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7th EAGE Saint Petersburg International Conference and Exhibition
- Conference date: 11 Apr 2016 - 14 Apr 2016
- Location: Saint Petersburg, Russia
- ISBN: 978-94-6282-179-8
- Published: 11 April 2016
101 - 198 of 198 results
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Uncertainty Quantification in Fractured Reservoirs Based on Outcrop Modelling from Northeast Brazil
Authors A. Bakay, V. Demyanov and D. ArnoldThis work is aimed at uncertainty quantification of flow performance in fractured reservoirs. The study demonstrates how outcrop data on fracture distribution are integrated into uncertainty quantification workflow. It includes eliciting statistics from the outcrop data to generate ensemble of discreet fracture networks (DFNs), DFNs upscaling into permeability grids, clustering of models according to permeability patterns, choice of training images for the cluster scenarios and generation of multiple realisations, flow simulation to come up with the spread of uncertainty in the recovery performance. The influence of fracture intensity and orientation on recovery efficiency was quantified. Uncertainty was represented by multiple sets of realisations based on training images. The workflow created is applicable to any fractured reservoir studies. The data for the case study is from five outcrops in Jandaira formation from NE Brazil, Potiguar Basin was mapped by Delft University. Results of simulation are of significant importance for southern Brazil hydrocarbon fields which have reserves in similar carbonate formations. This research was focused on geometric properties of fracture networks; further investigation of physical properties of fractures and integration with well and seismic data is essential for accurate properties prediction of fields from southern Brazil.
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Airborne Electromagnetic Near Surface Investigations – Fort McMurray, Alberta
Authors A. Prikhodko, T. Eadie and C. IzarraOnshore Oil and Gas geophysical exploration programs lack a timely, cost-effective solution to map the first 50 to 100m of geology. Filling in this gap of knowledge by accurately mapping the near-surface geology is beneficial to reduce risks associated with the exploration and production of Oil and Gas. Conventional seismics cannot resolve it due to wave energy dispersion in the top unconsolidated sediments and the use of large source-receiver offsets. In fact, the first decametres of geology usually comprises of an irregular and laterally-varying low velocity zone or localized structural complexity that poses tremendous challenge during seismic processing by significantly deteriorating the signal-to-noise ratio and inhibiting the proper imaging of deep seated geological targets. Through continuous innovation, airborne time-domain electromagnetic systems have expanded their ability to map geology from the surface to depths of hundreds of metres. With the introduction of Full Waveform technology, VTEM pushes the limits of airborne TDEM’s ability to map near-surface geological features. This paper highlights VTEM’s ability to accurately map the near-surface geology, using a dataset collected near Fort McMurray, Alberta, in the Aspen Block for Imperial Oil.
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Statistical Approach to Seismic Deghosting
Authors M.S. Denisov and A.E. FirsovGhost reflections occur in the process of seismic data recording. The ghost wave is a noise event and should be eliminated while data processing. A method to attenuate the ghost reflection is presented. It allows both the source- and receiver- side deghosting. An estimator of the reflection coefficient and ghost time delay is incorporated into the optimization scheme.
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Integration of the Reflected and Diffracted Waves to Increase the Reliability of Predict Fractured-Porous Reservoirs
Authors A.N. Inozemtsev and A.S. SorokinThe traditional wide-azimuth seismic surveys with small offsets provide irregular depth illumination of the object and from the specular-reflected waves and by the use of diffracted waves, making it very difficult to share when their drill oil and gas reservoirs. Modern full-azimuth survey with large offsets (up to 5-10 km and more) with high expansion and a relatively uniform distribution of the deletions provide unique opportunities for sharing the information obtained from the mirror-reflected and diffracted waves at their integral interpretation for the study and mapping of fractured -porous collectors. The report shows the possibilities of interconnecting the mirror-reflected and diffracted waves according to the full-azimuth seismic data to improve the reliability and detail mapping of fractured-porous hydrocarbon reservoirs. The examples of the effectiveness of this technology in certain fields of the CIS
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Depth Velocity Model Building with Compensation of Near Surface Heterogeneities
Authors E.L. Svistova, A.A. Shevchenko, E.K. Korolev and A.E. KorolevThe central point of the modern seismic technology is the velocity model construction and obtaining the trustful depth image. There are different approaches and ways of compensation of subsurface heterogeneities. However, the problem includes not only compensation of the influence of the complex subsurface structure but also for the influence of the elevation surface. In case of complex elevation that varies greatly it is important to have a reliable technique of compensation for its influence on kinematical parameters of seismic data. The new technique of the subsurface heterogeneities compensation in seismic data is offered in this paper. The method is based on the refracted wave modelling and tomography. It allows involving into the correction the surface geometry variations.
