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- Volume 39, Issue 9, 2021
First Break - Volume 39, Issue 9, 2021
Volume 39, Issue 9, 2021
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Adaptive subtraction using a convolutional neural network
Authors Amarjeet Kumar, Hampson Gary and Tom RaymentAbstractAdaptive subtraction is a well-established routine technique in seismic data processing that relies on being able to match, in some sense, one dataset to another. It is a necessary part of many processing steps such as de-noising and de-multiple. The same matching methods are also used for advanced imaging steps such as non-stationary estimation of the Hessian as part of image-domain least-squares migration. Predictions of noise are often not as accurate as we would like because there are often shortcomings in the prediction method and because pragmatic acquisition compromises are made. The ubiquity of adaptive subtraction in the seismic processing workflow means there is always motivation to improve its performance. In this work, we propose a deep-learning approach for the adaptive subtraction of predicted multiple models from the input recorded data. It turns out that it is straightforward to use deep-learning networks to perform adaptive subtraction and as a result, benefit from the power of complex non-linear filters. Inspired by the idea of a convolutional autoencoder, we have developed a supervised convolutional autoencoder for adaptive subtraction. We demonstrate the proposed approach on synthetic and field data examples and compare the results using conventional adaptive subtraction methods to illustrate the effectiveness of our approach.
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Full-azimuth differential seismic facies analysis for predicting oil-saturated fractured reservoirs
Authors Alexander Inozemtsev, Zvi Koren, Alexander Galkin and Igor StepanovSummaryThis work presents a novel technology for azimuth-dependent facies analysis (Facies Analysis versus Azimuth — FACIVAZ) to improve the prediction of hydrocarbon-saturated permeable fractures in terrigenous carbonate reservoirs. The analysis is performed in the depth domain along high-resolution, full-azimuth, angle domain common image gathers created by the EarthStudy 360™ Local Angle Domain (LAD) imaging system. The amplitude and phase preservation of the seismic reflectivities obtained by this imaging system is crucial to the proposed analysis. Prior to the facies analysis, the general orientation and intensity of the target fracture systems are analysed and characterized by azimuth-dependent velocity and amplitude analyses (VVAZ and AVAZ) performed along these LAD gathers. The remaining effects of the azimuth-dependent (and frequency-dependent) absorption and dispersion on the LAD gather events are then detected and further connected to the rate of the existing oil-saturated fractures within the reservoirs. The examples presented in this article show the effectiveness of the proposed FACIVAZ technology in accurately predicting the distribution of seismic facies in target production areas associated with oil-saturated fractured reservoirs in Western Siberia and Middle Volga. The results strongly agree with the corresponding facies characteristics measured in the boreholes along the reservoir area, and therefore serve as valuable information for the drilling decisions of new wells.
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Integrating rock physics, PP-PS joint inversion and time-shifts to improve quantitative interpretation of time-lapse fluid and pressure changes
Authors Andrea Damasceno, Ali Tura, Guilherme Vasquez, Wilson Ramos and Paula DarivaAbstractIn this study, we show how to overcome the challenges of reliably estimating subtle 4D elastic property changes from seismic acquisitions just one year apart. We show that this is possible thanks to: 1) availability of highly repeatable seismic data and permanent reservoir monitoring (PRM); 2) the methodology for building 4D rock physics models that quantify 4D uncertainties related to seismic repeatability, 3) improving the quality of time-lapse estimates, especially at impedance S, due to the application of the 4D PP-PS joint inversion. This article summarizes the work of quantitative 4D interpretation by reporting how to build 4D rock physics models, how to estimate 4D elastic attributes (joint inversion of PP-PS data) and how the integrated interpretation of these results is performed. To validate the 4D interpretation, the results were compared to the production data from the injector and producer wells and to the outputs of the flow simulator. The integrated analysis shows how injection and production operations affect the reservoir properties, indicating preferred paths for water flow, the role of faults in reservoir hydraulic connectivity, regions where hydrocarbon production caused depletion, areas pressurized by water injection, and even the effect of the salinity contrast between the injection water and the brine. The application of this methodology allows updates to the simulation model that will affect future decisions.
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Multi-azimuth multisensor quantitative interpretation: a South Viking graben case study, Norway
Authors Cyrille Reiser and Eric MuellerAbstractThe quest for any geoscientist trying to build an accurate reservoir model, or to estimate petroleum resources, has always been to extract reliable, high-quality reservoir properties from seismic data in an efficient manner. This article looks at the reservoir characterization of a recently acquired and processed multi-azimuth multisensor survey in the prolific South Viking Graben, offshore Norway, an area that has delivered numerous significant successes in multiple plays over the past decade. We focus our analysis on the quantitative interpretation of the various stratigraphic intervals ranging from the Tertiary to the Permian reservoir levels by integrating the seismic data with a significant number of wells within and around the area of interest. A proprietary, interactive, regional rock physics modelling tool was used to analyse the available well log information and rapidly assess the expected elastic properties variation and the prestack seismic responses for a range of changes in local reservoir conditions. The case study presented here highlights how newly acquired broadband seismic data, integrated with regional well information, successfully addresses some known regional and near-field exploration challenges. The project is continuing, however, very promising results have already been achieved for the evaluation of reservoir and trapping styles for existing fields and discoveries and also regarding the mapping of new opportunities for future near-field exploration activity.
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Breaking the seismic 4D ‘image’ paradigm of seismic monitoring
Authors Habib Al Khatib, Yessine Boubaker and Elodie MorganAbstractSeismic imaging techniques were designed for exploration. To better image the subsurface, the industry developed high-resolution 3D seismic monitoring methods which used systems able to record hundreds of thousands of channels simultaneously. In the 1990s when the need for reservoir monitoring appeared, repeating the seismic image over time was a natural progression and delivered high quality results. Later, to increase the detection threshold, expensive permanent systems have then been installed enabling world record detection threshold levels.
Yet, since then, improvements in seismic structural images combined with reservoir dynamic simulations provide more accurate predictions. With reduced uncertainty, lighter seismic monitoring approaches could be considered: focused seismic monitoring could provide more frequent observations at strategic subsurface locations to rapidly validate or invalidate flow simulations.
In this article we present a focused 4D seismic monitoring method that predicts the optimal source and receiver locations for the monitoring of strategic areas, capitalizing on existing 2D/3D seismic and reservoir knowledge. Such a light acquisition set-up using conventional equipment is agile enough to enable frequent detections of changes in several locations.
The method is illustrated using two field cases that show excellent correlation results with observation well data which illustrate a better reservoir understanding of dynamics arising from our approach.
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Volumes & issues
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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)