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79th EAGE Conference and Exhibition 2017 - Workshops
- Conference date: 12 Jun 2017 - 15 Jun 2017
- Location: Paris, France
- ISBN: 978-94-6282-219-1
- Published: 12 June 2017
81 - 100 of 144 results
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Play mapping in the East Java Basin, Indonesia: A Methodology for Future Exploration in
Authors I. Longley, C. Kenyon, A. Livsey and J. GoodallThe East Java basin of Indonesia is a long established petroleum province notable for having delivered significant volumes in the modern exploration era. The basin contains an unusually large variety of clastic and carbonate reservoir-seal pairs reflecting tectonostratigraphic settings ranging from extensional rift basins to stable platform areas to compressional and wrench-related inversion reflecting proximity to the convergent margin to the south. The large variety of plays and potential for further discoveries make the basin an ideal candidate for a systematic split-risk CRS mapping approach to determine remaining exploration potential both within proven and unproven play areas in both conventional and stratigraphic traps. CRS maps and stacks have been produced for nineteen plays over the greater East Java area as far north as the Assem Assem Basin and eastwards to the southwestern arm of Sulawesi. This methodology is repeatable and applicable to other western Indonesian Basins, as the focus shifts towards traps with significant stratigraphic trapping components and should help increase our understanding of the factors responsible for failure, hopefully leading to better predictive capabilities for success.
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Evaluating a vintage Play Fairway Exercise using subsequent exploration results: did it work?
Authors F. Lottaroli, J. Craig and A. CozziIn this paper we compare the results of a vintage (1995) Play assessment of onshore Colombia (Upper Magdalena Basin) with the actual outcomes of exploration activity over the following 20 years, through re-construction of the vintage risk assessment in GIS and re-computing yet to find using different methodologies. The vintage play chance maps were constructed largely based on geological concepts and guesses, supported by outcrop geology and sparse subsurface data (mainly wells). Methodologies (modern and vintage) and results of YTF calculation are compared and discussed.
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Multidisciplinary Integration of Prospectivity and Value in Play Analysis - An example from onshore Kazakhstan
Authors P. Ventris, J. de Jongh, E. Dujoncquoy and S. ArcherBasin evaluations necessarily focus significant effort on the sub-surface. The typical workflow involves building an integrated understanding of the basins structural origin and development, the sedimentary fill and the movement of fluids within the basin. Plays are then defined and play analysis typically undertaken based on this foundation of a thorough understanding of the basin architecture and fill. For the context of this presentation a play is defined as a reservoir – seal pair with the potential to access charge from one or more of the predicted or proven source rock intervals.
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A map-based, integrated geological and economic approach for play analysis
Authors K. Nifuku, K. Ogino, K. Nakaoka, Y. Okano, T. Ito and T. TodorokiPlay based exploration is an effective approach in the exploration of emerging and frontier plays in a basin. It is essential to evaluate and understand geological potentials of the plays, for instance geological risk and field size, together with their economic potential in order to identify the best areas to invest. This paper introduces a workflow of a map-based, integrated geological and economic approach for play analysis, which is based on our assessment in the deepwater Northern Gulf of Mexico.
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Extension of the Apulian Platform in the Northwest Greek Offshore: paleogeography update and impact on hydrocarbon prospectivity- Greece.
Authors V. Carayon, L. Montadert, J. Allard, A. Fournillon and et allThis presentation is about shallow water carbonate platforms and associated build-ups present the NW Greek Offshore. Its goal is to delineate the offshore extension of the Apulian platform-type series resting over the western edge of the Adria microplate present within the convergent boundary zone between the African and Eurasian plates. This study, based on careful seismic stratigraphy analysis of a multiclient 2D “Broad band” data acquired and processed by Petroleum Geo-services, has enabled to identify two shallow water isolated platforms between the Otranto Strait and the Strophades Islets. The northern “Apulian Ridge” and the southern “Strophades Ridge” present on either side of the Kefalonia dextral strike slip fault, are atoll-like rimmed carbonate platforms that developed in passive margin condition during the Mesozoic. During the Cenozoic these atolls were topped by two sets of shallow water build-ups attributed to (1) Upper Oligocene-Lower Miocene, quite unique in the Mediterranean as they formed during the Alpine orogeny climax, and (2) Upper Miocene, demised during the Messinian Salinity crisis. Despite crucial unknown about rocks age and properties, some of the identified Mesozoic build-ups or resedimented base of slope carbonates and Cenozoic fringing build-ups represent future valuable exploration targets.
