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5th EAGE St.Petersburg International Conference and Exhibition on Geosciences - Making the Most of the Earths Resources
- Conference date: 02 Apr 2012 - 05 Apr 2012
- Location: Saint Petersburg, Russia
- ISBN: 978-90-73834-23-1
- Published: 02 April 2012
1 - 50 of 178 results
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Overview of the Cretaceous Evolution of the North-western Barents Sea
Authors A. Escalona and S. OlaussenThe northwestern Barents Sea is mostly under explored and covers a large part of the Norwegian and Russian continental margins. Most reservoirs are Carbonifeours to Jurassic in age, and little attention has been paid to the Cretaceous intervals which may hold enormous potential. After the newly discovered liquid petroleum system in the western margin of the Barents Sea (i.e. Skrugard) the link between the conjugate margin offshore North East Greenland and western Barents Sea becomes of particular interest. In addition, the northern boundary of the Cretaceous interval represents a key transition time in the evolution of the northern Arctic region which affected large areas of the Barents Sea and was the time where most of the North American arctic basins developed. Plate tectonic models during this time are quite uncertain due to the lack of constrains, but until the late Jurassic/early Cretaceous, most arctic basins seem to be related. In this presentation, an overview of the Cretaceous evolution of the Arctic, with focus on the plate setting of the northwestern Barents Sea is provided in order to highlight areas that require further analysis to evaluate the petroleum potential.
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The History of Development and Prospectives of the Jurassic Deposits on the Barents Sea Shelf
Authors A.A. Suslova, A.V. Stoupakova, Y.K. Burlin and R.S. SautkinReservoirs of Jurassic complex in the Barents Sea sediments were formed under transgressive-regressive regime of sedimentation in the midst of the marine basin’s general transgression. In Jurassic time eastern and western sectors of the Barents Sea basin developed as a single basin under calm tectonic environment. This gives the possibility to identify general sedimentation cycles within the limits of this region.
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Geological Structure and Petroleum System of South Kara Basin
Authors N.A. Malyshev, V.A. Nikishin, V.V. Obmetko, B.I. Ikhsanov, Y.V. Reydik, K.A. Sitar and D.S. ShapabaevaGeological model of South Kara basin (SKB) based on 2D seismic and regional lines 2-AR and 3-AR. The SKB is filled by Upper Triasic(?)-Cenosioc clastic sediments together with the Late Permian(?)-Mid Triassic synrift megasequence. The rifts base is tracked at the depth up to 11-12 km. Using new seismic data, we identify grabens and semi-grabens at the base of the basin. They are filled by partly deformed sediments. The 3D basin model is done and shows oil and gas windoows. Many structures identify on Paykhoy-Prinozemelskiaya monokline such as Universitetskaya, Vikulovskaya and Tatarinovskaya.
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Constraints on Magnitude of Cenozoic Uplift and Petroleum Systems Modelling for the Russian Barents Sea
By P.O. SobolevThe Cenozoic regional uplift remains very poor investigated for the Russian part of the Barents Sea. Several methods were used to estimate magnitude of the uplift and erosion for the Eastern Barents Sea. First method was related with using of generalized porosity-depth trends. Geophysical well logging data from the Russian Barens Sea (about thirty deep offshore wells) were compiled and processed. The joint interpretation of sonic, gamma-ray, resistivity, spontaneous potential logs were used to calculate porosity and shale fraction for siliciclastic rocks. Comparison of smoothed exponential porosity-depth curves from different wells reveals the rate of compaction for the different kinds of sediments (sands, silts and shales) and different level of erosion. Similar results were obtained with Magara’s approach for sonic logs of shales. We used vitrinite reflectance data for the independent evaluation of the uplift and for calibration. Combining the data on wells we have determinated uplifts ranging from 300 m in the south (Pechora Sea) to 700 m in the central part of the South-Barents deep and to 2 km in the Franz-Joseph Land. The magnitude of erosion increase eastward as well. Seismic profiles and structural maps were used to trace and interpolate the estimates of uplift between wells.
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Looking for the Giants - Sedimentation and Basin Modelling Application for South Kara Basin
Regional modeling approach including Sedimentation and Basin modeling had been applicated with use of Beicip Franlab software tools (Temis and Dionisos) in Kara Sea regional studies at Gazpromneft Science and Technology Centre. As a result of the modeling, the possibility of further discoveries of giant fields in South Kara Basin is pretty high. Although gas accumulations are predominating in the basin, oil-and-gas condensate fields with sufficient part of liquid hydrocarbons could be found in the areas where the source rocks facies and maturation is favorable. We assume that the main source for the hydrocarbons, accumulated in the South Kara Basin in Cretaceous reservoirs are the Uppermost Jurrasic, as well as Lowermost and Middle Jurrasic shales with mostly marine type of kerogen. Lower Cretaceous (apt-alb) sediments enriched in terrigenous organic matter and containing coaly layers never entered the “oil window”, so they could produce only shallow biogenic gas, which can’t be assessed quantitatively using basin modeling technique and may affect the pools, mixing with the thermogenic gas from Jurrasic source rocks. Further studies and new geological and geochemical data required to refine the model and make sure that the geological and geochemical model assumptions were correct.