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Low Frequency Seismic Spectrum Restoration in Case of Complex Seismogeological Environment
More LessAuthor of this paperwork describes a new technology of seismic signal restoration in low frequency band in case of complex seismogeological environment when traditional methods of compensation seismic spectrum lack in low frequencies are not implemented. Technology based on geological environment non-linear effects analysis of conventional seismic band data. Low frequency data restoration algorithm based on wavefield analysis independently from horizons structure as an alternative of well logs interpolation procedure.
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Marine Seismic Data Preprocessing for the Field Acquisition Distortions Compensation
Authors A.A. Shevchenko, A.E. Bronskiy, B.S. Esinov, A.V. Grobushkin, A.E. Korolev and S.A. PolyanovTime Lapse seismic survey is based on the precisely data observation. All differences in observation system have to be removing from the data in the processing stage. For the marine observation most essential data distortion caused by the different trajectory and motion speed of the sea boat. Dual surveys binning are needed for the similar position traces take into account in processing and data CDP staking. Our goal is to compare different ways for the data preprocessing and motion data distortions compensation.
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Complete Wavefield Imaging for Lithology and Fluid Prediction in the Barents Sea
Authors G. Rønholt, Ø. Korsmo, S. Naumann, S. Marinets, E. Brenne and M.F. AbbasiIn the shallow water environment found in parts of the Barents Sea, conventional imaging struggles to provide good imaging of the near surface. This is due to the lack of near offsets (angles) in typical marine seismic data, caused by the large minimum distance between the source and receivers. Here, we present a method that uses separated (up- and down-going) wavefields provided by dual-sensor streamer technology to construct images and image gathers that span a complete range of incidence angles. In this method, each receiver is also used as a virtual source, hence providing a dataset that has complete coverage of zero- and near-offsets everywhere under the seismic spread. In particular, this provides near-angles for shallow targets that are not sampled by primaries, enabling amplitude versus angle (AVA) analysis to be carried out. The AVA results can be used as a direct hydrocarbon
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Filtering of seismograms, for and against
Authors V.M. Vingalov, S.V. Lagushov, A.A. Arjilowsky and R.V. GritsenkoThere are lot of noise waves and background noise suppression procedures common in seismic CDP data processes these days. Many of these procedures are necessary, like surface waves, ringing wave and post-stack data noise suppression. But there are also a lot of well-spread unnecessary procedures, like multichannel filters for additional suppression of seismic noise and linear disturbances in seismic record. This report compares results of common noise suppression with distortion of amplitude characteristics of a seismic record caused by additional filtration exemplified in 3D data of one of West Siberian fields
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Geological Medium Induced Polarization as an Electromagnetic Phenomenon
Authors F.M. Kamenetsky, G.M. Trigubovich and A.V. ChernyshevIs the electromagnetic field theory that is borrowed from physics and based on the assumption of «pure substance» properties (independent of time and frequency), which is still widely used in geophysics, adequate to a real geological medium? It is shown that a more general phenomenological theory of the electromagnetic field is required, and the theory that is still in use is the simplest approximation of such a general theory. Inversion of data for a polarized medium without accounting for polarization leads to significant errors even when the presence of a polarization part in the signal is not identified. The induction and polarization fields are additive in the near zone (late stage) and exhibit different dependences on the size and configuration of the transmitter-receiver assembly. These features make it possible to separate these fields using the results of measurements acquired with assemblies of various sizes and/or configurations. These possibilities are illustrated by using the results of experimental studies.
