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5th EAGE St.Petersburg International Conference and Exhibition on Geosciences - Making the Most of the Earths Resources
- Conference date: 02 Apr 2012 - 05 Apr 2012
- Location: Saint Petersburg, Russia
- ISBN: 978-90-73834-23-1
- Published: 02 April 2012
41 - 60 of 178 results
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The Detalization of Difficult Constructed Objects on the Base of Seismic Processing Interpretation
By A.A. NikitinThe article deals with new seismic attributes and processing technologies that provide difficult constructed objects with the forecast of hydrocarbon identification.
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Complexing of the Reflected and Refracted Waves in the Processing and Interpretation of Multichannel Marine Seismic Data
More LessRefracted waves usually removed for processing and interpretation of the marine seismic data. However, they can provide additional information about the structure of the section and the presence of local low velocity zone. In this work the seismic section of the refracted waves along the profile 5-AR (East Siberian Sea) was constructed. With help the refracted and reflected waves was detected the low-velocity anomaly due to hydrocarbon deposit. Made refinement of the structure of the upper part of the lifting of Wrangel. Showed the advantage of using refracted waves for processing of the multichannel marine seismic data. Proposed to use the refracted wave in the processing and interpretation of marine seismic data. Showed the original method of determining the low-velocity anomalies, wich located in the sedimentary rocks.
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Advanced Modern Technologies for Old 3D Seismic Data Reprocessing - Case Study, Kharyaga Field
New seismic processing technologies can help extract additional useful information even if they are used with old seismic data. Seismic acquisition was performed in 2001 with the vibroseis and slanted NonWAZ acquisition system resulting in original bin size of 12.5x25m and nominal fold of 40. New advanced technologies were applied to get get better quality seismic imaging from full data reprocessing sequence. 5D seismic data regularization and interpolation to a denser shot and receiver grid were done to make possible the implementation of WAZ processing sequence. Data was, in fact, mapped to a new perfectly regular survey on bin grid 12.5x12.5m, which had higher fold of 160 and more regular offset and azimuth distribution. WAZ approach made possible COV- processing, azimuthal velocity analysis and 3D Radon using. The main features of our PSDM processing included separate PSDM runs for different azimuth sectors, PSDM from floating datum with shallow velocity derived from refraction statics model and using of non-linear hybrid tomography. Improvements in seismic data resolution, small magnitude faults imaging and correlation with well data are observed as the result of advanced technologies applying.
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Petroleum Systems in the Okhotsk Sea Region
More LessResearch targets are the largest basins of the Okhotsk Sea region (Northern and Western Sakhalin, Northern Okhotsk and Western Kamchatka). The data on composition, petrophysical and geochemical properties of borehole sections’ rocks, seismic survey (CDP technique) were analyzed. Particular attention was paid to the tectonic and sequence stratigraphic subdivision of covers, identifying sediment structure of petroleum systems and relationships between its components: oil source suits, reservoirs and cap rocks. Three groups of petroleum systems were distinguished: Upper Cretaceous, Lower Cenozoic (Pre-Upper-Oligocene) and Upper Cenozoic (Upper Oligocene-Pliocene). The Upper Cretaceous petroleum systems are the top of the folded (mostly destroyed) basement. The Lower Cenozoic petroleum systems are represented by the rift system with complex sediment structure and random pattern distribution of low permeable reservoirs. The Upper Cenozoic petroleum systems pose the highest petroleum potential. This petroleum systems are characterized by asymmetry associated with unilateral progradation of sequences towards deep-sea trenches. Reservoirs prevail in the proximal and central parts of the sequences; siliceous-argillaceous strata with high oil generation potential are predominated in the distal parts of the sequences.
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Making Seismic Data as CSEM Data through the Bäcklund Transform
Authors J.M. Virieux, R. Brossier, S. Garambois, S. Operto and A. RibodettiBäcklund transform is applied to a seismogram in order to construct a new signal where the time is transformed in a pseudo‐time the square of its dimension is expressed in seconds. The Bäcklund transform links partial differential equations related to wave propagation to partial differential equations related to diffusion. Potential applications have been performed previously from magnetotelluric data to pseudo‐seismic signals by using the inverse of the Bäcklund transform. This transform could be applied to the seismic signal through real computations. Therefore, we propose to transform seismic data into pseudo‐CSEM signals for possible applications of these diffusive signals as the initial stage of the full waveform inversion of seismic data.