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Lower-upper Permian and Triassic Seismostratigraphic Complexes in the South-eastern Barents Sea
Authors D.A. Norina, G.S. Kazanin, S.P. Pavlov and A.V. StoupakovaPresent evaluation of Lower-Upper Permian and Triassic clastic deposits in the Russian Barents Sea shelf are based on detailed geological and seismostratigraphic interpretation of regional seismic lines acquired by MAGE in 2007-2009. Active uncompensated subsidence of South Barents and pre-Novaya Zemlya depressions in Early-Late Permian and sea level changes led to the formation of three sequences in which low-stand, transgressive and high-stand system tracts were identified. Low stand system tracts infill central parts of the basin and contain high-amplitude discontinuous reflections which may indicate sandstones of basin fans. High-stand system tracts are characterized by sigmoid progradational reflection pattern with high-amplitude facies at clinoform bends corresponding to perspective shallow-water reservoirs. Pemian-Triassic erosion unconformity is well-traced at the basin margins. Triassic strata in the study area were formed in deltaic, coastal and shallow-marine conditions under constant compensation of basin subsidence with large volumes of sediments. They are characterized by hummocky high-amplitude reflection configuration at basin margins and low-amplitude sub-parallel discontinuous seismic pattern in the central parts. Bright, parallel, continuous reflections in the Middle Triassic correspond to sea level rise and shale deposition. Structural and stratigraphic traps were identified in Triassic complex.
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Hydrocarbon Potential of Riphean-paleozoic Deposits of Taimyr
By V.A. BaldinRegional 2D seismic explorations of enhanced depth were carried out at the beginning of XXI century for the first time. They allowed together with other geological-geophysical data fundamentally change the model of structure of Yenisey-Khatanga regional depression, Taimyr mountain area, Siberian Platform and Western-Siberian plate. New largest (of superorder and I-II orders) structural-tectonic units were defined on the north of Siberia. Hydrocarbon potential of north-east of Western Siberian, north-west of Siberian Platform and western part of Taimyr fold system was evaluated based on the new attitude. The new hydrocarbon potential sedimentary basin in Riphean-Paleozoic deposits (South-Taimyr oil-and-gas province) was defined on the southern part of Taimyr belt of thrust faults. On the north-west of Siberian Platform the Igarsko-Norilsk oil-and-gas province was defined where the main zones of potential oil and gas accumulation may be megabars with accessible for drilling Riphean-Paleozoic complexes.
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Hydrocarbon Systems of Tatar Strait Sedimentary Basins and its Prospective Production Analysis
More LessThe article discribes the main stages of the section hydrocarbon productivity forming. It is based on the generation and migration processes and their evolution during the geological history. The main result of the project is the new objects for exploration studies and phase composition prediction for the possible hydrocarbon deposit.
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Geological Prerequisites of Formation of Big Oil and Gas Centers in Eastern Siberia
Authors V. Kharakhinov and S. ShlenkinTheoretical estimates of oil-and-gas generation in East Siberia revealed by our complex analysis allowed us to draw a conclusion that oil-and-gas potential of East Siberia is underestimated.
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Using Onshore Geology to Predict the Hydrocarbon Potential of a Frontier Arctic Region - The Laptev Shelf, East Arctic
Authors J.S.K. Barnet, O.J. Ralph, C.M.J. Davies, A. Davies and M.D. SimmonsWith growing interest in the hydrocarbon potential of the circum-Arctic, increasing attention is turning to the frontier shelves of the East Arctic such as the Laptev Shelf. No deep wells have been drilled offshore, with stratigraphic predictions based on study of onshore outcrops, including the Taimyr Peninsula, northern mainland Siberia and New Siberian Islands. The discovery of hydrocarbon fields in Jurassic-Early Cretaceous clastics of the Yenisey-Khatanga and West Siberian basins, and in Permian-Triassic clastics of the Lena-Anabar Basin, highlight Late Palaeozoic-Mesozoic potential in the neighbouring offshore. Early Cretaceous post-orogenic and Late Cretaceous-Palaeogene syn-rift coal-bearing clastics could represent the most significant source rocks. Marine organic-rich facies of the PETM and Middle Eocene “Azolla” event may constitute oil-prone source rocks in restricted grabens. Oligocene-Early Miocene sandstones and Late Miocene-Pliocene marine shales could represent regional reservoirs and seals respectively. We have conducted a study of the region using a global sequence stratigraphic model, drawing on data available in the public domain. This interpretation allows enhanced understanding of the shifting distribution of transgressive and regressive reservoir facies. When placed in a regional palinspastic framework, models of source rock deposition can be developed, and used to better predict timing and extent of deposition.