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Some Results of Magnetic and Geochemical Work in Order to Search for Hydrocarbons (South of West Siberia)
Authors A.N. Orekhov and I.S. SobolevThe results of the use of complex non-seismic methods for the study of hydrocarbon deposits (including non-traditional) in the south of Western Siberia. As the complex itself, and methodological approaches to its field implementation and interpretation of the data we were formulated based on analysis of generalized physical-geological model of the object searches. Are some examples of field work performed.
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Geological Interpretation of MT Data in Combination with GIS Data and Seismic Surveys in Caspian Depression in Kazakhstan
Authors G.K. Umirova, S.A. Istekova and I.N. ModinOn the basis of processing and interpretation of data MTS (magnetotelluric sounding) the digital geoelectric model of the Karaton-Sarkamys block located in the southern Kazakhstan part of Caspian Depression is created. Geoelectric cuts and structural cards are constructed on various geoelectric horizons. Possibility of effective application of MT-sounding in a complex with data of seismic exploration and well logging for receiving additional information on lithologic and collection properties of oil and gas complexes of the area of researches is shown
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Wavefield Transformation of Transient Electromagnetic Induction Soundings Data
Authors G.A. Gretskov, M.I. Epov and E.Y. AntonovThe report is devoted to the development of the algorithms and programs to perform wavefield transformation (Q-transform) of quasi-stationary TEM responses. Two different ways of implemetation of Q-transform are shown, first is based on singular value decomposition and latter - on Tikhonov regularization method. Results of different Q-transformations for horizontally-layered, polarized and quasi-3D geoelectrical models are provided.
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Induction Component Separation from TEM Data: Theory and Experiments
Authors F. Kamenetsky, G. Trigubovich, A. Chernyshev and A. KuklinInduction and polarization fields are additive in the near-zone of the transmitter and its dependence from dimension and/or configuration of transmitter-receiver system is different. This allow to separate induction and polarization fields using the results of transient soundings with different transmitter-receiver system. The examples of induction and polarization fields separation in polymetallic ores exploration are introduced.
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Background and Results of Adaptive Tem at Geoelectric Forecast in Eastern Siberia
Authors A.A. Belaya, G.M. Trigubovich, A.V. Chernyshev, N.V. Simankovich and E.N. MakhnachIn conditions of high contrast inhomogeneous upper part of the section when using TEM to obtain a reliable forecast for the target horizon, the reliable results can be achieved with areal-profile surveying system. It allows to consider the influence of heterogeneity of the host geological medium very correct and sufficiently complete. it is reasonable to use an adaptive variant of a distributed surveying system when conducting ordinary combined CDP and TEM survey on a regional profiles. For this purpose we developed a special procedure for estimating the dimension of the medium while doing research in the field. It also allows to control the "side" effects of objects in upper part of the section and take them into account when predicting the target horizons. The paper discusses the results of the adaptive TEM survey on the example of the geophysical survey at Chaykinskaya area. Interpretation errors, caused by insufficiently dense surveying system, have been demonstrated.
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Some Aspects of Research of a Natural Pulse Electromagnetic Field of Earth
Authors M.E. Dolgy and S.G. KataevThere is a set of the processes leading to emergence of a natural pulse electromagnetic field of Earth. Analysis of these signals are able to afford to gain an impression about the course of these or those processes. The main difficulty consists that sensors accept a total signal and to allocate from it a contribution of concrete process – extraordinary complex problem. The solution of this problem demands to be able to solve the following problem: to find information signs of concrete process in a signal taking into account its localization in space, intensity and time of action. We offer the approach including along with the analysis of time series of signals and research of the general thermodynamic model. The main goal – to carry out selection of deposits from various sources on the basis of transition from signal parameters (amplitude and number of impulses) to a "energy" scale. Introduction of a energy scale of a signal gives the chance to compare with each other the weight of various processes in a total signal. In work some primary results of this approach are presented. In particular, correlation between moisture content of a near-surface layer and intensity of the measured signal is shown.
