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2nd EAGE St Petersburg International Conference and Exhibition on Geosciences
- Conference date: 16 Oct 2006 - 19 Oct 2006
- Location: Saint Petersburg, Russia
- ISBN: 978-90-73781-64-1
- Published: 16 October 2006
1 - 50 of 209 results
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The Role of Russian Federation and Other CIS Countries for the Natural Gas Supply to Europe
By H. RempelNatural gas accounts for about 24 % of world-wide primary energy consumption, after crude oil and hard coal. Its share has increased in the last several years. This trend is expected to continue in the future (IEA 2005). Therefore the question arises, how the increasing gas demand in Europe can be assured? This question and the role of Russia and otger CIS countries will be analysed focussing on geology of hydrocarbon basins and giant gas fields, resource base, technical viability and contract security.
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The 21st Century's Strategic Reserve of Gas Industry Development are Russian Far-Eastern and Siberian Arctic Region
Authors V.V. Rybalcenko, V.S. Parasyna, V.S. Kovalenko and V.A. SkorobogatovThere is given analysis of modern condition of geological and resource exploration of sedimentary oil-gas-bearing basins of Russia as a whole and its eastern regions and also problems in sphere of further exploring of Russian Far-Eastern and northern Siberian regions. There is conducted qualitative assessment of gas-& oil-bearing capacity’s prospectives of Yamal, Gydan, Cara sea, the Yenisei-Khatanga deflection and Russian Arctic eastern seas.There are given the authors’ assessments of potential resources of Arctic regions. There is made conclusion on decreasing of gas-bearing prospectives in eastern direction. There are given results of risk-analysis of conducting of quest-prospecting works at West-Siberian megabasin’s north. There are made conclusions that exploring and exploitation of Russian Far-Eastern and Siberian northern and Arctic regions will be gas industry development’s strategy basis in the 21st century.
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The Genetic Evolution of the Petroleum Systems of Onshore Russia
Authors S. Creaney, M.P. Dolan, R.J. Ferderer, E. Fjellanger, N.W. McAllister, B.C. South, M.A. Sullivan and J.T. Van GorselThe genetic evolution of sedimentary basins involves basin formation, fill, and maturation of rocks and fluids within that basin.
The petroleum systems of Russia cover an extreme chronology from Pre-Cambrian to Recent for both source rock deposition as well as timing of petroleum emplacement. The oldest systems are driven by Riphean source rocks which matured under Vendian load and are reservoired in the ‘snowball-earth’ Vendian glacial deposits of East Siberia.
The evolution of these systems requires an understanding of Arctic, Tethyan, Atlantic and Pacific tectonics and their interplay.
As an example, the protracted Baltica – East Siberian craton suturing in the Uralian ruptures Paleozoic plays in West Siberia but sets up source deposition and loading in the Timan Pechora basin. The collapsed accretionary crust formed in West Siberia provides the substrate for Mesozoic deposition including the prolific Bazhenov source of the Late Jurassic. Trap formation occurs in West Siberia as a result of the far field effect of the India collision re-activating this older accretionary grain during peak petroleum generation.
This talk describes the petroleum systems of the major onshore provinces in Russia, linked to their controlling tectonic and depositional events.
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Deep Model Barents-Kara Region Based on Complex Interpretation along Geotraverses 1-3 AR
Authors N.M. Ivanova, I.V. Belyev, Y.G. Leonov, Y.I. Matveev and Y.V. RoslovThe Barents-Kara Region (BKR) has a compound structure, with a thick sedimentary cover, a heterogeneous basement and is complicated by rift structures. The specific tectonic structure of the BKR is mainly associated with repeated rifting. Therefore, the major objective was to study the topography and physical parameters of the granite-gneissic metamorphic complex and to determinate the age and composition of synrift complexes. The purpose of this article is to illustrate the special features of the deep structure of the Barents-Kara Region from recent deep seismic investigations and gravity/magnetic data along geotraverses 1-AR, 2-AR and 3-AR.
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The Potential of Oil-and-Gas Content in the Transitional Areas of the Separate Regions of Russia.
By V. SavchenkoThe regional geophysical works, which were recently carried out by the use of the high technologies and equipment, extended the potential of oil-and-gas content of the different structures, explored during the preceding years.
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Sequence Stratigraphy of West Eurasia and the Greater Caspian Region - Comparisons with Arabia
Authors P.R. Sharland, D.M. Casey, R.B. Davies, C.M. Hulka, D.B. Kemp, B.R. Kilner, D. Lodola, M. Ruddy and M.D. SimmonsFive years ago we demonstrated the occurrence across the Arabian Plate of 63 synchronous Maximum Flooding Surfaces (MFS) during the Late Precambrian – Phanerozoic.
It can be demonstrated that our sequence stratigraphic model can be successfully applied to the stratigraphy of West Eurasia (e.g. West Siberia, Timan-Pechora, Volga-Urals, Barents Sea) and the Greater Caspian (including the Black Sea) regions. Both MFS and sequence boundaries can be demonstrated to be correlative within the constraints of biostratigraphy.
There are profound hydrocarbon exploration and production implications for the application of the sequence stratigraphic model that we have developed. The model provides a precise and reliable framework for correlation and mapping and the subsequent identification of petroleum system elements such as lowstand reservoirs and transgressive source rocks.