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Carboniferous Paleogeography of North-eastern Siberia
Authors V. Ershova, A. Khudoley and A. ProkopievThe study area is located on the northeastern margin of the Siberian Craton. The Carboniferous time was marked by extensive transgressions with widespread distribution of marine deposits throughout the study area. The Carboniferous deposits show transition from deep see basin environment through distal prodelta environments to prograding deltaic (delta front and delta plain) environment. One of the main questions for this region is a source area for Carboniferous deposits of North-East Siberia. We are presenting here a provenance pioneer study based on detrital zircon dating. All samples contain zircons with similar age populations, although relative abundance of each population varies. Zircons of Palaeoproterozic-Archean, Neoproterozoic and Devonian-Early Carboniferous ages are most widespread, whilst zircons of Cambro-Ordovician ages constitute an insignificant portion. Similarly, the Siberian Craton provenance must be rejected as a possible source area for Palaeozoic zircons in the studied samples, as felsic Palaeozoic magmatic rocks are also absent in the Siberian Craton basement. The only known potential provenance area with magmatic rocks comparable in age with the studied Palaeozoic zircon populations are the Altay-Sayan and/or Taimyr - Severnaya Zemlya fold and thrust belts
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Laptev Onshore to Offshore Relation
Authors B.C. Mouly and D. FrankeOur approach consists in 1. constraining the evolution of rifted shelf with the age of magnetic chrons in the Eurasia basin, and interpret a break-up unconformity that correlates in time with the emplacement of the oldest oceanic crust in the Eurasia Basin 2. Differentiate on seismic the sedimentation patterns from greenhouse conditions from those of icehouse conditions, as documented by the ACEX well drilled on Lomonossov Ridge. 3. Correlate nearshore structural cross sections, calibrated on deep wells with shallow water seismic data 4. Compare the basement structure prepared from magnetic records with the acoustic basement interpreted from seismic data 5. Calibrate older seismic data against newer, acquired with long-streamer, to better define the base of the rift infill and its relation to regional structural styles existing from Verkoyansk to Annabar.
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Model of Regional Tectonics and Hydrocarbon Potential Offshore Russia and Foreign Sectors of the Black Sea - Caspian Region
By B.V. SeninAnalysis of new geophysical data on the Black Sea – Caspian Region acquired since late 90-ties, partial reprocessing and reinterpretation of archival geophysical and geological results of oil and gas prospecting both offshore and on adjacent land areas, systematization and generalization of the entire dataset enabled the represented corrections of traditional views upon tectonics and hydrocarbon potential of the Caspian Sea, the Black Sea, the Sea of Azov, and adjacent terrain.
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Regional Seismoprospecting Works in Coastal Territory of Republic Dagestan and in a Shallow Zone Adjoining to it
Authors L.T. Guseinova and R.D. YusufovThe uplift of cretaceous reflecting horizons revealed earlier in a sea direction, has allowed to suggest presence of structures not defined earlier, located in a coastal zone which could be perspective objects for searches of hydrocarbonic raw materials. A neogene – upper cretaceous deposits are perspective here according to prospecting--production drilling. The second regional stage of inspection of southern Foothill Dagestan which has included inspection of a coastal and shoaly zone of the Dagestan part of Caspian sea was finished in 2007-2008. Newly interpreted received results of regional seismic operations, in inspecting the South Dagestan bow area, have allowed to specify a structural and tectonic construction on a neogene- upper cretaceous deposits, to substract in a coastal and shoaly zone 14 new structures perspective for searches of oil and gas and to give them a resource estimation
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Seismic Facies Model of the Lower Cretaceous Eastern Part of the Azov Sea
Authors G.M. Makanova and I.V. ShiryaevaОсновным этапом исследований являлось проведение сейсмофациального анализа. Использование методов сейсмостратиграфии позволило разработать седиментационную модель нижнемеловых отложений неизученной бурением акватории Азовского моря. Полученные результаты использованы для оценки перспектив газоносности выявленных антиклинальных структур.
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New Approach for Building a Tectonic Model of the Black Sea Depression
Authors A.V. Khortov, B.V. Senin, S.D. Kakaranza, N. Kaymakсi, E. Kozhuharov, I. Gabriel, M.I. Leonchik, N.V. Amelin, E.I. Petrov and B.W. HornВ работе представляются результаты новой серии региональных сейсмических профилей, пересекающих всю Черноморскую впадину и отработанных с использованием современных технических средств и технологий спустя 30 лет после проведения здесь первой серии подобных исследований. Полученные материалы позволяют по новому представить ряд аспектов геологического строения, тектоники, истории формирования впадины и её современной геодинамики.
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Reservoir Properties Forecasts in BS10-2+3 Layer Based on Different Geostatistical Inversion Techniques
Authors I.S. Tsybulkina, K.E. Filippova, P.G. Ponomarenko, V.M. Vingalov and S.V. LyagushevВопрос выбора наиболее достоверного метода прогноза коллекторских свойств является весьма сложным и актуальным. Поэтому на примере Северо-Конитлорского месторождения были оценены возможности прогноза коллекторских свойств пласта БС10-2+3 в условиях его значительной латеральной изменчивости и при малых толщинах коллекторов с использованием двух типов геостатистических инверсий, а именно: полнократного куба и частично-кратных сумм.
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AVA Stack Rotation as Fast Track Tool for Seismic Reservoir Characterization - A Case Study from a Pre-Caspian Basin
Authors A. Shestakov and A. JangirovA modified approach of AVA analysis is presented in this paper. It is AVO screening technology which combines AVO analysis and statistical rock physics study for gaining insight into the hydrocarbon reservoir.This workflow is time-efficient and allows for the analysis of large seismic volumes with limited or no well control.