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Quantitative Analysis of Seismic Uncertainty
Authors K. Osypov, D. Nichols, C.E. Yarman, F. Qiao, M. Woodward, N. Ivanova, Y. Yang, R. Bachrach and Y. LiuUncertainty is inherent in E&P business and understanding uncertainty enables mitigation of E&P risks. Therefore, quantification of uncertainty is essential in decision-making and managing uncertainty generates business value. One of the most critical parameters for reserves uncertainty and well placement is positioning of interpreted geological structure in the depth domain. Even with our best efforts to combine all available data there is still ambiguity in our models, caused by the inherent non-uniqueness of the seismic experiment. The result is uncertainty in the true positions of events in our images. These uncertainties can lead to exploration risk (e.g. trap failure), drilling risk (e.g. dry wells), and volumetric uncertainties. Whilst the underlying ambiguity can never be fully eradicated, a quantified measure of these uncertainties provides deeper understanding of the risks and leads to more informed decision making. We introduced a workflow for the statistical analysis of structural uncertainty associated with the ambiguity of tomographic velocity model building. Our method provides a quantitative way to determine the trap risk. Here we present this seismic-driven uncertainty analysis method and a case study for its application in the Gulf of Mexico.
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Geometric Analysis of Seismic Imaging Operators and Continuation Operators
By A.A. DuchkovIn this paper we provide an overview of some concepts and results by S.V.Goldin in the field of geometric theory of seismic imaging. Then we present some recent results on velocity continuation of seismic images developing his ideas. We will provide a few examples of Hamiltonians describing propagation of singularities during a velocity continuation of seismic (extended) images and propagation of isochrones in the framework of constant-offset migration.
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SVD for Macro-velocity Model Reconstruction by Full-waveform Inversion
Authors I. Silvestrov, D. Neklyudov and V.A. TcheverdaThe key element of seismic processing workflow in areas with complex geology is a depth velocity model building. A full-waveform inversion technique is considered currently both by academia and industry as a potential solution of the problem. The resolution and sensitivity of the method can be studied reliably by considering the Frechet derivative of the original nonlinear forward map. Examining its singular value decomposition provides the detailed information about the inverse problem, particularly about the low-frequency velocity model reconstruction ability. In the current work we present such study considering a look-ahead VSP experiment in which the velocity model below the borehole bottom is inverted. Using truncated SVD we show that success of the inversion strongly depends on the available low frequencies in the data and on the noise level. For the particular model we find the acceptable noise level and the required frequency content of the data needed for reliable inversion of the smooth velocity model. The presented approach may be adapted to any particular model and acquisition system and may be used as a tool for prediction the solution properties prior to any inversion procedure and for producing the requirements to the data which are necessary for successful inversion.
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Reliable Interval Q-factor Estimation from VSP Data
By E. BliasThe purpose of this paper is to present a new method for interval Q-factor estimate using near-offset VSP data. This method is based on objective function minimization of the difference between actual layered Q estimates and those calculated through interval Qs. To calculate interval Qs, we use Q estimates for all receiver pairs that provide reasonable Q values. To estimate layered Q between two receiver levels, we utilize an exponent approach which provides more accurate Q values than the spectral ratio method. Application of this method to real data demonstrates good correspondence between Q estimates and vertical velocity changes.
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Application of Perturbation Theory to TTI Media
Authors A. Stovas, T. Alkhalifah and P. GolikovUsing an elliptical tilted TI medium as a background we apply the perturbation method to compute both the eikonal and the slowness surface equations in a general TTI medium.