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The Aquitaine Basin, Stratigraphic and Structural History, Petroleum Geology
Authors J.J. Biteau, A. le Marrec, M. le Vot and J.M. MassetThe Aquitaine Basin is located in the south-western part of France, extending from the Gironde Arch to the north, to the Pyrenean Mountain Chain to the south. It corresponds to a triangular shape domain of 35000 km2 acreage. This presentation aims to describe the history and the dominant Petroleum System of the Aquitaine Basin including both its northern and southern domains. This is an original approach compared to most of the presentations already published.
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Interpretation and Visualization of Thrust Sheets in a Triangle Zone in Eastern Potwar, Pakistan
More LessTriangle zone plays are common in the Potwar area of Pakistan. The Potwar Basin (Figure 1) is one of the oldest oil provinces. It is located in the western foothills of the Himalayas in northern Pakistan. It includes the Potwar Plateau, the Salt Range, and the Jhelum Plain. The Khairi Murat thrust-Dhurnal backthrust triangle zone in the northern Potwar deformed zone (NPDZ) and the Joya Mair triangle zone in the southern Potwar platform zone (SPPZ) are also well documented today. These tectonic settings hold several billion barrels of reserves, and significant amounts of hydrocarbons are being produced. We interpreted the Domeli-Dil Jabba triangle zone geometry which is the result of Tertiary Himalayan collision between Indian and Eurasian plates. The thrust and backthrust phases in the eastern Potwar are the result of a northwest-southeast Himalayan compression. This is the regional triangle zone in the eastern edge of Potwar which is the result of large, regionally extensive convergent thrust sheets.
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Modern Approaches in Seismic Modeling of the LUKOIL Oil Fields in Nenetskiy Region
Authors N. Tsyganova, A. Glebov, I. Khromova, S. Goretskiy and S. YakubovskiyOil fields of the Timano-Pechorskaya oil-and-gas province (located in Nenetskiy autonomous national area of Russia) characterized by the complicated geology with sharp facies variations by lateral, steep slopes of the structures, pinch-out zones presence, large number of tectonic faults and non-anticline traps. These result in large number of ambiguousness of the geological and geophysical interpretation and, thereby, bring to difficulties in geological modeling.
Acoustic inversion results which are used in seismic interpretation process have some advantages since, firstly, both seismic and well data are used in computations. Also prior geological information can be included that leads to more stable result.
In the paper results of the acoustic inversion of the southern part of Inzyreiskoe oilfield are discussed. Single impedance cube was calculated for two target intervals – Middle Devonian terrigenous and Upper Devonian carbonate complexes. For Upper Devonian complex we managed to perform the facial classification and particularly define the high cavernosity and karsting zones. The main results for Middle Devonian complex are improvement in seismic correlation in zones with complicated interference patterns, correction of pinching out lines of sand reservoirs and definition of consolidation zones and shaling outs of reservoirs.
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New Seismic and Geological Investigation of Upper Devonian Deposits in the Izma Depression of Timan-Pechora Oil-and-Gas
Authors I.V. Petrova, R.V. Khipeli, I.N. Kerusov, A.E. Evstigneeva and A.A. MesherskyThe results of a new seismic investigation of producting Sirachoy-Domanic (Upper Devonian) deposits in the Izma depression of Timan-Pechora oil-and-gas province are presented in the report. A detailed facial analysis with extracting prospective reef objects and sheet drapes has been made on the basis of 2D and 3D seismic investigations and wells data. The basis for the facial zoning and reservoir characteristics is: examination of the thickness distribution of Domanic and Sirachoy sediment, analysis of complex seismic attributes, results of the seismic inversion in the form of acoustic impedance sections. Many Domanic reef systems and connected with them hydrocarbon traps have been found on a comparatively small area. The problems of locating exploratory drilling on the oilfields and perspective structures have been solved, the course of high-priority seismic work has been chosen, main problems of seismic investigation of the organogenous objects have been defined.
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Oil-and-gas generator - accumulative systems of the Vankorski field in the Krasnoyarsk region
Authors NATALIA Kosenkova, V.A. Krinin, N.V. Lopatin and N.A. MalishevПиролиз керогена 151 образца керна и шлама скв. № 11 Ванкорской, впервые в этом районе вскрывшей разрез средней и верхней юры, а также генетические корреляции типа «нефть-нефть» и «нефть-битумоид предполагаемой нефтематеринской свиты» привели к идентификации нефтяной яновстанской свиты и газоконденсатной среднеюрской (малышевская и вымская свиты) в качестве основных источников коммерческой нефтегазоносности.
Установлено, что нефти продуктивных пластов неокома принадлежат к одному генетическому семейству, связанному в основном с яновстанским источником нефти.
Юго-восточный Пендомаяхский очаг генерации углеводородов интенсивно функционировал в эоцен-плиоценовое время. Критический момент для яновстанско-неокомской системы наступил в раннемиоценовое время, а среднеюрско-неокомской – в позднеэоценовое. С этим периодом времени был связан активный этап формирования залежей нефти и газоконденсата в Ванкорском месторождении, который продолжается и в настоящее время. Вертикальное перераспределение в пределах Ванкорской структуры было особенно интенсивным на новейшем этапе тектонической истории района.
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Risk Quantification of Geological Object Spatial Localization
Authors N.L. Ivanova and A.I. ArapovaThe geological risk quantification technique on perspective geological objects localizating, well position foundation and hydrocarbon resources estimation is considered. It bases on spatial reliability function and risk function stochastic estimation. We use structural mapping error and capacity characteristic crosswell-space error field simulation.