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Play Analysis of the Gamtoos Basin, off the south coast of South Africa: From Concept to Portfolio
Authors A. Davids, C. van Bloemenstein and J. RouxA play analysis was carried out in the underexplored Gamtoos Basin, South Africa. A total of 10 wells were drilled of which five encountered oil and/or gas shows. An integrated approach, incorporating geology, geophysics, sedimentology and geochemistry led to the mapping of petroleum elements, including source, reservoir, charge and seal risk as well as the geological chance of success (Pg). This culminated in the identification of 80 leads which were ranked from low to high risk. Full risk analysis of the Synrift 1a play fairway is described in detail while the portfolio of the other plays are only summarised. This analysis resulted in a better understanding of the regional geology, structural development and the hydrocarbon potential of the basin.
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A Chance Calculus for Play-Based Exploration
By C. StabellThis paper presents a rules-based calculus for prospect chance estimation. A key idea is that estimates are based on a combined categorization of our knowledge level (DATA dimension) and our model of the geological context (MODEL dimension). We call it a chance calculus that combines data and judgement with simple rules. Earlier work (Milkov, 2014) is extended by using two-level chance rules that distinguish between shared play chance estimates and conditional prospect chance estimates as well as by a second separate step that handles seismic anomalies. The chance calculus provides estimates that are consistent and cover all chance factors and all conventional exploration situations. Explicit MODEL categorization not only provides a transparent, unambiguous basis for the chance estimates, but also eliminates double risking between shared and conditional chance estimates.
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How to counter the effects of upside bias in prospect inventories used for yet-to-find estimations
By D. QuirkDownside discovery sizes result from when the pre-drill prospect model fails and occur in as much as 50% of successful exploration wells. This paper shows a way of incorporating the downside in prospect evaluations, based largely on historical data.
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Production in the USA. How long will it take to decline by half if there is no new drilling?
Authors H. Kuzma and J. Conradson1.3 million individual well production forecasts are aggregated to estimate the time it will take for production to decline by half in the USA if no new wells are drilled. Drilling is currently less than a third of its 2014 levels. Considerable capital is required to replace declining production, capital which might not be readily available. Half production for the USA is forecast to be hit before 2022. For the shale basins such as the Bakken and Eagle Ford, it will be in the next 1 - 3 years. This means that hundreds of thousands of new wells will have to be drilled to restore production to 2014 levels. The limiting factor in exploiting American shale reserves may be access to capital, not geology.
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Progresses in the exploration of structural uncertainties
Authors G. Caumon, G. Godefroy and F. LallierThis talk provides some motivations for generating multiple stochastic structural models and reviews recent trends in stochastic structural modelling methods. We discuss in particular the main advances and challenges to confront spatial data and structural concepts in cases where multiple structural scenarios with different numbers of faults and different fault connectivity mush be considered. We also propose a way to formulate the stochastic structural modelling problem and discuss its potential to manage many types of spatial observations, to integrate several types of structural concepts and to explore structural uncertainties in an organized way.
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Statistical inversion of seismic data for reservoir property estimation: analytical vs. numerical approaches
By D. GranaThe estimation of reservoir properties from seismic data is a mathematical inverse problem and can be solved by combining geophysical modelling and inverse theory. Successful results have been obtained using either deterministic or statistical methods. One of the advantages of statistical approaches is the uncertainty quantification of the model parameter predictions. Bayesian inverse methods have been applied to seismic inverse problems to predict the point-wise posterior distribution of elastic attributes or petrophysical properties. In this work, we present several examples of Bayesian inversion for reservoir characterization applications.
