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4th EAGE St.Petersburg International Conference and Exhibition on Geosciences - New Discoveries through Integration of Geosciences
- Conference date: 05 Apr 2010 - 08 Apr 2010
- Location: Saint Petersburg, Russia
- ISBN: 978-90-73781-79-5
- Published: 04 May 2010
61 - 80 of 210 results
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Modeling Fluid Flow under Sonic Wave Field in Fractured Porus Media–With an Approach to Capillary Forces
Authors I. Najafi, M. Ghazanfari, C. Ghotbi and R. KharratTill now, no mathematical model is presented to model the flow under sonic field be applied in fractured reservoirs. This will be more noticeable when we bear in mind that several reservoirs in Middle East region are fractured. In this work the effects of elastic waves on capillary trapping and mobility of Bingham plastic fluids in fractures have been investigated. Eventually, a model for predicting the influence range of the wave in fractured reservoirs is presented. The results of this study clarified that radiation of wave with low frequency and intensity extremely increases the flow rate and decreases the minimum pressure gradient required for flow of Bingham plastic fluids in fractured porous media. In addition, the fractional flow of Bingham plastic fluid is increased dramatically. Further, it is shown that the effect of elastic wave is of less importance in higher pressure gradients. Finally, according to this mathematical study, it has been observed that this technology would not be applicable in high pressure fractured reservoirs.
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Field X Prospective Zone Identification Based on Conducted Investigations and Level of Geological Knowledge
Authors D.V. Romanov, T.A. Pospelova, O.M. Grechneva and E.V. KosourovaIn given article the approach of zone identification by the example of Field X is discussed. The criteria used in this method are the following: level of geological knowledge, initial data quality, character of fluid saturation, sedimentological features of productive formations, facial distribution and extension, net pay thickness, compartmentalization of pay zones, position of fluid contacts. On this basis 3 zones of different prospectivity and level of knowledge have been identified in Field X. This subdivision is of interest from the standpoint of further field investigation program planning, new exploration and exploitation wells location, optimal development methods choice and identification of stages of field bringing into development. Acquisition of new information and production data during the process of further field research and development will allow specifying and correcting given scheme of zonin
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Elastic Properties of Source Rocks
By R. AhmadovUnderstanding how to relate the nanometer-scale phenomena and properties of source rocks and to their complex macroscopic properties is one of the current challenges in rock physics. This study shows a combined application of SEM, CLSM imaging and nanoindentation characterization, which provides the microscopic basis to analyze these macroscopically complex and heterogeneous rock samples. Organic matter was successfully imaged within the matrix of the Bazhenov Formation despite inherent lithologic differences of the phases. Nanoindentation measurements showed kerogen within the Bazhenov Formation to be softer than the surrounding mineral matrix. In particular, the Young’s modulus of kerogen from the Bazhenov Formation varies between 10 and 15 GPa, whereas bulk and shear moduli vary from 5 to 10 GPa and from 4 to 5 GPa, respectively. At different Poisson’s ratios, corresponding elastic properties measured and computed in this study and by others are in good agreement.
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Effect of Acoustic Stimulation on Petrophisical Properties of Oil Reservoirs–Laboratory Tests
More LessWe made original laboratory experimens for fluid flows through porous media by acoustic stimulation. New results were obtained to increase of oil production.
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Generalization of the Biot’s Equations for Account of Fluid Shear Relaxation
By G.A. MaximovProperties of heavy-oil reservoirs show rheological behavior and their correct description in porous medium is important for optimization of recovery methods. Account of viscosity relaxation is usually introduced through generalization of the Biot’s operator for dissipation function. But this approach is not completely consistent because it doesn't take into account additional degree of freedom dealt with shear motion of viscous fluid which is omitted in the variational principle being the initial basis of Biot’s theory . Based on the generalized variational principle Maximov (2006a, 2006b) the system of the generalized Biot’s equations is derived for consistent account of fluid shear relaxation. Account of shear viscosity relaxation leads to existence of a couple shear propagation modes additionally to a couple of longitudinal modes as in the Biot’s approach. At this the one shear mode is an acoustical one, while the other shear mode has diffusive behavior at low frequencies. Phase velocity and attenuation factor for the second shear mode linearly depend on frequency in the low frequency limit that is different from analogous behavior of diffusive longitudinal mode with the root frequency behavior of analogous values.
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Accurate Lithology and Porosity Prediction using Simultaneous Angle Stack Inversion on the Shtokman Field
Authors I.V. Yakovlev, A. Barkov, Y. Ampilov, K. Filippova, A. Radchenko and I. YagovStudying the Shtokman field which is unique both in terms of its estimated reserves and quality of its gas bearing reservoirs leads to a number of specific geological problems. Accurate prediction of reservoir properties from seismic data is interfered here by extremely high values of gas saturation imprinting all dynamic parameters of seismic record. This makes lithological classification of a section and evaluation of reservoir properties quite tricky. Solution of the problem can be delivered with the use of simultaneous angle stack inversion which allows to recover from seismic data a set of independent elastic parameters providing a multi-dimensional domain for further detailed lithology analysis. After that it is possible to accurately evaluate reservoir properties for each litho-type.