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Krauklis Wave - Half a Century After
Authors G. Goloshubin, V. Korneev, B. Kashtan, A. Bakulin, V. Troyan, G. Maximov, L. Molotkov, M. Frehner, S. Shapiro and R. ShigapovHalf a century after the original publication by Pavel Krauklis in 1962, the slow fluid wave in a fracture filled by fluid has got the name of its discoverer. This is the seventh personal name given to an elastic wave and which is now standing in a row with other remarkable scientists: Rayleigh, Love, Lamb, Stoneley, Scholte, Biot. The Krauklis wave is a slow dispersive wave mode that propagates in a fluid layer bounded by elastic media. There are indications that Krauklis wave plays a significant role in a variety of wave propagation phenomena in seismology, acoustics, engineering and hearing physiology. It is distinct by its large amplitudes, high dispersion and confinement to the fractures filled with fluid. In the prospecting seismology Krauklis wave might be an important component of the hydro-fracturing process, seismic wave propagation in fractured reservoirs, and fracture detection.
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Monitoring of Hydraulic Fractures Using Tube Waves in a Well Generated by Krauklis Wave Coming from Fracture Tips
By G.A. MaximovIn previous publications of the authors (Derov&Maximov, 2008, Maximov&al, 2011) the new active method for estimation of hydraulic fracture parameters was grounded. This approach is based on registration of the primary and the secondary tube waves in a well at incidence of external seismic wave on a well with fracture. The primary tube waves are generated when incident seismic wave intersect cross point of fracture and a well. The secondary tube waves are the result of interaction of Krauklis wave with a well. The Krauklis wave propagates along fluid filled fracture and is generated on fracture tips under action of incident seismic wave. The time delay between the primary and the secondary tube waves allows us to estimate the linear size of hydraulic fracture. The key question of this approach is amplitude of the secondary tube waves to detect them among other arrivals and noise. The developed mathematical model and numerical calculations represented in the report show that amplitudes of the secondary tube waves have the same order as amplitudes of the primary tube waves and hence they can be detected by VSP technique for both cases of subhorizontal and vertical hydraulic fractures for general 3D statement of the problem.
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A Frequency Dependent Ray Tracing for a Non-flat Boundary
Authors M. Protasov and K. OsypovThis paper presents an approach to ray propagation through a non flat boundaries. There is a fundamental problem in a ray based theory application in complex model that particularly contains complex boundaries. In many cases ray based theory breaks down (for example when boundary is rough with respect to wavelength) while physically there is wave propagation and it means actually there is ray propagation. But these rays are not high frequency rays actually these rays depends on frequency. The presented approach gives the way to compute frequency dependent rays within the ray propagation through boundaries. It is based on usage of boundary integrals. Outside the boundary it is a conventional ray tracing. The approach is applicable for ray based imaging and ray based tomography.
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Footprint of the Fine Structure of the Reservoir in Scattered Waves
Authors V. Cheverda, V. Khaidukov, V. Lisitsa, G. Reshetova, V. Pozdnyakov and V. ShilikovIn order to simulate interaction of seismic waves with cavernous/fractured reservoirs the finite-difference technique based on locally refined in time and space grids is used. The need to use these grids is due to essentially different scales of heterogeneities in the reference medium and in the reservoir. Parallel computations are organized on the base of 3D Domain Decomposition into elementary subdomains in the both reference medium (coarse grid) and reservoir (fine grid). Each elementary subdomain is assigned to its specific Processor Unit forming two groups – for reference medium and for reservoir. The data exchange between PU within the same group is performed in a standard manner – by nonblocking iSend/iReceive commands. The data exchange between two groups is done simultaneously with coupling of coarse and fine grids and is controlled by specially designated master PU. Results of numerical simulation for a realistic model of the carbonate reservoir are presented and discussed. On the base of numerical simulation an approach to recovery of orientation of fracture corridors is proposed and verified by comparison with direct observation of fractures within a well.
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Methodology for Evaluation of Fluid Saturation of Fractured Reservoirs on the Base of 3D Simulation of Seismic Waves
A detailed study of fractured reservoirs requires the use of all types of wave fields, as each of them displays its different properties the reflected waves are responsible for its correct positioning in space, while scattering ones bring information about its internal fine structure. Therefore, full description of the reservoir need an adaptive procedure for the construction of seismic wave images of different scales. It should be able to image not regular interfaces only, but microheterogeneities like caverns, cracks and fractures as well. In the paper we discuss some new approaches to scattered waves imaging on the base of accurate finite-difference simulation.
