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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
51 - 100 of 210 results
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Horizontal Well Electric Logging Data Interpretation on the Basis of Direct and Inverse Problem Solving
By A.P. PotapovEstimation of drilling pipes impact on electric logging data provided by “AMK Gorizont” tool was made on the basis of mathematic modeling. An algorithm of specific electric resistance determination is described on the basis of mathematic measurement modeling for the specified model (sonde, environment) and solving of an inverse problem. Advantages of the algorithm for the interpretation of actual logging data are shown.
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Casing Technical State Control of Oil and Gas Wells by Integrated Russian–China Equipment
Authors A.A. Miller, A.V. Miller, S.V. Stepanov, V.G. Sudnichnikov, Q.I. Fu, J. Luo and K. Lin’Due to common efforts of Russian and Chinese specialists an integrated apparatus DDS73F-EMD was designed, which contains modules of multilevel borehole geometry tool and electromagnetic defectoscopy. The tool allows making a detail survey of casing technical state in one round trip, which is important for effective planning of well-workover operations. The detailed image of column inner surface is reconstructed according to the borehole geometry tool data in scanning and 3D image, which is linked to the apsidal plane. Herewith corrosion intervals, holes and pits on casing inner surface as well as buckling zones are fixed. Due to the defectoscope module data corrosion, fractures of any directions, defects of the second from the well axis casing are identified, wall thickness of the inner and the second column on inner and outer column surface is determined. Joint consideration of the result achieved by two different in basic physics methods essentially improves accuracy and definiteness of the interpretation.
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Assessment of Clustering Methods for Predicting Permeability in a Heterogeneous Carbonate Reservoir
Authors F. Khoshbakht and M. MohammadniaPermeability, the ability of rocks to flow hydrocarbons is directly determinedfrom core. Due to high cost associated with coring, many techniques suggested to predict permeability from easy to obtain and frequent properties of reservoir such as porosity. This study launched to put clustering methods (MRGC, SOM, DC and AHC) into practice in permeability prediction of a heterogeneous carbonate reservoir in SW Iran. Conventional approaches like empirical models and regression analysis were also examined. Performance of all examined methods compared in order to choose the best approach for predicting permeability in uncored wells of the studied field. For all clustering methods, selecting optimal number of clusters is the most important task. The optimal value for the number of clusters selected by iteration. The optimal number of clusters for MRGC, SOM, DC and AHC is 7, 9, 9 and 8 respectively. Empirical equations and regression analysis could not predict permeability well and R2 of estimation of both approach were around 0.6. Generally performance of clustering techniques was acceptable regarding to Fahliyan formation. These techniques predict permeability between 1 and 1000 mD very well and just overestimate permeability below 1 mD. SOM performed the best between examined techniques (R2=0.7911).
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New Tool and Programming and Methodological Software of Geophysical Propagation in Well
Authors I.N. Eltsov, M.I. Epov, K.N. Kayurov, A.N. Petrov, C.V. Suhorukova, A.Y. Sobolev and A.A. VlasovTraditional task as a identification boundary of beds, definition of lithology and the estimation of oil saturation can be solved by new logging tool SKL. In advantage fresh tasks as estimation of the dielectric conductivity and it dispersion in frequency range of HILS can be solved by this tool also. Identification of invaded zone can be made by only one tool combined two different tools – LL & HILS. The example of real LL and HILS logs is applied. Effective interpretive system EMF-Pro is designed to processing SKL logs
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Frequency Dispersion of Electrical Permittivity from Lateral Logging and High–frequency Induction Logging Data
Authors C.V. Suhorukova and M.I. EpovMismatching in apparent resistivity processing from lateral logging and high-frequency induction logging data on clayey intervals is able to explain for a frequency dispersion of dielectric permittivity. The value of relative dielectric constant from 875 kHz to 14 MHz frequency range can be estimated by the complex interpretation data of LL and HILS. Results obtained by this method matching with data, measuring on clay pattern obtained by outside research group
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Cement Bond Gamma Logging Data Algorithmic Interpreting
Authors D.A. Kozhevnikov and I.S. DeshenenkovProblems of cement bond gamma logging interpretative metrological control are considered. Methods for the detection of various cementing defects cases are proposed. Appropriate models are presented. Automated algorithm for quantitative cement bond gamma logging data processing and interpreting as well as its results are introduced.