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Conceptual geological models and modelling tools for assessing fault-related uncertainties in flow from conventional clastic reservoirs
By T. ManzocchiAttempts to consider fault-related parameters during convergence of a flow model towards a history-match will, at best, allow fault rock permeability to be altered systematically, often as a function of the local Shale Gouge Ratio (SGR). Several published examples now exist of history-matched field-specific SGR-to-permeability relationships, but all have one thing in common: they derive from Brent-province reservoirs. Why? Is there something characteristic about post-depositional faults in deltaic sequences (like the Brent province) that makes the SGR approach more likely to succeed in this setting than in others (e.g. deep marine sequences containing syn-depositional faults)? Empirical evidence and geomechanical models suggests that different aspects of faults are likely to be significant on reservoir-scale flow in different geological settings, and there may be good reason to expect, a priori, different fault characteristics (e.g. sub-seismic fault segmentation and discrete shale smears) to dominate uncertainty on flow in different reservoir types. New tools are required to handle these characteristics. One important conceptual difference between the existing fault property modelling tools and the future tools needed to handle a wider range of fault-related uncertainties, is the requirement to represent heterogeneity explicitly, rather than as an average property captured by an SGR-to-permeability relationship.
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Facies classification using machine learning: lessons from SEG-ML contest
By M. BlouinNew resources exploration and exploitation sites collect at high resolution and rate multiple sources of data, generating considerable amount of information to process and eventually, interpret. Newly developed Machine Learning algorithms can help overcoming this challenge to gain better insight on data and resources. As the latter is hot topic right now in geoscience, Matt Hall, Editor of Leading Edge’s Geophysical Tutorial launches a contest for facies prediction in 2016 October issue. For this purpose, wireline logs and geological facies data from nine wells in the Hugoton natural gas and helium field of southwest Kansas (Dubois et al. 2007) were made available, with facies in two wells being kept blind to contestants. With contributions from data scientists from all over the world, the best score achieved was a little over 63% for the automated prediction of 9 different facies. Submissions included a dozen different algorithms, but ensemble methods (Gradient Tree Boosting, Random Forest) proving to be the most successful ones. Also, feature engineering (the extraction of more information from the variables) turned out to be the key aspect for successful prediction. In addition, comprehensive interpretation of the contestants results showed that prediction uncertainty was roughly about 4%.
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Accounting for diagenesis in the simulation of reservoir properties. How to manage uncertainties on the data?
Authors B. Doligez and H. BeucherThe objectives of this paper are to address the problem of integration of data corresponding to different physics and different supports to construct a geological static model. In fact, diagenesis and petrophysical properties are characterized and quantified from laboratory analyses, observations of thin sections, tests on cores while values are needed to populate cells of the geological model (metric to decametric size). At present, mean characteristics of these properties are generally attributed to the dominant facies in these cells, despite their more complex distribution existing from experimental measurements at a smaller scale. We illustrate on different examples derived from real data some ways to integrate this variability to obtain more realistic distribution of the reservoir properties. Moreover, the hypotheses on the physical process of diagenesis and on its continuity through different facies can be tested through different spatial model in order to quantify the final uncertainty on the resulting model. These points will be addressed using the Pluri-Gaussian Simulation method with parameters adapted to each type of uncertainty.
