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- Volume 42, Issue 2, 2024
First Break - Volume 42, Issue 2, 2024
Volume 42, Issue 2, 2024
- Technical Article
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DC Resistivity Inversion Using Conjugate Gradient and Maximum Likelihood Techniques with Hydrogeological Applications
AbstractThis study introduces a DC 2D inversion algorithm that employs conjugate gradients relaxation to solve the maximum likelihood inverse equations. The adoption of the maximum likelihood algorithm was motivated by its advantage of not requiring the calculation of electrical field derivatives. While the inversion algorithm based on the maximum likelihood inverse theory has been extensively described for 3D DC inversion using finite differences modelling, its application in the 2D finite element method has received limited attention. A significant difference between 3D finite difference modelling and 2D finite element methods lies in the integration variable lambda. In our 2D case, the electrical potential is initially calculated in the Laplace and Fourier domains, which include the stiffness matrix. However, to obtain the stiffness matrix in the Cartesian domain, we had to develop a suitable transformation method since no existing resources in the literature addressed this specific condition. In this study, we successfully transformed the stiffness matrix using a similar approach to the potential calculation. The results obtained from synthetic and real models demonstrate the method’s potential for various applications, as exemplified by the hydrogeological study presented in this work.
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Innovative Environmental Monitoring Methods Using Multispectral UAV and Satellite Data
Authors Benjamin Haske, Tobias Rudolph, Bodo Bernsdorf and Marcin PawlikAbstractProtecting natural and near-natural ecosystems is becoming increasingly important in an ever more densely populated and intensively used earth surface. Climate change-induced extreme weather events have accelerated the environmental degradation that has been taking place for centuries. Comprehensive and precise environmental monitoring is therefore essential, especially around mining, post-mining and industrial sites. Traditional in-situ measurements are inadequate for wide areas, necessitating the integration of satellite and unmanned aerial vehicle (UAV) remote sensing data for a more comprehensive monitoring.
This multi-level approach utilises satellites for large-scale and high-temporal remote sensing and UAV data for medium-area and high-precision monitoring, while in-situ measurements serve as validation for both data sources. Different case studies at the Research Center of Post-Mining demonstrate the approach’s effectiveness in geomonitoring post-mining processes and risk management in the oil and gas industry.
Integrating diverse data sources enables comprehensive monitoring and analysis, enabling the creation of user-friendly web applications to facilitate efficient risk management decisions. This multi-level monitoring concept offers an efficient approach to understanding and addressing environmental changes and risks in various industries and conservation projects.
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- Special Topic: Digitalization / Machine Learning
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Lessons Learnt for Tuning a Machine Learning Fault Prediction Model
Authors Hadyan Pratama, Matthew Oke, Wayne Mogg, David Markus, Arnaud Huck and Paul de GrootAbstractWe describe a series of experiments designed to improve fault likelihood predictions of a pre-trained machine learning model on an unseen dataset with real fault interpretations. The goal is to establish a best practice workflow for tuning fault prediction models. The model is a 3D model that is tuned by training with a Masked Dice loss function on 2D interpretations. In our experiments we vary the number of interpreted sections in the training set and vary the number of epochs to train the model. We also compare continuous training versus transfer training. To optimise transfer-training we conduct experiments with freezing different parts of the model.
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Ensemble History-Matching Workflow Using Interpretable SPADE-GAN Geomodel
Authors Kristian Fossum, Sergey Alyaev and Ahmed H. ElsheikhAbstractEnsemble history matching adjusts multiple geomodels used for reservoir simulation, conditioning them to historical data. It reduces and quantifies the uncertainty in the unknown model parameters to increase the models’ reliability for decision support. In this study, we adapt the latest generation of generative artificial intelligence algorithms, SPADE-GANs. In geosciences, Generative Adversarial Networks (GANs) learn to simulate complex geological patterns. SPADE (SPatially Adaptive DEnor-malisation) layers in the GAN generator learn conditioning to the coarse geological structure provided as coarse-scale maps, enabling explainable output, stable training, and higher variability of resulting outputs. Our statistical method, an iterative ensemble smoother, assimilates data into an ensemble of these maps, interpreted as the channel proportions. This Bayesian data assimilation conditions the ensemble of GAN-geomodels to a combination of well data and flow data, thus extending the usability of pretrained SPADE-GANs in subsurface applications. Our numerical experiments convincingly demonstrate the method’s capacity to replicate previously unseen geological configurations beyond GAN’s training data. This proficiency is particularly valuable in data-scarce scenarios typical for renewable geo-energy, where the GAN captures realistic geology, but its output geomodels must be adjusted to match observed data. Furthermore, our fully open-source developments lay the foundation for future multi-scale enhancements of history matching workflows.
The extended abstract for this article is published in the proceedings of the Fifth EAGE Conference on Petroleum Geostatistics (November 27–30, 2023; Porto, Portugal).
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Geomechanical Parameter Derivation while Drilling in Unconventional Plays: a Combination of Surface Drilling Data, Gamma Ray Data, and Machine Learning Techniques
Authors Marvee Dela Resma and Ivo ColomboAbstractThis study illustrates a field application of a robust and reliable approach for assessing geomechanical parameters during drilling operation or as a post-mortem analysis. The methodology leverages surface logging drilling data (such as Rate of Penetration, Rotation Per Minute, Weight on Bit, Torque, Standpipe Pressure, and Flow rates) along with well log data (including Sonic log, Bulk Density log, and Gamma Ray log) as input of the methodology. This model is grounded on the integration of various data processing techniques and machine learning algorithms (encompassing Multiple Linear Regression, Support Vector Regression, Random Forest, Artificial Neural Network, and XGBoost), ensuring a comprehensive and accurate evaluation of geomechanical parameters in the area under evaluation.
The methodology is applied to a dataset of six wells drilled in the same geological units of an area located towards the eastern limit of the Neuquén Basin, north of the ‘Dorsal de Huincul’ (Gonzalez et al. 2016). The results associated with Young’s Modulus, Density, and UCS, here presented, provide evidence of its successful use in a challenging geological context such as the unconventional plays in Argentina.
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A Framework for Mineral Geoscience Data and Model Portability
More LessAbstractWe have developed a data structure called GEOH5 with the objective of integration and storage of geological models, data, and metadata where dissemination, ease of access, and persistence are required without commercial encumbrance. Our emphasis is on the needs of the mineral industry which, unlike the upstream oil and gas industry, otherwise lacks common data exchange formats with a scope encompassing most exploration and production data types. Although only a few years old, the data structure is already in use by many thousands of users with increasing acceptance across mineral geoscience and engineering. This includes industry, academia, and geological surveys that use GEOH5 as a documented, public, easy-to-use, vendor-neutral, and permanently accessible means of storage and communication. GEOH5 is open source and free to use. It is based on open-source HDF5 technology because of its many advantages: wide acceptance across numerous data-intensive industries, self-describing behaviour through integration of data and metadata, fast I/O, excellent compression, file merging, cross-platform capability, unlimited data size, and access to libraries in a variety of programming languages. It provides professionals, researchers, and the public at large with a robust means of managing, exchanging, and visualising large quantities of diverse mineral geoscience and engineering data.
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Volumes & issues
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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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