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Biot Inversion of Microseismic Data for Permeability Estimation - A Feasibility Study
Authors R. Shigapov, A. Droujinine and B. KashtanThe estimation of poroelastic properties of reservoir rocks is a very important and topical problem. In this work we focused on the permeability estimation. Assuming that the input data were obtained during hydraulic fracturing experiments, our goal is to estimate the rock permeability using elastic full waveform inversion of microseismic data. We have done a set of numerical tests in order to study stability of the method to noise and velocity model errors.
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CRS Prestack Data Conditioning for Extending AVO Analysis to Low-fold and Low-quality Data Zones
Authors H. Trappe, G. Gierse, J. Pruessmann, G. Harms and H. VosbergThe Common-Reflection-Surface (CRS) method may improve seismic processing beyond imaging, e.g. in an enhanced Amplitude Versus Offset (AVO) analysis. Various applications have shown that the more realistic subsurface assumptions, and the increased fold of the CRS imaging allow to extend AVO analysis into noise zones and to deep targets with low signal quality. Extreme fluctuations of AVO parameters are removed, and AVO anomalies are enhanced. The CRS method assumes subsurface reflector elements with dip and curvature, which implies large-fold stacking surfaces extending both across offset, and across neighboring CMP locations. The extension across neighboring CMPs defines a CRS gather at the central CMP location, comprising data from a multitude of traces. The CRS moveout correction compensates for the local dip across these neighboring CMPs, thus contrasting to conventional AVO super-gathers based on NMO correction that collect dipping events horizontally at varying phase. The presented case studies show that CRS-AVO attribute stacks are produced with a much higher signal-to-noise ratio from CRS gathers than from CMP gathers in conventional AVO. The CRS-AVO attribute sections clearly distinguish anomalies at known or expected gas-bearing reservoirs.
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Prestack Inversion and Probabilistic Lithofluid Classification - A Case Study from the Caspian Sea
Authors S. Klarner, N. Buxton and S. BenkoThe Caspian Sea is currently one of the focus areas for exploration and production in the FSU. Logistically a challenge (large areas with very shallow water) and ecologically sensitive (endemic flora and fauna), it demands operators to develop a sustainable approach to hydrocarbon development in the region. In that context, a better understanding of the subsurface helps to optimize drilling activity as one of the factors having a huge environmental impact. The AVO inversion and probabilistic lithofluid classification approach presented in the current paper, is one of the technologies applied to improve the subsurface understanding of the area in order to optimize the future field development. The workflow includes seismic data improvement by reservoir oriented processing procedures, a comprehensive rock physics analysis on well data, simultaneous inversion of angle stacks, crossplot analysis of inversion results and probabilistic lithofacies classification in the AI-Vp/Vs domain using the established depth dependent rock physics trend. First experience of using a probabilistic approach to quantify the reservoir properties shows that potentially even pore fluids can be estimated from seismic data.
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From Rock Physics Study through Inversion to Seismic Litho/fluid Prediction - A Case Study from Precaspian Basin
By A JangirovIn this paper a new approach is proposed for seismic reservoir characterisation. The workflow shows how rock property trends can be derived, compared with seismic amplitudes and used in prediction of litho/fluid content based on observed seismic amplitudes. The workflow is supported by case study using the data from Precaspian basin.
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Choosing Seismic Dataset with Application of Deterministic Full Stack Inversion
Authors K.E. Filippova, A.A. Kozhenkov, J.L. Debrouх and D.V. IsakovIt is common that several seismic datasets are available on the same project as a result of reprocessing. Different companies may reprocess the same datasets using various technologies and different processing sequence and interpretation team have to choose the most suitable volume for interpretation and reservoir properties forecast. Sometimes it is a really difficult choice.
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Seismic Inversion Potential for Carbonate Reservoir Modeling, as Exemplified by Samara Region
Authors I.A. Babenko, T.V. Nekrasova, V. Sheppard and I. GontarenkoThe paper describes the use of seismic inversion for the purpose of prediction and delineation of oil-saturated reservoir areal Samara region fields.
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SGS-based Stochastic Inversion Workflow for Clastic Thin Layer Properties Recovery in Carbonate Medium
More LessThe problem of recovery clastic layer properties in carbonate medium was solved with Sequential Gaussian Simulation (SGS)-based stochastic inversion. Stability analysis of this workflow results was presented. The estimate of identification possibility low-impedance object in high-impedance medium. Method of assessing sufficient for practice multiple realizations of stochastic inversion was proposed.
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Geology as the Main Factor in Determining the Technology Required in Seismic Inversion and Interpretation
Authors M. Romanenko, D. Kutcheryavenko, S. Iliin, A. Dubok and D. EmeliyanovВ условиях активного развития и применения методик сейсмической инверсии ключом к успешному решению задач прогноза является не столько алгоритм, сколько понимание особенностей геологического строения изучаемых объектов. В рамках работы над одним из производственных проектов мы столкнулись с очень интересным и нестандартным для Западной Сибири геологическим строением изучаемой толщи, которое поставило много нетривиальных задач для акустической и синхронной инверсии. На нескольких примерах с различных этапов проекта показано, каким образом понимание особенностей геологического строения района и целевого интервала может повлиять на методику расчета и интерпретации кубов упругих параметров. В заключении работы даны практические рекомендации, которые могут быть полезны, специалистам работающим в области интерпретации данных сейсморазведки.