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Design and Construction of a High Pressure and High Temperature Apparatus for Measuring Rock Thermal Conductivity
Authors A. Aryanzadeh, S.M. Alavi, A. Soleymanzadeh and M. YousefiSeveral thermal processes have been applied to enhance heavy oil reservoirs recovery. Despite the differences, all the methods are similar in developing a high temperature fluid front in porous media which will travel forward by conduction and convection mechanisms. Therefore it is essential to know thermal conductivity of rocks at reservoir condition in order to improve the results of modeling heat transfer through the formation. Several methods have been proposed to measure rock thermal conductivity. They can be categorized as transient and steady state. Although transient method is faster, the results are representative of only a few millimeters around the probe. Steady state method is more reliable and the results could be absolute or comparative, but it is time consuming and some operational difficulties are also involved. In this work, an altered steady state apparatus which overcomes the obstacles in other devices, has been designed and constructed for measuring rock thermal conductivity. Current devices have serious problems on simulating reservoir thermobaric conditions and desired fluid saturations. The new apparatus works at reservoir conditions and investigate the effect of different fluids saturation. It also reduces the effect of significant heat loss, during the long period of steady state method.
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Using the Profilograf in the Study of Thin-Layers Sections of Sedimentary Rocks
By M.Y. ZubkovTo study the thin-layers cross-sections of sedimentary rocks is proposed to use a method mikroprofilirovaning accurately allocate different lithological types of rocks in the composition of core samples and carry out the assessment of linear geological reserves in the investigated with its help intervals.
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Fluid Substitution Problem for Thermal Conductivity of Hydrocarbon Reservoirs Based on Rock Physics Methods
Authors T.R. Yalaev, I.O. Bayuk and E.Y. PopovThermal conductivity of rocks is used in different specialized area of prospecting geophysics. This is a key parameter of basin modelling, it is used while developing of enhanced oil recovery (EOR) methods. Several experimental methods exist to measure thermal conductivity: optical scanning technique, TPS etc. However it is a bit technical challenge to make measurements of rock saturated with high viscous fluid. Sometimes in case of weak consolidated rock it is impossible to keep a sample while saturation. This forces us to solve the fluid substitution problem for this thermal property. In this study we develop EMT-based models of carbonate and terrigenuos rocks and apply them to solve the fluid substitution problem. Specifically, we predict the thermal conductivity of oil-saturated rocks using data on thermal conductivity obtained for dry and water-saturated rocks. The predicted values are tested on experimental data obtained with the optical scanning method. We compare our results with other well known theoretical approaches (Lichtenecker and Roy-Adler formulae).
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Fracturing Evaluation Methodology in Carbonate Rocks During Oil and Gas Fields Prospecting
Authors K.I. Bagrintseva, A.P. Afanasenkov and D.A. AstashkinThe problem of carbonate rocks study as well as their potential evaluation seems to be the most important aim. Discovery of great and unique oil and gas deposits in carbonate rocks related to different age and origin, considerable filtration and capacitive parameters variation, uncertainty of effective thickness determination has issued the challenge of new technique elaboration for reliable estimation of reservoir types and properties. Principal distinction of methodology used in VNIGNI for carbonate core study consist in using cubic core samples (with side 5 cm) and application of capillary defectoscopy. Ratio between fractures, cavities and pores filled with luminescent liquid or only fractures presence allows to estimate pore volume in carbonate rocks: distinguish layers with mainly pore channels or complex structures (simultaneous pores, cavities and fractures available) as well as rocks with system of fractures. Nature and morphology of hollow spaces determined by luminophore is rather diverse that permits to locate reservoirs of different types in section and evaluate fractures participation in filtration and porosity
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Generalization of Core Researches Results of the Bazhenov Formation Deposits in the Central Part of Western Siberia
Authors V.D. Nemova, I.V. Panchenko, M.E. Smirnova and A.M. KirsanovThe results of many years of core researches of the Bazhenov formation in the Central part of Western Siberia are given. The amount and method of studies is shown. Examples of the detailed structure of the Bazhenov formation in different areas are given. The conclusions about the geological structure of the sediments and laterally variability of the strata are shown. The necessity of application of different algorithms for remote methods interpretation of the Bazhenov formation with different types of reservoirs are shown.
