversion (FWI) on two recent seismic imaging projects.
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Testing Up-Fault Leakage Criteria and Critical Stress Limits from Hydrocarbon Column Data in Active Tectonic Contexts
More LessAuthors J. Dutilleul, C. Wibberley, E. Caussarieu, R. Tozer and F. BourgeoisSummaryThis work illustrates the importance of capitalizing on hydrocarbon column heights trapped against active faults for evaluating the hydraulic and mechanical properties of faults. This is crucial for understanding fault behavior, evaluating CO2 containment and risks associated with fault reactivation and leakage.
A method allowing to determine the strength of active faults, or faults close to critical stress is presented, based on case studies evaluating hydrocarbon column heights in fault-bounded traps from the East African Rift and the Niger Delta. This method consists in comparing the in-situ hydrocarbon fluid pressure data with a theoretical fault slip threshold calculated using Mohr-Coulomb theory to determine the static friction coefficient best fitting the maximum pressure trend. The values determined match those obtained in laboratory shearing experiments on fault gouge material with a range of compositions, supporting this method for determining in-situ mechanical fault properties.
This work is directly applicable to CO2 storage screening studies for potential site selection where the trapping mechanism is a fault-bounded structure. It also helps in better understanding the hydraulic and mechanical processes involved in faulting by providing access to more realistic static fault properties to be used as input parameters in geomechanical models for CO2 storage containment.
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The Challenge of Booking Oil and Gas Reserves Across Faults: SPE vs SEGe
More LessSummaryEstimating and classifying oil and gas reserves are critical for investment decisions and regulatory compliance. The Society of Petroleum Engineers (SPE) provides widely recognised guidelines for reserves evaluation. At the same time, the Securities and Exchange Commission (SEC) sets the rules for public companies reporting reserves in the United States. Both guidelines address the challenges of geological faults, which can significantly impact reservoir compartmentalisation and hydrocarbon recovery. In essence, fault seal analysis provides critical information for accurate reserve estimation, particularly in faulted reservoirs. It helps reduce uncertainties, optimise field development strategies, and ensure reliable reserve reporting, essential for investors and regulatory compliance. The lessons we learn from comparing oil and gas reserves bookings will help us book CCS projects.
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Inclusion of Faults in Mining and Coal Seam Gas Environmental Risk Assessments
More LessSummaryEnvironmental Impact Assessment Statements (EIS) for Mining and Coal Seam Gas (CSG) projects are generally required to consider the potential hydrological impacts of faults on surface and near-surface groundwater assets. Three distinct end-member geological scenarios and outlines methods for characterising fault-related groundwater flow within a risk assessment context have been proposed ( Murray& Power, 2021 ).
This presentation considers the environmental hydrological aspects of risk assessment for mining and CSG developments. Following water resources and environmental risk assessment, we refer to features such as lakes, rivers, groundwater-dependent ecosystems, and valuable aquifers as groundwater assets or simply assets. Damage to a groundwater asset may include (for example) groundwater depletion or changes to the flow regime caused by mining and CSG development-induced pressure changes. Pressure changes may cause increased or decreased flow along pre-existing flow pathways, or cause the activation of new or previously unimportant flow paths. Should this flow be significant enough to degrade the asset, then the flow pathway is called a causal pathway.
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Integrated Characterization of Fault and Top Seal at Velocette: Understanding Trap Fill, Breach and Depletion Mechanisms
More LessAuthors W. Ahmed, K. Dindane and A. BiliutaSummaryExploration well 6607/3-1S (Velocette) marks the first significant penetration of sandy intervals within the Cretaceous Nise Formation on the eastern flank of the Utgard High. A 9-meter gas column was encountered in the upper section of the reservoir, with a total confirmed trap column of approximately 66 meters. Post-well studies focused on understanding the reason for reduction in column height from a pre-drill estimate of 240 meters to a post-drill column of 66 meters.
Laboratory analyses showed that the top seal could support a gas column of over 3700 meters, and mechanical seal strength indicated a headspace of more than 58 bar before failure. Therefore, the top seal is not the limiting factor for the trapped column. Fault membrane seal analysis revealed that while most of the Velocette relies on sand-shale juxtaposition, the areas relying on the membrane fault seal can accommodate a column larger than 140 meters. Thus, the fault membrane seal is not the limiting factor for the observed column. A fault reactivation study showed that the bounding faults are critically stressed under current pore pressure conditions, suggesting that any increase in pore pressure could induce fault reactivation.
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Fault Gouge Permeability Characterization and Implications for Fluid Migration During Fault Reactivation
More LessAuthors E. Skurtveit, M. Soldal, M.J. Høe, P. Betlem and E.S. PetrieSummaryFault zone permeability remains a challenging parameter to address both in outcrop and subsurface. Limited experimental data providing permeability measurements on natural fault rock samples from sealing parts of the fault are available. More data is needed to improve our understanding of fluid migration in faults and dynamic changes related to subsurface injection and the risk of fault reactivation and alteration of the seal capacity.
In this work we measure permeability for a natural fault gouge sample from Little Grand Wash Fault zone in Utah using a novel direct shear device. The low permeability measured is in line with a sealing fault core and supports field observations of the damage zone as the main pathway for CO2 migration. The shear loading phase of the experiment suggest a reduction in permeability during shearing and provides key data for improving our understanding of fault reactivation and effects on fluid migration.
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Improving Fault Behaviour Predictions using Empirical Rules for QC and Modelling of Fault Populations
More LessSummaryFaults are crucial in subsurface processes, affecting hydrocarbon accumulation, well planning, containment risks, and drilling safety. Accurate fault interpretation is essential, as errors can lead to unreliable subsurface predictions. While deep learning has improved fault interpretation, its effectiveness relies on geologically realistic training data and fault surface extractions.
We analyzed 4,754 faults from 44 3D seismic volumes across diverse geologic settings. Statistical compilations of fault dimensions, ambiguity, and density—relative to seismic volume quality—enable three key applications:
- Quality control of manual interpretations.
- Creation of realistic datasets for deep learning.
- Guidance for extracting discrete fault surfaces from inference volumes.
These volume-based tools, independent of horizon interpretations, enhance fault analysis accuracy, supporting safer and more efficient subsurface operations.
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Depositional and Diagenetic Controls on the Spatio-Temporal Variability of the Triassic Mercia Mudstone Group, UK
More LessAuthors J. McEvoy, R. Worden, D. Faulkner, J. Griffiths, N. Smith and V. TsitsopoulosSummaryThe Middle-Upper Triassic Mercia Mudstone Group (MMG) of England and Wales, and equivalent units on the UK offshore continental shelf, is a successful top seal to hydrocarbon reservoirs and is now a potential host rock for radioactive waste disposal and top seal to Carbon Capture and Storage (CCS) reservoirs in the UK. A significant challenge for these projects is that the MMG is both vertically and laterally heterogeneous. The distribution and causes of heterogeneity are poorly understood. We will here show that this variability has arisen from spatial-temporal changes in depositional environments combined with complex differences in the temperature-time history of major UK Triassic basins. This research therefore takes an integrated approach by combining published compositional, sedimentological and burial diagenetic data to synthesise the depositional and diagenetic controls on the spatio-temporal variability of this heterogeneous rock. As well as improving general understanding of the variability of the MMG, the findings of this research provide crucial insights into the representativity of natural analogues for CCS and radioactive waste disposal projects in the UK.
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