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AVO Inversion–A Suitable Tool for Seismic Reservoir Characterization in the Ancient Reservoirs of the Baltic Syneclise
Authors S. Klarner, O. Zabrodotskaya, J. Zielinska-Pikulska and E. Nowak-KoszlaIn the Polish sector of the Baltic Sea, Middle Cambrian sandstones are the main hydrocarbon bearing reservoir. The sandstones are several tens of meters thick, and due to their age, they are thoroughly compacted and may exhibit average porosities in the range of 10-12%. However, there are also areas with significantly lower porosities. The aim of the work was to investigate whether AVO inversion of the seismic data may help to map reservoir trends and properties. Albeit their age and associated with that, relatively low porosities and high velocities, the investigated sandstones show an AVO behavior typical of very clean quartz sandstones which clearly separates them from the overlying Ordovician marly limestones. The observed extremely low Vp/Vs ratios can be utilized for the identification of reservoir sweet spots and hence may help to reduce the further exploration risk.
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The use of Partial Stack Inversion for the Purpose of Prediction and Delineation of Reservoir Areal Extents at the Sakha
Authors I.A. Babenko, T.V. Nekrasova, S.L. Fedotov, E.O. Malysheva, G.G. Voikov and O.S. Zhukova O.S.The paper describes the use of partial stack inversion (RockTrace) for the purpose of prediction and delineation of gas-saturated reservoir areal extents at the Sakhalin shelf
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Post-stack and Pre-stack Seismic Inversion Workflow in Frequency Domain
More LessA new post-stack and pre-stack seismic inversion workflow in frequency domain is proposed. The technique is based on Wiener inversion theory and Tikhonov regularization approach for calculation in frequency domain. Pre-stack inversion is based on Zoeppritz and Aki-Richards equations. The workflow built like plug-in to regular seismic workstation environment (Petrel). The post-stack and pre-stack seismic inversion technique is demonstrated on a controlled synthetic example and on a real seismic study case. Предлагается новая технология сейсмической инверсии в спектральной области для полных и частичных угловых сумм (AVO инверсия). Технология базируется на теории оптимальных фильтров Винера и теории регуляризации А.Н. Тихонова для стабильного обращения оператора свертки в спектральной области. Для инверсии по частичным угловым суммам (AVO инверсия) использован итерационный расчет на основе точных уравнений Цеппритца и приближенных формул Аки-Ричардса. Технология реализована в виде плагинов для программного комплекса Petrel. Приводится результаты опробования технологии на модельных и практических примерах.
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Dip Extraction from Three–dimensional Depth Images–Algorithms and Applications
By T.J. MoserThe estimation of the slope of locally planar events in a seismic section has become a popular tool with many applications. In the time domain, locally planar events are estimated by considering them as plane wave solutions which satisfy the wave equation, and the time variable plays a special role. By contrast, in depth image domain there is no time variable and, strictly speaking, no wave equation or plane wave, but instead a reflectivity image which may be locally planar. The reflectivity image in depth depends on three spatial coordinates which are fully interchangeable, and dips may cover the full 360 degree angle range, including vertical and overhanging dips. Dip extraction on three-dimensional images can be conveniently carried out by a least-squares fitting of derivatives in the neighborhood of each image grid point. This allows recovery of dips of any orientation, including vertical ones. Multivariate B-spline representation of the image enables efficient inter- and extrapolation at any location together with efficient evaluation of the necessary derivatives.
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Next-Order Static Correction
Authors A.V. Masjukov, V.V. Masjukov and I.S. MurzovWe propose a theory of static correction that accounts for slopes of seismic events in the first-order accuracy. The theory results in spatial shifts of shots and geophones that can be found jointly with usual static time shifts. Involving the additional degree of freedom improves removal of near-surface effects in seismic data. The theory is verified in a synthetic test.
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3D De-multiple over Shtokman–A Case Study
Authors B. Webb, A. Sazykin, T. Grechishnikova, A. Barkov and I. YakovlevIn this case study we discuss parameterisation considerations for General Surface Multiple Prediction of complex 3D multiples on the Shtokman field in the Russian sector of the Barents Sea. The multiples in this area are very complex even though the water bottom is fairly simple. Nevertheless small irregularities in the sea bed create some multiple diffractions. Because of their 3D nature, it is not possible to predict and remove multiple diffractions using 2D de-multiple techniques as the multiple ray-paths lie outside the plane of acquisition in the sail-line direction. The multiple prediction was performed using a new approach to 3D SRME ‘3D General Surface Multiple Prediction’ (3DGSMP) described by Moore and Dragoset (2008). This enabled up to generate a more accurate multiple model which helped attenuating the multiples much better than what we had seen with 2D assumptions. In this paper we will firstly present the Shtokman field, we will then discuss why the 2D SRME approach has not managed to attenuate very effectively the multiples and follow with a discussion on the parameterisation of the 3D GSMP for the multiple prediction where we compare 3D GSMP with 2D SRME.
