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- Volume 33, Issue 1, 2015
First Break - Volume 33, Issue 1, 2015
Volume 33, Issue 1, 2015
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Vibroseis source improvements towards broadband land acquisition
Authors Zhoulong Wei and Yuanzhou PanZhouhong Wei and Yuanzhou Pan demonstrate how to improve the amplitude through hydraulic and mechanical improvements and explore whether vibrator control electronics effectively supress harmonic distortion at low frequencies. Increased seismic frequency bandwidth towards both low and high frequencies can improve image resolution, reservoir characterization and quantitative seismic interpretation. However, using the vibroseis method to acquire broadband seismic data is very challenging in land data acqusition. At low frequencies, due to mechnical and hydraulic limitations, such as limited reaction mass stroke, the pump flow and harmonics, it is very difficult for a seismic vibrator to produce sufficient ground force at fundamental frequencies. At high frequencies, due to low rigidity of the vibrator baseplate resulting in poor coupling, it is also difficult for the vibrator to efficiently radiate the ground force into deep ground. Often, the high-frequency force energy produced by the hydraulic system is wasted in bending the baseplate. Therefore, the first challenge in broadband vibroseis data acqusition is to improve the vibrator performance so that the vibrator can produce sufficient force with a good S/N ratio in a wide frequency bandwidth.
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Land seismic in difficult terrain and complex geology: a case study from the Jungar Basin, northwest China
Authors Huantong Lv, Xianmin Li, Zaichao Jiang, Long Zhang, Lixin Xiao, Jian Wu, Yan Liang, Bo Liang, Meng Zhang, Rong Li, Fang Li, Sherman Yang, Peter van Baaren, Thomas Heesom and Hongping XiaoHuantong Lv, Xianmin Li, Zaichao Jiang, Long Zhang, Lixin Xiao, Jian Wu, Yan Liang, Bo Liang, Meng Zhang, Rong Li, Fang Li, Sherman Yang, Peter van Baaren, Thomas Heesom and Hongping Xiao describe how a high-density, point-source, point-receiver approach can address statics and noise challenges of rough mountain thrust-zone topography and deliver high-quality imaging results. High-density, single-component, point-receiver land acquisition geometries are increasingly displacing ‘conventional’ acquisition designs that are based on long-standing practices of sparse sampling, low channel counts and an analog approach to noise attenuation via multi-sensor arrays. Over the past decade, dense point-receiver – often complemented by point vibroseis or dynamite source – geometries have been proven in diverse locations including Australia, the Middle East, North and South America, Russia and China. Two case histories from China have recently been published that demonstrate the success of the approach in solving geological challenges encountered in the exploration and development phases of challenging oilfield environments in the Sichuan Basin (Xiao et al., 2014) and the Ordos Basin (Wang et al., 2014).
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Vibroseis equipment for efficient low-frequency generation and high-productivity operations
Authors Nicolas Tellier, Gilles Ollivrin and Daniel BoucardNicolas Tellier, Gilles Ollivrin and Daniel Boucard present the implications of generating low frequencies for productivity and equipment capability and discuss how modern vibroseis solutions address this challenge. Extending the recorded seismic bandwidth has become an increasingly prevalent trend in the industry, for the clear benefits this approach provides for seismic imaging: reflections with reduced sidelobes, improved vertical resolution, more accurate velocity models and inversion providing better reservoir characterization.
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Access and exploration opportunities – A view of the potential in frontier and mature basins
By Brian HornBrian Horn demonstrates an overview of hydrocarbon prospectivity in six regions – East Africa, Equatorial South America, Southern Brazil, Uruguay, Argentina, and the Gulf of Mexico. The continued search for commercial accumulations of hydrocarbons has often led geoscientists to believe that the remaining future potential for exploration in frontier and mature basins is diminishing with time. However, a brief overview of frontier, emerging, and mature basins around the world would suggest that several opportunities still remain. In 1952, Wallace Pratt summarized this pessimistic view of individuals and companies in the E&P industry noting, ‘We have persistently underestimated the amount of oil and gas that have been stored up in the Earth’s crust.’ A brief overview of six regions (East Africa, Equatorial South America, Southern Brazil, Uruguay, Argentina, and the Gulf of Mexico) where the exploration activity ranges from frontier to mature suggests there is compelling evidence for optimism and future success.
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Is the GeoChron Model the way forward for mathematical sedimentary geology?
Jef Caers of Stanford University reviews Elements of Mathematical Sedimentary Geology: the GeoChron Model by Jean-Laurent Mallet and published by EAGE. Anyone involved in subsurface forecasting will be aware of the impact that the zeroth order structural framework has on assessing reserves and reservoir performance. Yet, until 2004 (Mallet, 2004), no single unifying mathematical theory existed to create such a structural framework within which reservoir properties can be generated consistently. Most existing techniques borrowed ideas from CAD techniques in fields not related to geology, employing ad-hoc meshing and gridding that result in structural models and grids that were geologically implausible, requiring tedious correction or worse and also requiring simplification by removing faults and horizons too complex to handle. The initial 2004 paper has now evolved in to a new book and new commercial software-the culmination of Jean-Laurent’s brilliant career in this field.
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High-fidelity adaptive curvelet domain primary-multiple separation
Authors Xiang Wu and Barry HungIn this paper, we propose an adaptive scheme for primary-multiple separation whereby the multiples are first estimated from the seismic data and then removed using the curvelet transform. Because of the sparseness of seismic data in the curvelet domain, the primary-multiple separation problem is formulated by incorporating L1- and L2-norms, based on the framework of the Bayesian Probability Maximization theory. An iterative soft-thresholding method is used for solving the optimization problem. Prior to removal, the predicted multiples are preconditioned to match the actual multiples in the seismic data by least-squares matched filtering. We show that such an adaptive implementation is more robust and has a superior performance to the conventional least-squares method for attenuating multiples. To improve the effectiveness of primary-multiple separation for complex data, we develop a frequency-regularized adaptive curvelet domain separation approach. The method is optimized for different frequencies to improve attenuation in the presence of noise and in areas where multiple models are less accurate (e.g. narrowing of frequency bandwidth due to the convolution process in SRME). Accordingly, this extension provides more flexibility and leads to higher separation fidelity than its original form. We demonstrate the application of our approach on synthetic and field data. The results obtained from our approaches show significant improvement over those obtained from conventional least-squares methods.
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Impacts of surface fluxes on inter-seasonal heat storage in soils
More LessThis paper presents a brief review on the classification and national and international initiatives regarding inter-seasonal heat storage devices. A three-dimensional numerical model that simulates a field-scale case study, coupling both soil mass and storage system behaviour, is presented and applied to study the dependence of these systems on the correct description of heat transfer interactions between the soil and the atmosphere. With this aim three different approaches are used to describe heat transfer coefficients at the soil surface. The results show that an accurate description of the thermal energy processes at the soil surface is key to correctly assessing the performance of heat storage systems in soils.
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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)