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Development of Formation Evaluation Methods for Structurally Complicated Carbonate Reservoirs
Authors A.V. Chashkov and V.M. KiselevAuthors of the work considered the ability of lithologic structure determination and total and secondary porosity defining on the basis of one of the several oilfields located in the Eastern Siberia. This oilfield is characterized by chemical and biogenic reservoir rocks with porosity of cavity and fractured structure. There are some theoretical backgrounds for porosity structure determination by comparing data of sonic log with formation evaluation methods using for total porosity interpretation. However fracture and cavity influence on porosity determination can be hided by various petrophysical parameters such as shaliness, salinization, anhydritization etc. In the given work the technique by a quantitative estimation of porosity of fractures, vugs and intergrain porosity for carbonate reservoirs with difficult lithological structure on complex sonic logging- neutron gamma-ray logging is offered. For the correct decision of the assigned task it is necessary to make "adjustment" of the stated algorithm for those wells where full formation evaluation methods was executed.It is showed that using given method obtained results reliably represent geological features of considered field.
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System–defined Geological Modeling of a Deposit Treated as an Integral
By S.I. BilibinThere are pointed out the problems in geological modeling of oil and gas deposits, arising during synthesis of particular stratum digital models into a single integrated model. It is shown, that only a system approach to the initial information, including concept development for stratum formation history and deposit accumulation, brings a possibility to build a whole deposit model consistent with geological principles. It is also shown, that the differentiated approach to various modeling objects allows one to build a 3D geologic model adequate to the initial data, which provide increase in reserve estimation reliability. There are given examples, when the integrated object structure revision has allowed the creation of non-contradictive geologic model.
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The Complex Method of Geological Modeling of Fractured Carbonate Reservoir by the Example of Hasyreyskoye field
Authors Y.V. Merkushkina, K.S. Savichev and D.N. LevinIn this work present the method of geological modeling of fractured carbonate reservoirs by the example of Hasyreyskoye field in Timan-Pechora basin. This type of reservoirs has two components of the pore space – matrix and fractures. Two methods were be used for creating this geological model of the reservoir. Modeling of the matrix part include the sequence stratigraphy method of study the geological section using the core and well data. The sequence stratigraphy method has allowed more precise relationship between porosity and permability by the facies. The modeling of discrete fracture network was be used for creating of fractured part of reservoir. Seismic and well data (FMI) were be used for modeling of fractures. As result both created models were be integrated in the united fluid-flow model for making technological decisions. Represented method may be recommended for modeling of such type of reservoirs with the object of accurate definition of subsurface geology and optimization of exploitation system
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Examples of Multidisciplinary Approach Application for Fractured Reservoirs of West and East Siberia
By O.V. PinousTwo methods of fracture modeling are reviewed using two examples from West and East Siberia. These include CFM (Continuous Fracture Modeling) and DFN (Discrete Fracture modeling). Practical utilities of these techniques have been examined for the Siberian fractured objects.
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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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Generalization of the Vertically Heterogeneous Velocity Models
By A. StovasI propose a power-gradient velocity model which incorporates several well-known velocity models as special cases. The proposed velocity model covers wide range of possible velocity distributions and has four parameters, which gives more flexibility in velocity-model manipulation. For the proposed non-linear velocity model, I compute the kinematical characteristics: offset-traveltime parameteric equations, traveltime parameters, relative geometrical spreading and the phase of the propagator. The kinematical characteristics are investigated with respect to a parameter responsible for non-linearity of velocity distribution. The inversion of traveltime parameters is discussed in three- and four-parameter framework.
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Optimum Technique of Seismic Prospecting of a Method by the Reflected Waves
By A.N. TeleginIs considered a choice of optimum parameters of a technique of seismic prospecting by a method of the reflected waves of the received results directed on unequivocal geological interpretation. In particular communication of a kind of shooting (digitization of results on the area of works) with complexity of a relief of geological borders, and parameters seismograms CMP (fold of supervision and offset a source-receiver), received in each bin, with complexity of a registered wave picture is defined. Formulas for calculation of concrete parameters of a technique of works are resulted.
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Digital Accelerometers – Expectations and Practical Achievements
Authors D. Mougenot and A.V. CherepovskiDigital accelerometers, a new generation of seismic sensors, were developed at the very end of 20th century and were intensively tested by seismic contractors and oil-and-gas companies at the dawn of 21st century. These 1C or 3C MEMS-based accelerometers integrated with electronics are to deliver a well-calibrated digital signal. Contrary to arrays of geophones, they must be recorded individually as point receivers. Since noise is only filtered during processing, the interval between point receivers must be reduced to avoid spatial aliasing of the noise and to ensure high fold. The benefits provided by digital sensors are both operational (weight, power consumption, integration with the line…) and geophysical (amplitude & phase response, vector fidelity, tilt detection). Early 2D-3C tests as well as current 3D production surveys, including those performed by the highest channel count crews (35,000+), confirm the benefits of these new sensors: immunity to pick-up noise due to full digital transmission; increase of the frequency bandwidth of the signal and of the associated vertical resolution; well-calibrated amplitudes suitable for AVO and inversion. Case histories are collected to illustrate the improved seismic imaging and reservoir characterization provided by the digital accelerometers.