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Feasibility of Cross-well Hydrofracture Monitor by Accurate Numerical Simulation of Seismic Waves Propagation through Mu
Authors V.V. Lisitsa, C. Economides, G.V. Reshetova and V.A. TcheverdaIn this paper we present full scale numerical simulation of cross-well observations for shale gas exploration. The main technology used in production is based on hydro fracturing, however it is reported as a rule only about 20% of fluid used for fracturing gets back. Thus some fluid remains in the fractures blocking them from gas penetration. On the base of the full scale numerical simulation the principal ability to use time-lapse 3C cross-well observations in order to recover extremely fine variations of the background, including movement of watering zone was shown. Moreover strong diffraction was observed from the gas-water contact which allows to exploit intensively developed approaches of diffracted/scattered waves elimination and imaging to recognize the movement of the contact.
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Efficient Finite-difference Algorithm for Simulation of Seismic Waves in Models with Anisotropic Formations
Authors D.M. Vishnevsky, V.V. Lisitsa and V.A. TcheverdaAnisotropy is wide-spread in the Earth’s interior; however anisotropic formations typically comprise relatively small part of the models. It means that use of computationally expensive numerical algorithms for full anisotropy inside whole computational domain is rather inefficient. So, we present an original advanced finite-difference algorithm based on the domain decomposition technique with individual scheme, used inside subdomains. It means that in the main part of the model which is isotropic or VTI, a standard staggered grid scheme (SSGS) is utilized while the Lebedev anisotropy-oriented scheme is used inside domains with anisotropic formations. On the one hand this approach is as efficient and computationally cheap as SSGS. On the other hand it allows simulation of seismic wave propagation in arbitrary anisotropic formations.
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Layer-stripping with Offset Variable Parameters Compensating for the Reflected PS-waves Splitting in an Azimuthally Anisotropic Layer
Authors W.V. Karsten, E.V. Afonina and S.B. GorshkalevLayer-stripping algorithm with the offset variable parameters is applied to the synthetic data for the model with two different anisotropic layers. Layer-stripping with offset variable parameters and with constant parameters are compared. Variable parameters make it possible to compensate for the PSwave splitting in the upper anisotropic layer more correctly. Removing the influence of the upper anisotropic layer permits investigation the anisotropy of the lower layer
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New Prospects Discovery by Geological Support of Development Drilling
Authors A.G. Dubok, T.S. Zhuzhel, S.A. Potapenko and R.S. SharipovIn the current paper a successful example of solving a goal which took place over development drill support process is presented. The work was carried out using 3D seismic data reinterpretation (seismic facies analysis) and by operative involving of 8 drilled wells information into the model. Onshore oilfield X is located in Western Siberian region, productive formation is related to Upper Jurassic sistem and characterized by numerous uncertainties, including wide tuning zone, reservoir properties distribution. Data integration and effective drill support process allows to reduce uncertainty in J1 fm area of distribution, discover new perspective area to the following drilling. Additional oil reserves and high permeability of the formation are greatly increased drilling profitability.
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Correlation of Stratigraphic and Structural Framework of Begal Basin
Authors M. Jain and M. RastogiProlific hydrocarbon accumulations in eastern part of Bangladesh indicate the presence of active petroleum systems in the Bengal basin. Petroleum system analysis of the Bengal basin using available sand–shale percentage and organic carbon content, rock-eval pyrolysis and geological data help us to determine the probable Kitchen areas. Bakhrabad Gas Field being a well known gas field in the basin area, has been chosen for applying current methodology and then apply the same technique to an unknown Sariakandi-Madarganj area in the shelf-slope area. Detailed structural and seismo-stratigraphy of the Bengal basin have been established. Regional depth contour maps of different seismo-stratigraphic horizons of Madarganj-Sariakandi and Bakhrabad areas have been prepared to determine the sedimentary structures and spatial distribution of the stratigraphic units. In areas where there were no wells pseudo wells have been generated from those depth contour maps for the purpose of determining the kitchen areas. The analysis revealed presence of type I, II, and III kerogens. Petroleum systems analysis of Basin area (Greater Bakhrabad) and Shelf area (Madarganj-Sariakandi) areas revealed hydrocarbon generation, expulsion and potential of the Bengal basin and this may lead to new discoveries in future.
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