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3D Data Advanced Imaging for Reservoir Properties Analysis of the Dataset from the Illizi Basin, Algeria
Authors A. Iakovlev, N. Kushnerov, D. Golovanov, V. Solomatin and A. InozemtsevA set of advanced imaging solutions such as a refraction static, LIFT technology for Pre-migration imaging, Pre-STM, Pre-SDM were applied to process the seismic data set from the area OHANET GARA TISSELIT Block 245 South (Ililizi basin) Algeria.
A key challenge of this work was to produce high-quality seismic data to improve the description of reservoir heterogeneity by using 3D seismic to guide the interpolation of sparse network consisting just 2 wells to detect subtle stratigraphic and structural features over a range of frequencies with high-resolution and precise imaging in time and depth domain.
The special efforts were done to ground-roll and mid-range velocity noise attenuation, de-multiple work, seismic amplitude preserving for subsequent AVO analysis.
A detailed delineation of potential reservoirs has been obtained by integration of seismic and log data. Key to successful integration were (1) careful inversion via Neural Network Inversion of the 3D seismic data (2) accurate seismic-to-depth conversion of the inverted impedance cube, (3) reservoir characterization using AVO and (4) coherence cube calculation. The integrated model was used to formulate a set of recommendations for subsequent drilling plan implementation. In particular some subtle anticline structures with relatively high porosity-impedance and high-amplitude fluid-saturation was identified as potential development drilling targets.
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Seismic Inversion with Quantification of Uncertainty - Case Studies from Clastic Basins
By N.C. DuttaReservoir description using seismic data has two major components: inversion of seismic data to extract attributes such as P- and S-wave velocities and bulk densities, and relate those parameters to reservoir properties, such as rock and fluid types, fluid saturation, porosity and pore pressure through fundamentals of rock physics. In seismic acquisition, we have seen considerable advancement that contributed to the quality of the seismic data, especially in the prestack domain. These are: single sensor recording (a large number of channels/offset), accurate and calibrated source and receivers and their positions, digital group forming, and towing cables at shallow water depths to minimize swell noise. All of these enable us to access surface seismic data with high S/N and fidelity that often rivals the fidelity of the Vertical Seismic Profiles (VSP).
In this paper, we use high quality seismic data to carry out Full Waveform Prestack Inversion to extract reservoir parameters, such as porosity and saturation. We use rock physics principles to constrain our inversion algorithm and then quantify our uncertainty using Bayesian approach that accounts for errors in upscaling and noise in the data and the model. We illustrate the entire procedure with examples from several basins.
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Multiattribute Analyses in Gas Field Development (Molve Field Study)
Authors Z.S. Sladovic and I.F. FutivicSubject of this paper is seismic attribute analysis as the significant tool in Molve field development. The most important application of 3D seismic data, especially in development phase is characterization of inside reservoir quality based on attribute analyses. As Molve field is complex from stratigraphical, geological and other reservoir characteristic points of view the simple seismic attribute- reservoir parameter relationship couldn’t be establish.
There are four main lithologies in Molve field, and none of them is unified. Based on sedimentological and petrophysical analyses each lithology was separated on two main parts. At this point attribute - reservoir parameter relationship was established for “litofacies I” – limestone, but that approach was still insufficient for other lithologies. Multiattribute was created (the intention is to unify process for all lithologies; so time - frequency domain attribute was created). Now the field characteristics become highly correlated with seismic multiattribute. Probability of false correlation between reservoir characteristics and particular seismic attribute was determined based on (Kaklomey, 1997). This probability for multiattribute is around 15%.
Visualization of that attribute provides easily recognition of the area with better reservoir properties
As further drilling confirm, multiattribute specially delineates residual gas accumulations.
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Seismic Inversion Results for Prediction of Properties of Complex Reservoirs
Authors D.G. Kirnos, D.E. Kashcheev and A.M. GritzenkoA combined teqnique to predict reervoir properties from seismic inversion results is considered. Classification methods, multiple regression models and neural networks are employed to obtain predicted values of reservoir properties. A case history of porosity prediction, confirmed by subsequent drilling and geophysical survey, is provided.
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Study of Reservoir Properties and Hydrocarbon Saturation from 3D Seismic
Authors V.I. Ryjkov, M.B. Rapoport, I.K. Kondratyev and A.B. KrivitskyStudy of reservoir properties and hydrocarbon saturation from 3D seismic is suggested to carry out using the combination of three independent seismic technologies:
- Optimal seismic inversion
- Seismofacial analysis basing on geosonic modeling
- HC saturation prognosis basing on frequency-dependent seismic attenuation.
The result of investigation is the geological facial model of oilfield including distribution of porosity, reservoir thickness and HC saturation.
The examples obtained on oilfield in Western Siberia are provided.
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RT-Matrix Method for Direct Problems of the AVO
More LessTo advance the mathematical and computational treatments of direct problems of the AVO involving multilayered media, a new derivation of the RT matrix method (reflection-transmission matrix method) is presented. This method allows calculate the complete dynamic response including both the displacement and stress fields in a layered half-space. The stability and accuracy of the direct problem’s solution are studied by numerical experiments on the model data. The synthetic seismogram building is realized. Based on actual data performance capabilities of the AVO inverse problems’ solution are investigated using iterative selections of models of the medium. It is shown that selection of models of the medium using a realized algorithm allows tracing the alterations of the medium parameters (bed thicknesses) between key wells.