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Geophysical Benefits of an Improved Seismic Vibrator
More LessTest results of a modified seismic Vibrator are shown that improves the signal at both lower and higher frequencies, results in better prediction of harmonic energy and a more accurate and consistent Ground Force Estimate
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Enhanced Resolution–Imaging and Interpretability Resulting from Dual–sensor Towed Streamer Acquisition
Authors S.J. Pharez, M. Farouki and A. LongEvery reflection wavelet recorded by a marine streamer is accompanied by a ‘ghost’ reflection from the sea surface. If both the seismic pressure wavefield and the vertical component of the particle velocity can be acquired using co-located pressure and velocity sensors, it is then possible to combine these datasets to produce a seismic image with the receiver ghost removed. The dual-sensor streamer has been developed to record both of these desired seismic wavefields and enable extraction of the up-going and down-going pressure and velocity wavefields. The up-going pressure wavefield represents the de-ghosted pressure result. The dual-sensor streamer architecture uses densely sampled co-located pressure and velocity sensors housed in a low-noise ruggedized solid streamer to deliver de-ghosted data in one pass, using one streamer depth. Deep streamer towing facilitated by the technology increases the operational weather window, reduces noise, and increases signal penetration. The de-ghosted seismic data exhibit greater frequency bandwidth and greater signal-to-noise ratio. The dual-sensor streamer enhances resolution and imaging of the subsurface and through more responsive data processing and improved seismic inversion, contributes to a better understanding and interpretability of any asset.
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Experience in the Study of Engineering Geocriological Conditions under Shallow Waters at the Yamal Peninsula
Authors M.R. Sadurtdinov, A.M. Tsarev, V.A. Dubrovin and A.G. SkvortsovThe results of seismic surveys held at the geocryological stations Marre-Sale (western Yamal, the summer of 2009). The engineering and permafrost conditions under shallow river and lake are studied. Analysis of the field structure of compression and share SH-waves is completed. It is shown that share refracted SH-waves should be used for displaying the configuration of permafrost table which lay at 5-6 m depth. The salinity of frozen soils could be assessed also using this type of seismic waves
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Application of New Seismic Ocean Bottom Technology in Deep Water in the Middle Caspian Sea
Authors G.P. Vartanov, S.Y. Shtun, C. Walker and D.G. BaturinIn December 2008, CKNG commissioned Reservoir Exploration Technology (RXT) to acquire an Ocean Bottom Cable (OBC) 3D seismic survey over the Centralnaya field in the Middle Caspian Sea. The survey, which is in an area with water depths ranging from 400 to 600 meters, was acquired using the VectorSeis Ocean (VSO) OBC system, operated exclusively by RXT. This is the first time this technology has been employed for Russian client. 4C data acquisition offers a great potential for further studies of the Centralnaya field geological features using additional information contained by converted and share wave data. The acquired 3D4C survey represents unique data base for further exploration, development and production planning of the Centralnaya field
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Comparison of Physical Modeling of Elastic Wave Propagation in Porous Fractured Medium with Theoretical Models
Authors V.E. Rok, N.A. Karaev, S.M. Glubokovskikh and E.O. ManutcharyantsExperimental data for ultrasonic waves propagation through inhomogeneous medium modelling porous fractured rocks is compared with calculations based on Hudson's Theory and Differential Effective Medium (DEM) Method for elastic moduli and sonic velocities.
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Numerical Simulation of Seismic Waves' Propgation in Multiscale Media
Authors G.V. Reshetova, V.V. Lisitsa, V.A. Tcheverda and P. ThoreNew numerical method for large-scale computer simulation of seismic waves in multiscale heterogeneous media is developed. As multiscale hereafter we mean media with heterogeneities of extremely different sizes. In the paper we deal with a layered medium containing one layer with water filled microheterogeneitis of subseismic scale (less than 0.01 of dominant wavelength). In order to be able to describe these heterogeneities reliably locally refined staggered grid is used and corresponding finite-difference technique developed and implemented. Its stability is studied and intensity of artificial reflections estimated. On this base numerical simulation is performed and structure of scattered waves analyzed in dependence of porosity and geometry of microheterogeneities.