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Comparative Study of Different Oil and Gas Relative Permeability Models for Iranian Carbonates [A Statistical Approach]
Authors S.M. Alavi and A. AryanzadehLaboratory measurement of relative permeability including steady state and unsteady state methods are expensive and time consuming. Due to these shortcomings, several models for predicting and obtaining two phase relative permeabilites have been developed in literature. This study involves the comparison of different oil and gas relative permeability models with three experimental datasets from laboratory tests conducted on Iranian carbonate rocks. The comparison method includes a statistical approach for determining the best model performance applied to the model predictions. It found that Koederitz model gives closest fit to relative permeability ratio obtained from experimental data sets and it is followed by Wylie and Mohamad Ibrahim.
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Enhanced Wireline Core Size Retrieval By Casing Drilling Coring
Authors R. Ashena, G. Thonhauser, W. Vortisch, A. Roohi, C. Daws, C. Koller and M. ProhaskaAs one basic objective of coring methods applied, core size retrieved should be adequate (particularly in slim holes) so that appropriate results can be obtained from core analysis and also mechanical tests. However, conventional wireline continuous coring method is suffering from meeting this objective particularly in slim holes (particularly smaller than 5 ½-in) even by specialty drill pipes and jars with larger bores. Thus, in this paper, following attempting to remove the difficulties of grasping the wireline exploration drilling and translation possibility from mining to petroleum drilling, it is emphasized on utilization of casing drilling coring by replacing BHA and pipes with drill rods/casings as the most optimum method of coring to retrieve largest possible cores particularly in slim holes (holes sizes less than 5 ½-in) with some reasonable drilling rig modifications required for this purpose. It is recommended to utilize drill rods and specialty API drill pipes with modified gripping so that so that it is possible to switch to API drill pipes in ultra-deep intervals where drill rods depth capacity is exceeded.
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The Structure of the Abalak Formation in Detail and Patterns of Distribution of Reservoir Rocks
Authors M. Smirnova, V. Nemova and I. PanchenkoThe sweet spot for the search for oil and gas deposits in the Abalak Formation are interlayers and lenses of carbonate rocks, irregularly distributed. These rocks have fissured-cavernous type reservoirs. The paper shows that the lenslike mass are diagenetic calcareous nodules. Detailed lithological and petrographic studies of core samples revealed patterns of distribution of nodules of the section, and to identify them as belonging to the facies type deposits. The main part of the potential reservoir rocks, carbonate nodules confined to the facies F3, developed at the base of the upper part of the Abalak Formation. Facies is represented by alternating clays siliceous dark gray and clays slightly greenish-gray with plate glauconite. The rocks of this facies, in contrast to the lower, free of mica and silt (5%), irregular carbonated and bioturbated. An integrated approach to the consideration of levels spread of potential reservoir rocks can significantly refine geological models of oil fields and methods of further exploration of hydrocarbon deposits in the Abalak Formation.
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From Digital Core Samples to Thermodynamically Compatible Model of Porous Media
Authors T.S. Khachkova, V. Lisitsa, E. Lys, M. Novikov, E. Romenskiy and V. TcheverdaWe present a digital rock physics workflow to construct the thermodynamically compatible model governing seismic wave propagation in fluid filled porous media. Starting with the X-ray microtomograms the workflow includes: - image processing techniques to construct digital model of the rock sample; - hydrodinamical modelling to estimate filtration characteristics; - static mechanical loading to reconstruct the mechanical properties of the dry rock sample; - computation of the thermodynamically compatible model coefficients. Presented approach allows to proceed from the microscale (pores, grains) to mesoscale (fractures, thin layers) model accounting for the mechanical and the filtration characteristics of the rock.