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The Detailed Facial Model of Complex Clastic Reservoir Based on Geostatistical Inversion Results
Authors K.E. Filippova, P.G. Ponomarenko, I.S. Tsybulkina, V.M. Vingalov and S.V. LyagushevРассмотрены возможности использования геостатистической сейсмической инверсии для уточнение строения залежи и выделения зон выклинивания и литофациальных изменений продуктивного интервала. Данная методология может быть успешна применена для уточнения строения пластов месторождений Западно-Сибирской нефтегазоносной провинции.
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Electroacoustic Logging and Joule Heating
Authors B. Plyushchenkov and A. NikitinIt is well known that electromagnetic field excites acoustic wave in a porous elastic medium saturated with fluid electrolyte due to electrokinetic conversion effect. Pride's equations describing this process are written in isothermal approximation. Update of these equations, which allows including influence of Joule heating on acoustic waves propagation into account, is proposed here. This update includes terms describing the initiation of additional acoustic waves excited by thermoelastic stresses and the heat conduction equation with right side defined by Joule heating. Results of numerical modelling of several problems of propagation of acoustic waves excited by an electric field source with and without consideration of Joule heating effect in their statements are presented. From these results, it follows that influence of Joule heating should be taken into account at the numerical simulation of electro-acoustic logging and at the interpretation of its log data.
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Deep Fracture Imaging Using Dipole Acoustic Data
Authors A.O. Bolshakov, D.J. Patterson and C. LanCharacterizing acoustic fractures in reservoir rocks is important because these fractures provide critical conduits for hydrocarbon production from the reservoir into the wellbore. The standard method uses shallow borehole imaging services, both acoustic and resistivity, which image the intersection of the fractures at the borehole wall. Cross-dipole technology has extended the depth of evaluation some 2 to 4 ft around the borehole by measuring the fracture-induced azimuthal shear-wave anisotropy. A recently developed shear-wave reflection imaging technique provides a method for fracture characterization in a much larger volume around the borehole with a radial extent of approximately 70 ft. This technique uses a dipole acoustic tool to generate shear waves that radiate away from the borehole and strike a fracture surface. The tool also records the shear reflection from the fracture. The shear-wave reflection, particularly the SH waves polarizing parallel to the fracture surface, is especially sensitive to open fractures, enabling the fractures to be imaged using this dipole-shear reflection data. We use field examples to demonstrate the effectiveness of this shear-wave imaging technology that maps fractures up to 70 ft away and even detects fractures that do not intercept the borehole.
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Inversion of 1D VES Data Using New a Technique Called Recursive Ant Colony Optimization (RACO)
Authors Y. Arora, D.K. Gupta, J.P. Gupta and U.K. SinghIn this abstract a new algorithm is proposed named Recursive Ant Colony Optimization (RACO) for inversion of 1D VES data. RACO is derived from a more general global technique known as Ant Colony Optimization (ACO). In this new algorithm, results obtained from first run (first depth) are fed to next run (next depth) which is called recursion. The level of recursion of the process is defined by the term “depth” and hence directly affects the accuracy of the results. Advantage of using the recursion in this algorithm is that the convergence of the problem becomes exponential which is linear in ACO thus this approach become different from its general form. This code is written in C++ which makes it more time efficient. To make this algorithm stable it is tested on synthetic data of 3 layers earth model and 5 layers earth model. Both of the examples chosen are difficult to delineate due to presence of high resistive layers (K-type and HKH-type curve). Then this method applied to field data from Satkui and Tangasol region of Midnapur district of West Bengal, India. Results obtained after completion of the inversion process are found to be in agreement with the available results.
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The System of Adaptive Well Log Data Interpretation in Geological Modeling
Authors A.N. Petrov, D.A. Kozhevnikov, K.V. Kovalenko and I.S. DeshenenkovWide spread application of 3D geological modeling, oil and gas field development practices resulted in substantiation of the necessity for transition from the traditional concept of “absolute pore volume” to the concept of “effective pore volume”. This could be achieved with the geophysical and logging data algorithms interpretation and procedures system directed to the determination of reservoirs dynamic characteristics with high vertical resolution united with principles of adaptability and petrophysical invariance of reservoirs. Adaptive petrophysical models make possible the quantitative estimation of effective porosity and effective/phase permeability. Formation parameters, which characterize the content of bound water in the matrix and cement, maximum possible total porosity and effective porosity, relations between effective porosity and effective permeability are estimated according to outcomes of petrophysical modeling. Effective porosity is calculated with the standard logs data interpretation. The distribution of reservoir properties in three-dimensional space is carried out with geostatistical simulation techniques. Application of effective porosity to prediction of relative permeability and capillary pressures with log data was realized as an important task for field development design. The test of the proposed technology is conducted on a large number of wells worldwide. Formations consist of clastic fine-grained sandstones with complex cement mineral composition.