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Physical Modeling Supports Testing of Seismic Techniques for Porous–fractured Reservoir Characterization
Authors N.A. Karaev, E.A. Kozlov, G.N. Karaev, Y.P. Lukashin, O.M. Prokator and B.M. SemenovThe possibility of detecting azimuthally aligned fractures and estimating fracture density, orientation and saturation type is investigated by measuring ultrasonic offset-and-azimuth-dependent reflection and transmission amplitudes of elastic waves in a large (160x160x30cm) physical model. The model is represented by three layers of Plexiglas, with the middle layer consisting of four or five replaceable fragments of “reservoir rock” with controlled matrix (“equant”) porosity penetrated by plane, rough face, azimuthally aligned fractures of controlled density and opening. The pores and fractures are hydraulically connected and filled with a replaceable fluid; then controlled uniaxial stress is applied. On the whole, the model imitates the East Siberia carbonate fractured reservoir. The 2D observations with diverse acquisition parameters imitated at the model surface have shown that (a) the most reliable information on the fracture localization and parameters is provided by converted P-S waves; (b) fracture-induced azimuthal anisotropy of P-P waves attenuation exceeds azimuthal anisotropy of the P-P velocity by an order of magnitude; (c) fracture orientation can be defined quite reliably at fracture density > 0.01; (d) the observed dependence of seismic wave field parameters on fracture face roughness and fracture density and orientation is consistent with effective model predictions.
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Numerical Simulation of Sonic Logging in 3D Anisotropic Elastic Media with Attenuation
Authors V.V. Lisitsa, E. Lys and G. ReshetovaThe paper presents an original approach to numerical simulation of sonic logging for tilted transversely isotropic media with attenuation. We suggest a new way to introduce attenuation to the stiffness tensor components for anisotropic media, so that the quality factors of the elastic waves are of a given quantity. The numerical approach itself is based on the Lebedev finite difference scheme on staggered grid applied to cylindrical coordinate system which is more efficient than well-known rotated staggered grid scheme. The numerical experiments, presented in the paper, were done to illustrate an impact of anisotropy and attenuation on a sonic logging, for example appearance of azimuthal component of the displacement velocity even in case of volumetric source acting at the axis of a fluid-filled borehole.
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Building Local Anisotropic Models using Joint Tomography of Seismic and Well Data
Authors A.V. Bakulin, M.J. Woodward, D. Nichols, K. Osypov and O. ZdravevaWe outline a concept of localized seismic tomography constrained by well information and apply it to building vertically transversely isotropic (VTI) velocity models in depth. We localize tomography to a limited volume around the well and eliminate non-uniqueness by supplementing surface seismic data with the well information. Finally, we regularize tomography with constraints of spatial smoothness in all three directions or any reasonable geological a priori information. As a result we recover the anisotropic velocity field around the well. We present a synthetic data example of anisotropic tomography applied to a 1D VTI model. We demonstrate two different cases of introducing additional information. In the first case tomography simultaneously inverts for all three VTI parameters including vertical velocity using a joint dataset that consists of surface seismic data and vertical checkshot traveltimes. In the second case seismic data and depth markers are used to invert for all three Thomsen parameters. Localized tomography confidently recovers correct global vertical profiles of anisotropic velocity field along the entire well length of 11 km. Anisotropic tomography with well constraints has multiple advantages over manual approaches and deserves a place in the portfolio of model-building tools.
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Risk Estimate of Location of Exploratory Wells and the Choice of the Order of Drilling on Ermolov Area
Authors I.V. Kolokolova and M.N. PopovaExploration works are very expensive, risky and have a lot of uncertainties. To appreciate how risky the carrying out of geological exploration on some area is, we have to first of all compare the expenses needed for geological exploration with the cost of received natural resources. The example of calculating the risks of prospective drilling on Ermolov area (Timan-Pechora province) is reviewed in the report. As a result of the calculations the order of drilling the prospective wells is defined
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Aggregation of Oil and Gas Resource Estimates of Local Objects under Geologic Risk
Authors V.I. Poroskun and N.M. EmelyanovaMethods of aggregation of resources' probable estimates of local objects under geological risk are considered in this work. The probable estimates of resouces of local objects are taking into consideration the the influence of two types of factors defining uncertainty of these estimates: uncertain geological model of the trap, received under the deficit of initial information and the unindentified productivity of the trap at the moment of the estimation of resources. Two types of probable estimates of resources are received: without geological risk (probable estimates of resouces in suboil) and with the action of two indicated types of factors - probable estimates of resources under geological risk. It was noted that the accounting of the geological risk has been identified the specific character of methodology of aggregation of probable estimates of trap's resources.Analytic method of aggregation of probable estimates of resources under geological risk was developed. Design formulas and demonstration example were made. The method is useful for the receiving of probable estimates of resources of prospects consisting of several traps.