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Short-period Static Correction Without NMO
Authors A.V. Masjukov, I.S. Murzov and V.I. ShlyonkinWe propose a robust method for residual short-period static correction based on the aligning of seismic events in a moving gate. It is not presumed that data can be stacked with a hyperbolic move-out. The method is verified in real-data examples.
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Prestack Depth Migration and Velocity Model Derived from First Break Tomography at Long Offsets
Authors Y.V. Roslov and V.V. PolovkovFirst break tomography at long offsets is used to build up velocity model for prestack depth migration. Processing of refracted and diving waves forming first breaks allows obtaining of velocity information in complex geological structures where reflection seismic fails. That, first of all, concern cases of smooth velocity anomalies which are not related with horizons. The advantage of the approach proposed is demonstrated at test models and Pechora Sea survey where multichannel seismic data and wide angle profiling data were acquired independently along one line. Velocity model derived from first break tomography of wide angle data was used for multichannel data prestack depth migration. The final seismic image is compared with ones obtained with standard algorithms)
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Poststack Time Migration Velocity Analysis by CRS Diffraction Stacking
Authors S. Dell and D. GajewskiThe Common Reflection Surface stack provides the stacked section as well as kinematic wavefield attributes. We demonstrate on synthetic examples, how this attributes can be used to effectively separate reflected and diffracted energy. After separating the diffracted wavefield we introduce a technique for poststack time migration velocity analysis. Due to the application in the poststack data domain the presented procedure is stable and fast producing highly focused time migrated images.
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Velocity Analysis for the Faroese GlyVeST Data–Merits of Multiple Attenuation – 3D Visualization and CRS Processing
Authors K.D. Nguyen and R.J. BrownVelocity analysis is one of the most important and critical aspects of seismic processing. It involves picking of optimal velocity functions on a predefined analysis grid, which is a time-consuming and laborious task. Whilst velocity picking is quite simple in principle, implementation proves to be a great deal more complicated, for numerous reasons, such as: the presence of multiples, poor signal-to-noise ratios, limited offset ranges, etc. Due to these difficulties, velocity analysis remains the phase in which the most human intervention occurs. A great deal of effort has been devoted toward reducing the time spent and increasing the accuracy of this crucial stage, either by better conditioning of the data for velocity analysis or through the development of highly interactive graphics software to aid in velocity picking. In this paper, we highlight the merits of multiple attenuation and 3D visualization, as well as common-reflection-surface processing, to the velocity analysis of the GlyVeST seismic data. A good multiple-attenuation scheme conditions the data for velocity analysis, while 3D visualization helps to provide better facilities for velocity picking and speed up this laborious task. Finally, common-reflection-surface processing overcomes the problems of limited offset range and poor signal-to-noise ratio, characteristic of the GlyVeST data.
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The Obtaining of Images of Geological Environment Based on the Diffraction Transformations of the Common Offset Gather
Authors V.I. Bondarev, S.M. Krylatkov and I.A. KurashovThe given paper describes the original algorithm of obtaining the seismic images of geological environment based on the diffraction transformation of wave fields of common offset gather. Also there is adduced the operator of such a transformation in the time domain. The examples of testing the transformation on the synthetic seismograms are shown. And there are demonstrated the results of testing the transforming algorithm on the experimental data. The shown time sections are obtained with help of the new technology represent the new original images of the geological environment. The analysis of these images can be particularly useful for studying the complicated structure of geological environments. The new technology of the diffraction transformation of seismic wave fields gives a whole range of different images of environment, including those on which either mirror or scattering components of the wave fields are emphasized.
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Possibilities of Application of Multiwave Seismic Prospecting for an Estimation of Elastic-deformation Modules of a Meth
Authors D.P. Zemtsova and A.G. PogosyanOn the basis of laboratory researches of physic-mechanical properties of coals and containing rocks in Kuzbas, quantitative parities of change of elastic properties of coals against containing rocks are established. Efficiency of a quantitative estimation of elastic-deformation properties of environment is proved at studying of physical properties of coals on the basis of the data multiwave boreholes seismic prospecting. The technology, allowed to reveal issue activity of the environment caused internal gas-dynamic is tested by processes.
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New Seismic Technologies for Tight Gas Exploration and Development
Authors A. Araman and P. MazumdarRulison Field is a basin-centered gas accumulation located in the Piceance Basin of northwest Colorado. The reservoir consists of lenticular fluvial sands, shales, and coals of the Upper Cretaceous Williams Fork Formation. Typical sand body thicknesses are 10-15 ft, an order of magnitude lower than the seismic resolution which is 105 ft. The sandstone reservoirs are the primary target and are typically low porosities (6-12%) and very low permeabilities (1-10 µD). The best production is dependent on the fracture permeability. The major objectives of the reservoir characterization in Rulison are (1) the imaging of the lenticular sand bodies, (2) the identification of the high quality overpressured productive sandstones, and (3) the determination of the fractured intervals. In order to achieve these goals, a quantification of anisotropy in the reservoir is essential in understanding the seismic amplitude responses. Elastic anisotropic AVO modeling and anisotropic velocity model building are the tools required for (1) the inversion of converted shear-wave surface seismic data and (2) depth imaging of the sand bodies based on non-converted shear-wave VSP data.
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