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Recovery of Thin Formation Properties through Seismic Amplitude Inversion
Authors G.A. Maksimov, G.N. Gogonenkov, S.A. Kirillov and V.A. LarichevThe paper proposes an effective method to recover a thin-formation structure (thinner than seismic wavelength) through amplitude inversion of surface-recorded low-frequency seismic events with due regard for downhole acoustic log data. As a result, spatial structure and properties of individual thin beds in a geologic unit are recovered between the wells at a scale less than seismic wavelength.
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Rock Properties of Complex Lithologies - Similarities Between Offshore Brazil and West Siberia
Authors O. Klarner, S. Klarner and B. UjetzRift related basins represent an important part of hydrocarbon bearing areas worldwide. In basins containing large flood basalts, volcanic rocks occur as major sediment source for potential reservoir sandstones. Examples from Cretaceous sediments in the Santos Basin, offshore Brazil, and Jurassic sediments in the West Siberian Basin are presented here. In contrast to pure quartz arenites, these sandstones contain a significant amount of feldspars, lithics and their diagenetic products which have a significant impact on reservoir properties. Although diagenetic products may preserve porosity at relatively deep burial, they normally reduce permeability and therefore production rates. The acoustic and elastic properties of the reservoirs are also affected. These types of complex reservoirs are rarely documented. Therefore, learning from case studies helps to understand similar reservoirs and to predict their properties in order to optimise exploration and production potential.
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The technology of integrated speed-spectral interpretation of filter-capacitor characteristics and petroefficiency of reservoirs in three-dimensional cross-borehole space petroefficiency of reservoirs in three-dimensional cross-borehole space
Authors M. Afanasyev, E. Kopilevich, E. Davydova, A. Petrov, A. Goncharov and J. AfanasyevaПрогнозирование ФЕС коллекторов в межскважинном пространстве производится по данным сейсморазведки и ГИС на основе их спектрально-временного и псевдоакустического преобразований с определением количественных спектральных по оси частот и времён атрибутов, а также псевдоакустической скорости. Эти сейсмические атрибуты сертифицируются по принципу наилучшей корреляции с ФЕС и интерпретируются комплексно с использованием искусственных нейронных сетей, на выходе которых распределение в пространстве удельной ёмкости и гидропроводности коллекторов.
Технология обладает патентной чистотой и успешно внедрена в сейсмогеологических условиях Западной Сибири и Тимано-Печорской НГП
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Modeling and Inversion of Sonic P and S Wave Velocities at the Mallik 5L-38 Gas Hydrate Research Well
Authors J.G. Rubino, C.L. Ravazzoli and J.E. SantosUsing an interval of real log data from the Mallik 5L-38 Gas Hydrate Research Well, we estimate empirical relations for some mechanical properties of the gas hydrate frame. This is an important problem for geophysical exploration in gas hydrate bearing sediments, a subject which has not received as much attention as it deserves from the researchers in this field.
The theoretical velocities used to model the sonic logs are computed using a Biot-type formulation combined with known petrophysical models for shaley sandstones.
The empirical results are also applied to obtain estimates of gas hydrate saturations at a different depth interval from sonic and density log data, showing the applicability of this approach.
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Authenticity of Hydrocarbons Deposit Prediction Rise on a Base the Integrated Model of Field
Authors A.P. Sorokin, S.O. Slobodyanyuk and V.V. SirchenkoAuthenticity of prediction of hydrocarbons deposit, at the searches and exploring of hydrocarbons reservoirs by geophysical methods, relies oninforming of every method in concrete geological condition and is characterized by the factor of definiteness 0
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Prestack Interpretation in Interpreter's Environment
Authors M.M. Popov, D. Mair and N. Xuan NamIn the conventional approach of interpreting stacked seismic, the goal of a prospect mapping is to define the geologic framework and stratigraphy. Correlating well data with poststack seismic attribute volumes provides some hints to possible hydrocarbon presence and reservoir quality away from wells. However these characterized volumes have already blended the seismic response of different offsets, and can be further distorted by the stacking process. To understand the composition of the framework that is lithology and pore fluid away from well control requires prestack interpretation.
For decades, interpreters have used poststack seismic volumes as their primary data type due. In contrast, prestack seismic data has been very difficult to access from a standard seismic interpretation environment, partly due to hardware limitations. Its use has been limited to specialists such as AVO experts and seismic processors. Nowadays, with access to affordable hardware providing sufficient disk space and memory to handle huge prestack datasets, the potential to work with prestack data exists. Most importantly, new geophysical tools permit everyday interpreters to view and analyze this prestack seismic data in an integrated interpretation environment.
This paper describes a case study whereby analyzing prestack data in the interpreter's environment helps to see clearly differences in the prestack response to hydrocarbon or water at the reservoir.