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Economic Criteria in Decisions on Exploration Works
Authors A.A. Gert, N.A. Suprunchik, O.G. Nemova, K.N. Kuzmina and M.Y. SobolevThere are various problems on exploration work for which decision it is necessary to use economic criteria. Authors comparison of results of application of some methods of the economic appraisal based on net present value method, subject to uncertainty of the initial data and risks
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Application of ARCGIS for Monitoring the License Activity in Russia
Authors O.M. Polovinkin and L.N. NabievaThe Ministry of Natural Recourses exposes new blocks for licensing for exploration and production rights on a regular basis. For the course of the last two years, we carried out monitoring and analysis of this licensing activity. For this purpose, a huge amount of geological and geophysical data was collected, including information about wells, structure maps, maps of seismic coverage, the pipeline net and more. Working with such big data volumes creates specific problems in terms of representation, storage, accessibility and visualization. To handle these data appropriately, we adapted the ARCGIS software complex. The application of GIS for monitoring the licensing activity enables a fairly speedy evaluation of the main parameters of a certain region. The data are stored in separate layers, which can be piled, so that the user can represent any type and any size of data in any desired combination. So one can combine, e.g., the existing infrastructure and data representing the exploration history as input for an economical evaluation model of the license block under consideration.
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Fault Seal Estimation and their Role in Fluid–flow–An Example of Middle Miocene (chokrak) Fields West–Kuban Basin
Authors A.V. Derduga and M.V. GubarevThe technique of estimation fault seal ability is considered. By integrated structure maps, log data, detailed core information, wellbore and production data, geoscientists can now establish fluid flow across fault, model fault behavior and incorporate the result into reservoir fluid-flow simulators. This integrated process improves to reduce the uncertainty and risk with fault traps.
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Estimation of Reservoir Properties from Seismic Attributes and Well Log Data using Artificial Neural Networks
Authors M. Sitouah, G. Korvin, A. Al-Shuhail, A. Osman and A. AbdulRaheems method is costly and time consuming.To correlate reservoir properties with the continuously recorded well log data geologists generally use linear or non-linear regressions. This talk reports a comparative study of two types of neural networks, a Multiple-Layer Perception MLP, and a General Regression Neural Network GRNN. The viability of these techniques are demonstrated on log data and seismic from a reservoir in south of Algeria. This study utilizes the basic logs (GR, DT, VSH, RHOB, LLD and NPHI and five attributes to predict porosity, permeability and lithofacies in cored and uncored wells. The agreement between the core data and the predicted values by neural networks demonstrate a successful implementation and validation of the network’s ability to map a complex non-linear relationship between well logs and permeability and porosity. Also the results show that the application of the General Regression Neural Network GRNN gives a relatively better performance than the Multiple-Layer Perception MLP.
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New Software for Detecting Georisks on the Arctic Shelf Development
Authors A.N. Dmitrievsky, I.E. Balanyuk and Y.A. PoveschenkoСiteria effecting sea bed stability under submarine engineering works in the Arctic North conditions are development of gas hydrates on the sea floor, geothermic regime and faults tectonics
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Technique of Complex Geophysical Data Interpretation for Reefs Mapping
Authors A.A. Chernov and V.A. BoldyrevaThe analysis of gravity anomalies (scale 1:25 000) in researched site was carried out with the purpose of revealing and mapping of oil and gas perspective objects in a sedimentations. By results of seismic researches of prospect of this area is correlate to HC traps in ust-Pechora carbonate upper devonian sedimentations within the limits of a zone assumed (prospective) of organogenous constructions. The basic problem of interpretation of gravitational anomalies was the task of revealing and mapping of reefs and connected with them decompactions – potential HC traps. The prospects of the decision of this task were estimated proceeding from results of researches of gravitational fields above buried reefs constructions in various oil-bearing areas. Revealed thus by the numerous researchers of law of display of reefs in gravitational fields testify as to potential opportunities of gravity by searches of buried reefs, and allow to make a choice of techniques of interpretation of a gravitational field.
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