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Determination of Capillary Pressures and Relative Permeabilities with Well Logging Data
Authors A. Petrov, D.A. Kozhevnikov, K.V. Kovalenko and I.S. DeshenenkovIn oilfields development process it is necessary to determine attitude of fluidal contacts performedby the deposit area on the base of geological, geophysical and petrophysical data integration add‐in advanced well logging techniques. We propose new capillary model, controlled by a single parameter that is closely related to permeability. Developed model allows more accurate determination of the displaced fluid share at a given capillary pressure during drainage in comparison with analogues. Saturation estimation algorithm based on proposed model was proposed. The advantage of the algorithm is the possibility of hydrocarbon saturation reliable prediction in case of resistivity logging is non-informative due to the low vertical resolution in the layers of low width and anisotropic reservoirs. In practice, Burdine and Brooks-Corey model as the most common approximations of relative permeability curves are used. But these models describe laboratory core measurements data poor in low relative permeability area. New analytical approximations for more detailed and accurate description of relative permeability curves was obtained. Description results show that proposed model has better accuracy in comparison with known analogues. Relative permeabilities can be used for prediction of the brine share in production volume with Leverett function and have great practical importance for field development design.
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Velocity Detection by Duplex Wave Migration
Authors N. Marmalevskyi, S. Gorbachev, Z. Gornyak, G. Dubrova and B. LinkThe sensitivity of the duplex wave migration to the wave propagation velocities is considered. On the field 3D data, the evaluation criteria for detection of correct velocity assignment are shown for the duplex wave migration based on the Kirchhoff integral The opportunities of definition of velocity in thin layers, which thickness is less than length of a seismic wave and complicated with permeable fractures corridors are considered.
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Velocity-less Pre-stack Time Migration in Application to Hard Rock Environments
Authors K. Tertyshnikov, A. Bóna, R. Pevzner and B. GurevichReflection seismic techniques have a number of limitations to get suitable images in hard rock environment. Many seismic migration algorithms need to know the values of propagation velocity of acoustic waves. In sedimentary basins, where layers are usually continuous reflectors, that information could be obtained directly from acquired data, but there are many steeply dips and lack of the horizontal boundaries in hard rock media. In this way, the estimation of velocity model is a really difficult task. Here we describe the velocity-less pre-stack time migration in application to hard rock conditions and demonstrate the results on synthetic data.
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Non-linear Analysis of Low-frequency Microseismic Background
Authors S.B. Turuntaev and O.Y. MelchaevaLow frequency seismic data were analyzed with the help of non-linear Grassberger-Procaccia method. Two data sets were considered: microseismic background inside and outside gas field (“passive” method) and the microseismic background recorded before and after vibrations over an oil field with complicated unknown boundaries (“active” method). It was found, that an application of non-linear methods has to be done with caution. Only the analysis of the records containing pulses allowed to distinct the microseismic background inside the gas field from the background outside the field. The analysis of the records obtained after the vibrator works showed an appearance of deterministic component in the microseismic background after the vibrations at several studied points. Two wells were drilled in proposed points, and the both were successful.
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Incorporation of Multiples for Migration Velocity Analysis with VSP Data
Authors D.A. Nasyrov, D.A. Kiyashchenko, Y.V. Kiselev, B.M. Kashtan and I.V. AbakumovWe demonstrate the original method for the migration velocity analysis with VSP data. The method is based on the use of surface-related multiples jointly with the primary reflected data for the VSP imaging. Velocity updates are carried out by matching the images obtained by using different types of waves. To do it automatically we introduce a cross-correlation type objective function and develop a maximization algorithm based on the adjoint-state method. We show that maximization of the cross-correlation of the images built on different types of waves allows to retrieve the velocity parameters. At the same time the refinement of the velocity model could lead to significant improvements of the seismic images.
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Improved Depth Imaging by CRS Signal Enhancement in Input Shot Gathers
Authors G. Gierse, G. Eisenberg-Klein, H. Trappe, J. Pruessmann and M. ZehnderNoise suppression and signal enhancement prior to prestack depth migration (PreSDM) may significantly increase the resolution of the depth image, and the effectiveness of the PreSDM workflow. The Common-Reflection-Surface (CRS) technique was previously used for this enhancement of seismic prestack data, providing so-called CRS gathers with regularized CMP and offset coverage, and with a strong noise suppression. These CRS gathers considerably improved the depth image in Kirchhoff PreSDM but were not suited for shot-based PreSDM algorithms. This case study now presents a straightforward way to produce geometry-preserving CRS gathers that similarly increase the signal-to-noise ratio. In a first implementation, CRS prestack data interpolation is performed at the existing trace locations providing a straightforward and automatic preservation of the original shot geometry. Application to 3D seismic land data demonstrates the improved signal-to-noise ratio and resolution both in the geometry-preserving CRS shot gathers, and in the corresponding QC stack. As in the Kirchhoff migration of regularized CRS gathers, such enhancements are expected for Reverse Time Migration of CRS shot gathers as well.