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Structure of the Jan Mayen Fracture Zone, Norwegian-Greenland Sea - Insights from the New Aeromagnetic Survey JAS-05
Authors L. Gernigon, O. Olesen, J. Ebbing, J.O. Mogaard, C. Pascal, S. Wienecke, J. Mondt, O. Norvik, M. Sand and O. SteenIn order to better constrain the Cenozoic evolution of the Norwegian-Greenland Sea and contiguous margins, a new aeromagnetic data (JAS-05 survey) was acquired in the Eastern part of the Jan Mayen Fracture Zone during autumn 2005. We present preliminary results and interpretation of this survey. The main faults, structure and magnetic anomalies have been re-interpreted using a systematic comparison between bathymetry, gravity, magnetic patterns and available seismic data. Magnetic chrons have been identified and has been used to provide accurate Cenozoic ages for the oceanic basement and overlying sedimentary sequences, identified on seismic. The new magnetic survey and integrated study allow us to discuss the tectonic and magmatic evolution of the Jan Mayen Fracture Zone and its geodynamic implications
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Forecast of the Mineral-Raw Prospective Areas, That Is According to Results of Integrated Processing and Interpretation
Authors S.A. Kaplan, E.N. Cheremisina, A.S. Kireev, V.I. Galuev and S.S. MalininaThis paper presents the methodology of integrated processing and interpretation of research data on control geophysical profiles. The general scheme of integrated analysis of geological information is adduced. Methods of constructing environment models based on data from separated geophysical methods are represented, methodology of getting block-layered locally-homogeneous model of Earth’s crust is proposed. Results of forecast of favorable zones for formation of mineral deposits and conditions on Eastern Siberia and Far East profiles are represented
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The Geodynamic Model Central - Aldan of Region (CAR) and Prediction
More LessThe offered operation has allowed on the basis of a dynamic model Central - Aldan of region, using the program COSKAD 3D, to carry out prediction of plants under search operations on ore gold
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Deep Structure and Geodynamics of the Pre-Mesozoic Sedimentary Successions within the Northern West Siberia
Authors S.L. Kostyuchenko, V.A. Erkhov and V.Y. BulavinovThe data derived from deep CDP, DSS and conventional seismic study of the territory of Northern West Siberia give evidences to suggest different stages of evolution of the region. The plate tectonics took place up to the Middle Palaeozoic. The interaction of a mantle plume and earth crust causes the large-scale sedimentary basin formation during the Middle-Upper Palaeozoic. The rift occurred in the end of the Palaeozoic up to Early Triassic time, and after these, general subsidence of the lithosphere was resulted by formation of the West-Siberian sedimentary province. We conclude that, in the area of study, 4-6 km thick carbonate-terrigenous sedimentary complex exists beneath the Mesozoic to Cenozoic oil and gas bearing cover.
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Deep Structure of the Pre-Mesozoic Consolidated Basement of the West-Siberian Geosyneclise and “Deep” Geological-Geophysical and Geodynamic Factors of Hydrocarbon Deposits Localization.
Authors A.S. Egorov, V.N. Muchin, A.I. Atakov and E.Y. ErmolinResults of geological-geophysical modeling of the consolidated basement of the West-Siberian geosyneclise with the use of modern-day regional CDP seismic profiling data are presented. The estimation of potentialities of the multifactor prognostic technology with the aim of “deep” factors of hydrocarbon deposits localization is considered.
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Technology of MT Data Interpretation and Results Obtained at Geotraverses
Authors V.P. Bubnov, E.D. Aleksanova and A.G. YakovlevTechnology of magnetotelluric (MT) data interpretation and results of MT investigations along geotraverses in Eastern Siberia are considered. New information about resistivity structure of the sediments and consolidated crust was obtained. Thick conductive Riphean layers, supposed to be good collectors, were revealed in Irkenyevsky aulacogen and Tungusskaya syneclise. It is shown that in geoelectric conditions of Yeniseisky range MT method allows to study only the upper 10 – 15 kilometers. Two types of the Earth’s crust are determined within the Siberian craton. Crust of the first one contains crustal conductive layer and corresponds to hydrocarbon perspective areas. In the crust of the second type this layer is not developed.
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Seismography as Effective Problem Solving Method in Ore and Oil Geology and in the Siberian Earth's Crust Study
Authors A. Salnikov, V.L. Kuznetsov and V.M. MarkovДля повышения геологической эффективности сейсмических исследований, в том числе проведенных в прошедшие годы, предлагается использовать способ сейсмической томографии на временных задержках волн в первых вступлениях, зарегистрированных при работах методами отраженных и преломленных волн.
Для решения обратной задачи применяются специальные двухмерные временные поля, что позволяет объединить в единую систему времена прихода волн при наблюдениях разной детальности, в том числе при отсутствии корреляционной увязки отдельных годографов. В качестве интерпретационной модели принята непрерывная двухмерно-неоднородная модель.
Разработанная технология сейсмической томографии широко применяется при решении различных задач нефтяной и рудной геологии и при изучении глубоких зон земной коры Сибири: изучение самой верхней гетерогенной части земной коры в рудных районах, что позволяет прогнозировать новые рудные узлы и изучать их структуру; изучение структуры и строения, а в комплексе с данными бурения, и состава палеозойских нефтегазоносных образований в Западной Сибири; позволяет освещать внутреннюю структуру глубоких зон земной коры, обеспечивая выявление волноводов, зон дезинтеграции, глубинных разломов.
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Depth-Velocity Model Based on Regional Seismic Data
Authors V.V. Kasianov and I.U. KulakovaThe calculation of reflected compressional wave velocities based on regional seismic survey data for further depth conversion and the compressional wave field study aimed to identify blocks and areas in Yamal-Nenets autonomous district for detailed prospecting at insufficient deep drilling information.
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Which Parameters Control Seismic Attenuation in a Fractured Porous Rock?
