First Break - Latest issue
Volume 44, Issue 2, 2026
- Technical Article
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Reservoir Resistivity Modelling for CSEM Interpretation and Model Building
More LessAuthors Daniel Baltar PardoAbstractIn controlled-source electromagnetic (CSEM) interpretation and model building, generating accurate resistivity models of the Earth is essential. When hydrocarbons are present, this process requires developing reservoir resistivity models, which typically involve linking expected hydrocarbon saturation to reservoir resistivity at the field scale. In predrill scenarios — where no well logs or core data are available — field-scale resistivity expectations must be derived through modelling. However, these models often rely on simplifying assumptions, such as constant reservoir properties combined with well-established resistivity-saturation relationships. While these relationships are valid at the core or log scale (cm to m), their applicability at the field scale (m to km) is questionable.
This paper examines the impact of these simplifying assumptions and modelling techniques, with a focus on the consequences of neglecting hydrocarbon saturation variability. We explore the relationship between sediment resistivity and water saturation across scales, from core and log to field scale. Our findings highlight the significant role of saturation variability, driven primarily by pressure build up with height and reservoir property variations. To address these challenges, we propose a workflow that accounts for the main sources of variability, enabling the upscaling of core-scale relationships to the field scale. We illustrate our proposed methodology using an example from the North Sea.
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From Discrete Element Method (DEM) to 2D Synthetic Seismic Modelling
More LessAuthors Roderick Perez and Stuart HardyAbstractFault complexity in seismic data can be more accurately represented by integrating geomechanical simulation and forward seismic modelling. A multi-layer stratigraphic model subjected to progressive deformation was constructed using the Discrete Element Method (DEM). Acoustic impedance fields derived from mechanical evolution provided the basis for calculating vertical reflection coefficients, which were then convolved with zero-phase Ricker wavelets using a 1D approach to produce synthetic seismic sections. Compared to conventional planar-fault representations, the resulting images display intricate reflector terminations, and amplitude dimming associated with distributed fault damage and rotated blocks. These results highlight that even a single fault, when modelled with physics-based deformation, produces richer and more varied seismic responses than matrix-deformation/warping approaches used to create labelled training datasets, providing a more geologically reliable basis for AI fault-segmentation and interpretation.
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- Special Topic: Digitalization / Machine Learning
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From ‘Text Soup’ to a Trusted AI Foundation; Semanticising OSDU Data for a Multi-Attribute Future
More LessAuthors Dr Thibaud Freyd and Dr Raphael PeltzerAbstractThe oil and gas industry continues to digitise subsurface data, yet much of the high value information remains trapped in unstructured formats such as scanned final well reports, daily drilling reports, and biostratigraphy analyses. While the OSDU® Data Platform standardises structured datasets, unlocking value from unstructured records requires semantic enrichment and rigorous security.
This article presents a scalable, entitlement first Retrieval Augmented Generation (RAG) architecture that transforms unstructured, OSDU referenced content into actionable intelligence. The approach combines document reconstruction, header aware chunking, and hybrid retrieval - Best Matching 25 (BM25) + vector search fused via Reciprocal Rank Fusion (RFF) – with preretrieval filtering that maps Entra ID identities to OSDU Access Control Lists (ACLs). On a curated 250 question pilot set representative of subsurface workflows, semantic reconstruction and hybrid retrieval improved recall and precision by up to 20% relative to a naïve baseline, with reported reductions in time-to-answer. The article clarifies how RAG grounds generation and how ReAct agents can orchestrate multistep decision support on top of a trusted foundation.
Overall, the study outlines a practical path from unstructured ‘text soup’ to compliant, auditable answers suitable for enterprise deployment at scale.
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From Metadata to Embeddings: Enabling Agentic AI for Subsurface Intelligence
More LessAuthors B. Lasscock, D. Arunabha, L. Chen, M. Gajula, K. Gonzalez, C. Liu, B. Michell, S. Namasivayam, V.S. Ravipati, A. Sansal, M. Sujitha, G. Suren and A. ValencianoAbstractThis article presents a practical framework for AI-assisted subsurface data access based on explicit data representations, agent-based workflows, and efficient information retrieval. We demonstrate large-scale conversion of SEG-Y archives into self-describing MDIO v1 datasets and present a case study on agent-driven reconstruction of seismic metadata from legacy text headers. A second case study evaluates embedding-based retrieval across acquisition and processing reports, showing that vector quantisation and graph-based indexing enable low-latency, relevance-driven search. These capabilities are integrated into an interactive, multi-agent system that supports natural-language analysis and coordinated access to structured and unstructured subsurface information.
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Volumes & issues
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Volume 44 (2026)
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Volume 43 (2025)
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Volume 42 (2024)
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Volume 41 (2023)
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Volume 40 (2022)
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Volume 39 (2021)
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Volume 38 (2020)
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Volume 37 (2019)
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Volume 36 (2018)
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Volume 35 (2017)
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Volume 34 (2016)
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Volume 33 (2015)
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Volume 32 (2014)
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Volume 31 (2013)
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Volume 30 (2012)
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Volume 29 (2011)
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Volume 28 (2010)
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Volume 27 (2009)
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Volume 26 (2008)
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Volume 25 (2007)
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Volume 24 (2006)
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Volume 23 (2005)
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Volume 22 (2004)
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Volume 21 (2003)
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Volume 20 (2002)
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Volume 19 (2001)
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Volume 18 (2000)
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Volume 17 (1999)
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Volume 16 (1998)
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Volume 15 (1997)
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Volume 14 (1996)
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Volume 13 (1995)
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Volume 12 (1994)
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Volume 11 (1993)
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Volume 10 (1992)
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Volume 9 (1991)
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Volume 8 (1990)
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Volume 7 (1989)
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Volume 6 (1988)
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Volume 5 (1987)
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Volume 4 (1986)
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Volume 3 (1985)
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Volume 2 (1984)
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Volume 1 (1983)
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What is DMO?
Authors S.M. Deregowski
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