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Some geostatistical models for filling heterogeneous reservoir with petrophysical properties
Authors D. Renard and H. BeucherOne of the main challenges of Geostatistics in reservoir characterization is to populate a portion of 3D earth model with rock properties. Their spatial characteristics are analyzed along the stratigraphic reference system where the variogram is modeled. A base case estimation (kriging) may be sufficient, or complemented by stochastic simulations for a sensitivity analysis. Sometimes properties present multimodal distribution reflecting the heterogeneity within the studied stratigraphic domain. Therefore it makes sense to look for explanatory co-variables, such as the lithotype. Then we simulate the spatial organization of different lithotypes first (using categorical simulation) and afterwards populate each lithotype with the rock property following the rock- dependent spatial characteristics. The previous workflow, which relies on the independence between lithotype and rock property, may not be relevant if the samples show a border effect when crossing the lithotype border. Some statistical tools are introduced to check the relevance of this assumption, such as the transition probabilities and the contact analysis. The border behavior is also checked after the initial simulation outcome has been upscaled. Some stochastic joint models of lithotype and rock property are conceived to reproduce the presence or absence of borders, conditioned to sample data.
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Constraining the history match using 4D seismic data: how far can we go?
Authors C. MacBeth and R. ChassagneA key direction for history matching (HM) or close-the-loop exercises is the incorporation of time-lapse (4D) seismic data into our workflows.
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Rapid forecasting of uncertain reservoir responses using functional data analysis
By C. ScheidtUncertainty in future predictions of oil reservoirs is traditionally obtained via a history matching procedure which generates a set of reservoir models that match the available data to within a user defined tolerance. The process of creating history-matched models can be a very expensive and difficult task, and often needs to be repeated when new data is obtained. In this presentation, we propose a diagnostic tool which indicates rapidly to what extent the posterior uncertainty on the forecast will be reduced, if at all, by the data. To do so, instead of generating models that match the data, we propose to estimate the relationship between the historical and forecast variables. This relationship is then used when new historical observations are available to update statistically the uncertainty on the forecast. Through this procedure, an estimate of Bayesian posterior forecast uncertainty can be obtained without requiring history matching, indicating if the data is indeed informative on the prediction variables.
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Model aggregation for production forecasting
By G. StoltzI will review in this talk a machine-learning technique called robust online aggregation of predictors. This setting explains how to combine base forecasts provided by ensemble methods. No stochastic modeling is needed and the performance achieved is comparable to the one of the best (constant convex combination of) base forecast(s). These techniques have been applied to a variety of data sets (includign electricity consumption or echange rates) but I will focus in this talk on the forecasting of the production of oil and gas.
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Identification of the key geological uncertainties by unconventional reservoirs features analysis
Authors A. Pishchuleva, O. Gorbovskaya and E. ZhukovskayaProspects of the study field are linked with the reservoir engineering of low permeability formations of lower Jurassic - J15, J14. It is essential to have an accurate prediction of geological parameters for optimal reservoir engineering system for such unconventional reservoirs. The main problem at the study field is the lack of direct methods for the reservoirs definition (poor well logging), the uncertainty of quantitative interpretation, of the lateral variability, the inability to forecast the reservoir properties according to the current seismic data processing. Through the core, logs and seismic data complex study were set the wide area spreading of sediments as reservoirs and non-reservoirs. It can be noticed certain reduction of the J15 formation total thickness on the elevations. The paper contains the prerequisites for the formation reservoir properties and their differentiation in the geological section, lithogenetic factors associated with tectonic processes and the basic geological uncertainties.
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Spectral Decomposition and Attribute Analysis of Gharif Formation, North Oman
Authors S. Narasimman and M. Al-GhannamiThe aim of this study is to map sand distributions and faults within Upper Gharif by extracting attributes using the seismic, acoustic impedance, spectral decomposition and RGB blend. Sand distributions and faults within Upper Gharif are mapped by extracting attributes. In this study attributes were extracted using spectral decomposition, RGB blending and acoustic impedance volumes to distinguish between sands and shales. First using spectral decomposition in which the seismic trace is decomposed into mono-frequencies in order to observe the amplitudes related to each frequency in the seismic. Using Trap Search Engine attributes of mono-frequencies are generated and compared with the well data. In addition using RGB blend, best mono-frequency volumes, based on sand thickness and well calibrations, are combined for better analysis.
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