Authors B. Gurevich, M. Brajanovski, R.J. Galvin and G. LambertTo analyse which parameters (fracture length, thickness or spacing) control the frequency dependence of attenuation and dispersion, we consider two theoretical models. The first model considers fractures as planes of weakness (or highly compliant and very thin layers) of infinite extent. In the second model fractures are modelled as thin penny-shaped voids of finite radius.
In both models attenuation exhibits a typical relaxation peak around a normalised frequency of about 1. This corresponds to a frequency where the fluid diffusion length is of the order of crack spacing for the first model, and the crack diameter for the second. This is consistent with an intuitive understanding of the nature of attenuation: when fractures are closely space, the waves reflected/scattered by cracks interfere with each other, with the interference pattern controlled by the fracture spacing. Conversely, if fracture length is smaller than spacing, then fractures act as independent scatterers and the attenuation resembles the pattern of scattering by an individual crack.
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The interpretation of petroefficiency of fractured reservoirs
Authors D. Reznikov, E. Kopilevich, E. Davydova, M. Afanasyev and A. PetrovПрогнозирование коэффициента нефтепродуктивности трещинных коллекторов производится по данным сейсморазведки МОГТ, ГИС, испытаний скважин на основе количественных спектрально-временных и псевдоакустических преобразований сейсмических преобразований сейсмической записи и кривых ГИС с последующим интегрированием спектрально-скоростных атрибутов с использованием искусственных нейронных сетей для определения коэффициентов емкостной дифференциации (КЕД) глинистых трещинных коллекторов, интегральной удельной емкости (q) карбонатных трещинных коллекторов КЕД и q коэффициента нефтепродуктивности Кнпр = Q/Δp, где Q – дебит нефти, Δp – перепад давления в скажине. Технология обладает патентной чистотой и успешно внедрена в сейсмогеологических условиях Западной и Восточной Сибири.
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PS-Wave Azimuthal Anisotropy in a North American Carbonate Basin
Authors S. Roche, B. Mattocks, J. Li and S. RonenIn an onshore example from a US carbonate basin, an embedded multicomponent test exhibits good PS-wave signal quality at the depth of interest, and all the expected characteristics of converted waves in azimuthally anisotropic media. In particular, there are clear azimuthal polarity reversals on the transverse receiver component, separated by null amplitudes defining the symmetry planes of the natural coordinate system; azimuthal velocity variations on the radial component then distinguish the specific symmetry plane aligned with maximum horizontal stress. The cumulative anisotropy is in good agreement with regional horizontal stress from borehole breakouts.
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Applying the Side-View Seismic Location Method (SVSL) in Complicated Geological Conditions
Analyzed are results of applying the Side-View Seismic Location method (SVSL) in combination with other seismic methods to solution of main problems of HC exploration in complicated geological settings of Orenburg region and Kuyumba oil field in East Siberia. Combination of SVSL and other seismic methods (CMP) allows solve such problems as building a structural model, mapping of fractured zones and fluid migration pathways. By way of examples considered is solution of these problems for the south of Cis-Ural through, particularly, for the Akobinsk area featuring a material effect of salt-dome tectonics. The second part of the paper presents results of applying SVSL to mapping the open fracturing of rocks, refining the geological model of Riphean complex of East Siberia (Kuyumba oil field) in combination with the structural seismic (2D CDP), and identification of fractured zones which are promising drilling targets. Proposed is a technique for identifying reefogenic structures in the depth interval of Riphean complex. This allows substantially improve the reliability of geological predictions when selecting optimal drilling sites to achieve maximum oil flow rate in exploratory wells.
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Noise Amplitude Analysis of Collocated VectorSeis and Geophones Groups
More LessОдним из требований, предъявляемых заказчиком работ к качеству полевого материала, является контроль максимально допустимого уровня случайных шумов (до первых вступлений) на профиле. В большинстве случаев максимально допустимое значение шума для данной площади обычно известно либо по результатам предыдущих работ, либо по результатам предварительно проведенных опытных работ, и задается в микровольтах.
В последнее время все большее распространение начинает получать сейсморазведка с использованием точечных многокомпонентных цифровых акселерометров. Главным отличием данного метода является регистрация полного волнового поля и отказ от группирования сейсмоприемников.
Многокомпонентный цифровой сейсмоприемник представляет собой акселерометр, регистрирующий ускорение, в отличие от стандартного геофона, измеряющего скорость смещения частиц грунта. Вследствие этого при работе с акселерометрами нельзя использовать максимально допустимый уровень шумов, рассчитанный для групп геофонов. Часто, при применении акселерометров на конкретной площади мы не имеем достаточного количества статистических данных для определения уровня шумов в микрогалах. В данной работе исследуется возможность использовать для определения этого уровня максимальный шум групп геофонов.
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Time Processing of Multicomponent 3D Survey Acquired in West Siberia, Russia
Authors Z. Tlemissova and D. YanchakMulticomponent data acquired by TNK-BP in 2005 was the first 3D/3C survey shot in West Siberia, Russia. This study covers the main issues and challenges of the 3C processing and the behavior of PS waves in the subsurface geology of West Siberia as compared to P waves.