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Band-limited Ray-tracing through Rugose Interfaces
Authors C.E. Yarman, X. Cheng, D. Nichols, K. Osypov and M.I. ProtasovStandard ray-tracing is a very efficient way of approximating wave propagation for small wavelengths, or, equivalently, high frequencies. Furthermore, it is still valid when the medium parameters and the wavefields are smooth on the scalelength of the width of the Fresnel volume (Kravtsov and Orlov, 1990). Standard ray-tracing validity conditions break down in the vicinity of an interface when there is high contrast between the two sides of the interface and/or the interface has a complex structure. In this study, we present a new band-limited ray-tracing method that aims to overcome some of the limitations of standard high-frequency ray tracing in complex velocity models that contain complex interfaces. With a modest increase in computational cost, the method presented captures the wave kinematics that are comparable to finite-difference wave propagation with higher fidelity while staying within the ray-tracing framework, without requiring processing or alteration to the original model.
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3D Velocity Model Building Based on Diffractions
Authors S. Dell and D. GajewskiDiffracted events are of great importance in the seismic processing because they allow to identify the presence of small heterogeneities, truncations, faults. However, to reliable interpret such subsurface features caused by diffractions, the letter ones should be properly imaged. An inherent part of the imaging is therefore a migration velocity analysis which should be tuned to diffractions. Moreover, imaging of diffractions is inherently a 3-D problem. In real geological environments one can not expect diffractors to be located below 2-D profiles. The 3-D effects of diffractors located transverse to the profile line leads to a smeared and less reliable diffraction images. We present a method for 3-D velocity analysis based on diffracted events. We perform migration velocity analysis by evaluating the semblance norm along diffraction traveltimes both in the depth and time domain. Finally, we perform Kirchhoff type of poststack migration with estimated velocities to validate the presented velocity analysis.
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Interval Anisotropic Parameter Estimation from Walkaway and 3D VSP Data
By E. BliasThe purpose of this paper is to present a new method for interval VTI anisotropic parameter estimation above and within VSP array. Above receiver array, the method utilizes duplex downgoing multiples (multiples with two reflections: from the boundary and free surface) for estimation of a layered depth velocity model above the borehole receiver array. A three-term NMO approximation function is used to estimate NMO velocity and a non-hyperbolic parameter. Dix-type inversion is applied to the three parameters to invert them to interval Thomsen anisotropic parameters ε, δ above the receivers. Velocity gradient influence is analyzed analytically. It is shown that in many cases we can neglect its influence on anisotropy estimates. Within the VSP receiver array, the method creates a virtual horizontal reflector at each receiver depth by calculating reflected traveltimes as a sum of two first breaks from the symmetrical source points. For 3D or multi-azimuthal walkaway survey, this approach is generalized for a model with horizontal homogeneous orthorhombic layers.
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The Detalization of Difficult Constructed Objects on the Base of Seismic Processing Interpretation
By A.A. NikitinThe article deals with new seismic attributes and processing technologies that provide difficult constructed objects with the forecast of hydrocarbon identification.
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Complexing of the Reflected and Refracted Waves in the Processing and Interpretation of Multichannel Marine Seismic Data
More LessRefracted waves usually removed for processing and interpretation of the marine seismic data. However, they can provide additional information about the structure of the section and the presence of local low velocity zone. In this work the seismic section of the refracted waves along the profile 5-AR (East Siberian Sea) was constructed. With help the refracted and reflected waves was detected the low-velocity anomaly due to hydrocarbon deposit. Made refinement of the structure of the upper part of the lifting of Wrangel. Showed the advantage of using refracted waves for processing of the multichannel marine seismic data. Proposed to use the refracted wave in the processing and interpretation of marine seismic data. Showed the original method of determining the low-velocity anomalies, wich located in the sedimentary rocks.
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Advanced Modern Technologies for Old 3D Seismic Data Reprocessing - Case Study, Kharyaga Field
New seismic processing technologies can help extract additional useful information even if they are used with old seismic data. Seismic acquisition was performed in 2001 with the vibroseis and slanted NonWAZ acquisition system resulting in original bin size of 12.5x25m and nominal fold of 40. New advanced technologies were applied to get get better quality seismic imaging from full data reprocessing sequence. 5D seismic data regularization and interpolation to a denser shot and receiver grid were done to make possible the implementation of WAZ processing sequence. Data was, in fact, mapped to a new perfectly regular survey on bin grid 12.5x12.5m, which had higher fold of 160 and more regular offset and azimuth distribution. WAZ approach made possible COV- processing, azimuthal velocity analysis and 3D Radon using. The main features of our PSDM processing included separate PSDM runs for different azimuth sectors, PSDM from floating datum with shallow velocity derived from refraction statics model and using of non-linear hybrid tomography. Improvements in seismic data resolution, small magnitude faults imaging and correlation with well data are observed as the result of advanced technologies applying.