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Use of a Vertical Component of Seismic Shear Waves
Authors YU.P. Bevzenko and V.A. ZozulyaWide-scale implementation of multi-component seismic exploration is constrained by subsoil users’ doubt in its efficiency due to lack of information acquired in field conditions and confirmed by drilling and field operation results. In such situation shear & converted wave data obtained in the process of conventional seismic exploration with monotype P-waves is useful to justify multi-component seismic prospecting. The most favorable conditions for studying a vertical component of shear and converted waves are found in prePolar areas with a high-velocity 500 m thick permafrost layer on a surface of the interval under study. Use of additional information allows to define requirements to projects of multi-component seismic exploration performed using borehole explosions and nonexclusive sources of a vertical action, as well as, in some cases, solve geological tasks at relatively shallow depths. A result of the research works performed since 1997 is a recommendation to realize a rational land multi-component 2D seismic exploration based on a highly-mechanized 3-component telemetric system “MarshLine” being manufactured by a Russian company “Sea Technology” for working in transit zones.
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Multicomponent OBC (4C) Time Imaging over Pamberi, Offshore Trinidad
Authors T.D. Johns, C. Vito, R. Clark and R. SarmientoResults from the P-P and P-Sv prestack time migration of a four-component (4C) OBC seismic swath test acquired in 2004 over the Pamberi area in Block LRL offshore Trinidad, are presented. A description of the processing applied to the multicomponent seismic data, through curved-ray anisotropic Kirchhoff prestack time migration for both the compressional P-wave and mode-converted PSv-wave, is provided. Mode-converted shear-wave data acquired from 4C surveys allow for imaging where conventional seismic data are perturbed due to the presence of shallow gas or fluid in the pore spaces of the rock. Furthermore, mode-converted shear waves propagate with a different raypath than that of the compressional wave, thereby providing an alternative illumination of the subsurface target. As both the P-wave and S-wave record independent measurements of the same subsurface, more reliable rock properties can be uniquely determined, allowing for improved reservoir characterization and lithology prediction. A conventional towed-streamer 3D was acquired over the Pamberi area in 2003, but failed to resolve adequately the target reflectors comprising the reservoir under the main growth fault. Therefore, the purpose of the 4C survey was to evaluate the potential of long-offset multicomponent technology for resolving stratigraphic interpretation in areas of complex challenging geology.
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Shear-Wave Seismic and VSP with Virtual Sources
Authors A.V. Bakulin and R.W. CalvertShear-wave seismology holds great promise but always remains small niche activity due to a variety of operational and subsurface limitations. In this study we demonstrate that the Virtual Source method can overcome many of these limitations and revive shear-wave seismology. With an array of sources at the surface this method allows us to obtain a Virtual Shear Source at the location of each downhole geophone in a well. Firstly, in certain cases it allows us to generate pure shear-wave energy without P-wave contamination using conventional P-wave sources even in a marine environment. Secondly, we can construct SS images of the subsurface even through a complex near-surface for which the velocity model is unknown. Thirdly, we can control the polarization. All this is at a price of placing geophones in the subsurface and making downhole recordings. This price tag is expected to decrease with greater use of permanent downhole monitoring, cheap wells and instrumented oilfields.
We will show examples of SS images obtained through a complex near-surface and show shear-wave checkshots generated with the help of P-wave sources even in a marine environment. This
development may lead to a renaissance of shear-wave seismology especially for permanent seismic monitoring.
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Full-Wave Imaging Projects Using Multicomponent Digital Sensors in Russia
Authors T.E. Galikeev, A.P. Zhukov, I.P. Korotkov and A. BurlakovTwo 3-D multicomponent datasets were acquired in Western Siberia and analyzed. The same type of digital 3-C accelerometers used for data recording were used with different types of sources (dynamite and VibroSeis). Data analysis suggests that the source and near surface conditions can impact the quality of recorded converted wave data, while the vertical P-wave component is of a high quality and equally interpretable when compared to geophone data acquired in the same area. Absorbing properties of the overburden in Western Siberia limit frequencies of converted waves up to 20-30 Hz depending on intensity of near-surface frost penetration. Therefore, an adequate effort should be spent on generating low frequencies in the source’ spectrum. Production sweeps rarely start below 10 Hz due to equipment restrictions and applied sweep tapers further reduce full energy effort spent on low frequencies. Absence of low frequencies in the source manifests itself by a very narrow frequency spectrum of converted waves in the data acquired with VibroSeis. Although, during processing and utilizing data rotation (data were recorded with 3-C digital sensors) the quality of C-wave stacks were improved.
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Advances in Multicomponent Exploration
Authors S. Grion, S. Roche, J. Gibson, B. Mattocks, S. Ronen, H. Watt and K. PoplavskiiMulticomponent (MC) seismic data are gaining importance as an exploration tool for difficult targets. Vector acquisition of seismic data in three orthogonal directions (3C) allows for the recording of both compressional (P) and shear (S) waves. These respond differently to fluid and solid combinations in the subsurface and the joint use of both wave modes provides many potential benefits. Applications relate to structural imaging (seeing through gas clouds, better fault definition, improved near-surface resolution), fracture characterization (density and orientation), fluid discrimination and estimation of lithology (sand/shale, dolomite/anhydrite). Furthermore, vector recordings allow for improved noise attenuation with respect to conventional P-wave records.
This paper provides an overview of multicomponent technology and focuses on the techniques and advances that are improving viability and includes theory and practical examples of how multicomponent technology is improving the ability of the industry to find and produce more oil and gas.