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Petroleum Systems in the Okhotsk Sea Region
More LessResearch targets are the largest basins of the Okhotsk Sea region (Northern and Western Sakhalin, Northern Okhotsk and Western Kamchatka). The data on composition, petrophysical and geochemical properties of borehole sections’ rocks, seismic survey (CDP technique) were analyzed. Particular attention was paid to the tectonic and sequence stratigraphic subdivision of covers, identifying sediment structure of petroleum systems and relationships between its components: oil source suits, reservoirs and cap rocks. Three groups of petroleum systems were distinguished: Upper Cretaceous, Lower Cenozoic (Pre-Upper-Oligocene) and Upper Cenozoic (Upper Oligocene-Pliocene). The Upper Cretaceous petroleum systems are the top of the folded (mostly destroyed) basement. The Lower Cenozoic petroleum systems are represented by the rift system with complex sediment structure and random pattern distribution of low permeable reservoirs. The Upper Cenozoic petroleum systems pose the highest petroleum potential. This petroleum systems are characterized by asymmetry associated with unilateral progradation of sequences towards deep-sea trenches. Reservoirs prevail in the proximal and central parts of the sequences; siliceous-argillaceous strata with high oil generation potential are predominated in the distal parts of the sequences.
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Making Seismic Data as CSEM Data through the Bäcklund Transform
Authors J.M. Virieux, R. Brossier, S. Garambois, S. Operto and A. RibodettiBäcklund transform is applied to a seismogram in order to construct a new signal where the time is transformed in a pseudo‐time the square of its dimension is expressed in seconds. The Bäcklund transform links partial differential equations related to wave propagation to partial differential equations related to diffusion. Potential applications have been performed previously from magnetotelluric data to pseudo‐seismic signals by using the inverse of the Bäcklund transform. This transform could be applied to the seismic signal through real computations. Therefore, we propose to transform seismic data into pseudo‐CSEM signals for possible applications of these diffusive signals as the initial stage of the full waveform inversion of seismic data.
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Quantitative Analysis of Seismic Uncertainty
Authors K. Osypov, D. Nichols, C.E. Yarman, F. Qiao, M. Woodward, N. Ivanova, Y. Yang, R. Bachrach and Y. LiuUncertainty is inherent in E&P business and understanding uncertainty enables mitigation of E&P risks. Therefore, quantification of uncertainty is essential in decision-making and managing uncertainty generates business value. One of the most critical parameters for reserves uncertainty and well placement is positioning of interpreted geological structure in the depth domain. Even with our best efforts to combine all available data there is still ambiguity in our models, caused by the inherent non-uniqueness of the seismic experiment. The result is uncertainty in the true positions of events in our images. These uncertainties can lead to exploration risk (e.g. trap failure), drilling risk (e.g. dry wells), and volumetric uncertainties. Whilst the underlying ambiguity can never be fully eradicated, a quantified measure of these uncertainties provides deeper understanding of the risks and leads to more informed decision making. We introduced a workflow for the statistical analysis of structural uncertainty associated with the ambiguity of tomographic velocity model building. Our method provides a quantitative way to determine the trap risk. Here we present this seismic-driven uncertainty analysis method and a case study for its application in the Gulf of Mexico.
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Geometric Analysis of Seismic Imaging Operators and Continuation Operators
By A.A. DuchkovIn this paper we provide an overview of some concepts and results by S.V.Goldin in the field of geometric theory of seismic imaging. Then we present some recent results on velocity continuation of seismic images developing his ideas. We will provide a few examples of Hamiltonians describing propagation of singularities during a velocity continuation of seismic (extended) images and propagation of isochrones in the framework of constant-offset migration.
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SVD for Macro-velocity Model Reconstruction by Full-waveform Inversion
Authors I. Silvestrov, D. Neklyudov and V.A. TcheverdaThe key element of seismic processing workflow in areas with complex geology is a depth velocity model building. A full-waveform inversion technique is considered currently both by academia and industry as a potential solution of the problem. The resolution and sensitivity of the method can be studied reliably by considering the Frechet derivative of the original nonlinear forward map. Examining its singular value decomposition provides the detailed information about the inverse problem, particularly about the low-frequency velocity model reconstruction ability. In the current work we present such study considering a look-ahead VSP experiment in which the velocity model below the borehole bottom is inverted. Using truncated SVD we show that success of the inversion strongly depends on the available low frequencies in the data and on the noise level. For the particular model we find the acceptable noise level and the required frequency content of the data needed for reliable inversion of the smooth velocity model. The presented approach may be adapted to any particular model and acquisition system and may be used as a tool for prediction the solution properties prior to any inversion procedure and for producing the requirements to the data which are necessary for successful inversion.
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Reliable Interval Q-factor Estimation from VSP Data
By E. BliasThe purpose of this paper is to present a new method for interval Q-factor estimate using near-offset VSP data. This method is based on objective function minimization of the difference between actual layered Q estimates and those calculated through interval Qs. To calculate interval Qs, we use Q estimates for all receiver pairs that provide reasonable Q values. To estimate layered Q between two receiver levels, we utilize an exponent approach which provides more accurate Q values than the spectral ratio method. Application of this method to real data demonstrates good correspondence between Q estimates and vertical velocity changes.
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Application of Perturbation Theory to TTI Media
Authors A. Stovas, T. Alkhalifah and P. GolikovUsing an elliptical tilted TI medium as a background we apply the perturbation method to compute both the eikonal and the slowness surface equations in a general TTI medium.
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