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Minimization of the 4C Alford Data Matrix for Non-Orthogonal PS-Wave Reflection Modes
By J.E. GaiserJoint inversion of P-waves (compressional waves) and PS-waves (converted P to S-waves) is becoming more important for pore pressure prediction, time-lapse effects and characterizing the stress and fracture state of reservoirs. However accurate results will depend on how well the principal S-wave (shear-wave) directions can be determined in anisotropic media. PS-wave reflection coefficients in azimuthally anisotropic media produce a set of non-orthogonal amplitude modes that can complicate the estimation of principal S-wave directions.
The purpose of this study is to show that a conventional Alford rotation provides the correct principal direction for non-orthogonal PS-wave modes in azimuthally anisotropic media when reflection coefficients vary azimuthally. Fast and slow S-wave components of 4C (four component) Alford data are examined in terms of azimuthally anisotropic PS-waves reflection coefficients. Results for orthorhombic media illustrate that the Alford data matrix is diagonally dominant when properly aligned with the principal directions. A synthetic data set consisting of a 5-layer model representing vertical fractures of different orientations demonstrates that conventional Alford rotation and layer stripping will give the correct principal directions when the off-diagonal traces are minimized.
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Numerical Modelling of Seismic Character of Depositional Sequences
Authors B. Gurevich, A. Gerhardt, G. Lambert, C.M. Griffiths and C. DytAnalytical and numerical models of sediment transport and deposition are being increasingly used to investigate controls on sediment variability in depositional sequences. In this paper we consider the stratigraphic response to eustatic sea-level (amplitude and period) and local controls, such as sediment supply and subsidence, and their impact on the resulting reflectivity along a notional well situated in an outer neritic location. The development of key stratal surfaces shows a systematic relationship with respect to the various stages of an aggradation curve.
The results of seismic modelling indicate that seismic events related to sediments deposited under the influence of systematic changes in sea level show a distinctive pattern that approximates the derivative of the original seismic wavelet, while their amplitudes indicate the degree of evolution along the stages of the aggradation curve. If appropriate conditions are met, this distinctive character can be used to distinguish such seismic events from the ones associated with unconformities or layers not directly associated with these controls.
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3D Finite-Difference Modeling of Borehole Wave Propagation
Authors V.A. Tcheverda, V.I. Kostin, D.V. Pissarenko and G.V. ReshetovaFinite-difference (FD) method for 3D simulation of sonic waves propagating in a borehole and surrounding 3D heterogeneous elastic medium is presented. It is based on explicit second-order staggered grid FD scheme that solves the first-order elastic wave equations in cylindrical coordinates. Special modification of Perfectly Matched Layer (PML) for cylindrical coordinate system is developed and implemented. Essential 3D nature of the waves processes for realistic models claims necessity to use parallel computations. Parallelization is performed on the base of domain decomposition approach and implemented under Message Passing Interface (MPI). Result of numerical experiments is presented.
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Wave Propagation in Rocks and Granular Materials Modelled as 1D Heteromodular Elastic Medium
More LessWe consider 1D non-stationary essentially nonlinear dynamic problem for heteromodular elastic medium. Heteromodular medium reacts differently to the tension and compression and therefore presents strongly nonlinear behaviour at infinitisemal deformations. It is subjected to the harmonic force which was "switched on" at zero moment of time. We consider the case when the difference in elastic moduli for tension and compression is small, and construct asymptotical solutions for large times. The analytical results are verified numerically. We construct both near and far-field asymptotics, analyse spectral properties of the problem.
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Tube-Wave Interaction with a Fluid-Filled Circular Fracture of a Finite Radius
Authors S.R. Ziatdinov, A.V. Bakulin and B.M. KashtanTube waves in boreholes are used for characterizing formation properties and hydraulic properties of fluid-filled fractures and permeable zones intersecting wellbores. At low frequencies there is a wellknown approximate formalism describing reflection/transmision of tube waves on layer boundaries and infinite fluid-filled fractures. However for fractures or washouts of finite size one can only use numerical methods such as finite difference that are time-consuming and do not provide physical insights.
Here, we extend existing formalism to analyze reflection/transmission of tube waves on a circular fluid-filled fracture/washout of an arbitrary finite size. We break the problem into three tasks. First, conversion of tube waves into guided waves is modeled using method of Kostek et al. (1998). Second, we derive new analytical solution for reflection of diverging guided slow wave from a fracture tip using 2D approximation. Finally, we derive conversion coefficient describing transformation of imploding guided into tube waves in a borehole. Combining three solutions, we obtain simple analytical representation of a total wavefield in the borehole as a superposition of upgoing and downgoing tube waves generated at the fracture intersection and borne by incoming guided waves and their multiples. New solution is in good agreement with finite difference computations.
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The Analysis of Microseisms Spectrum at Prospecting of Oil Reservoir on Republic Tatarstan
Authors E.V. Birialtsev, I.N. Plotnikova, I.R. Khabibulin and N.Y. ShabalinAre represented the results of the analysis of a microseisms spectrum, which is received at prospecting of small oil reservoirs on territory of Republic Tatarstan. For this analysis it is used the method based on revealing of peak abnormal high amplitude in a range of 1-10 Hz. Are discussed two alternatives hypothesis about nature of this peak over oil reservoirs. Based on experimental data it is shown, that the hypothesis of resonant amplification of microseisms in the resonator between daylight surface and oil reservoir is more adequate. It is shown, that it is can observe oil reservoirs, the border a sedimentary cover - the crystal and of other geological structures, such as active fault, as a peak on microseism spectrum.
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