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Geomechanics - a New Specialty of Seismic
By S.L. FedotovSeismic data has long been successfully used in building of reservoir models. Building of a structural framework, sequence- and seismic stratigraphy interpretation as well as reservoir properties characterization in the interwell space are common seismic "specialties". In recent years, a new direction in the use of seismic data is actively developing – that is, in geomechanical model building. Geomechanical factors play an important role at all stages of the life of a field. As a result, there is a need to assess and manage them, starting with a forecast of drilling risks and ending with a maximization of production. Geomechanical models are vital in well planning in the sense of forecasting possible drilling problems. Wellbore stability, combined with the pore pressure determines restrictions on mud weight required for secure drilling. Reliable geomechanical model is ultimately needed while planning hydraulic fracturing in order to intensify production of hydrocarbons. Exploration for hydrocarbons in complex reservoirs and difficult conditions, as well as their further development requires improved and innovative approaches. In this regard, efficient use of seismic data in building of geomechanical models is very important.
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Three Levels of Well Log Data Interpretation In Geomechanical Modelling
Authors T. Nekrasova, K. Kozlov, I. Yakovleva and Y. PavlovskiyHistorically, standard log data interpretation has been required for geological modelling, while rock physics modelling and analysis traditionally prepare the foundation for seismic inversion, since rock physics is used to determine relationship between elastic parameters and reservoir properties of porous rock types. This is different for complex unconventional reservoirs, where matrix component contributes a small part to the overall productivity. In this case geomechanical parameters become more important for further field development of complex unconventional reservoirs: initial principal stresses in the rock, brittleness, changes of rock properties after hydraulic fracturing. In this case the role of seismic inversion is lessened to the prediction of elastic parameters between wells to progress the transition to a geomechanical model, calibrated to well data. The role of interpretation of well log data is fundamental in this process and includes three stages: the first stage is petrophysical interpretation to obtain a bulk petrophysical model, then petrophysical model is built for recovery and correction of compressional and shear velocities, finally, the last stage is determining relationship between elastic and geomechanical parameters. The suggested approach allows to constantly account for changes in the formation parameters in field development process and to make adjustments to geomechanical model accordingly.
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Analysis of Methods of Multi-Stage Hydraulic Fracturing Efficiency Assessment at Horizontal Wells
Authors M.V. Okunev, A.S. Aleshkin and P.V. Molodykhmetry in an explicit form. The main idea of this paper is the development of the methodology for the assessment of well’s performance on the basis of currently existing models. The development of the methodology included several stages: the selection of an appropriate mathematical model, its further modification and adaptation in order to meet real-life challenges, as well as examination of possible fields of application. Subject area review revealed the existence of the following mathematical models, that allow to predict the performance of the considered type of wells: Hujun Li and Zhengqi Jia, Boyun Guo and Xiance Yu, Hong Yuan and Desheng Zhou. These models formed the basis of this study. As a result of performed research, complete methodology for evaluation of the productivity of horizontal wells with multistage hydraulic fracturing, on the basis of Hujun Li model, was proposed. Several possible applications of this technique were examined. Model proved its workability in a specific geological conditions, peculiar to Western Siberia.
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Precursors of Rock Bursts in Rock Massif Using Seismological Catalogue Data Dat
Authors O.A. Hachay and O.Y. KhachayA new algorithm of seismological information processing of detailed mines catalogue with use kinematic and dynamical characteristics of deformation waves, which propagate with different velocities in the rock massif, which is under heavy influence of single blasts and technological explosions. It is estimated that the waves, which propagate with the velocities from 10 to 1 m/hour are primary carrier of the energy in the massif and promote it’s releasing. Events, which occur in the massive with these waves with releasing energy less than 104 joules promote to the creep rebuilding of the massif. Events, which occur in the massive with these waves with releasing energy more, than 105 joules, can be used as rock burst precursory and it is recommend taking into account by changing of explosions in the indicated part of the massif. The whole absence of such events indicates the growing of the stress massif state in the mine as a whole. The received joined information from the seismic catalogue is very significant for forecasting of dangerous events in the rock mines.
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A New Approach for Relating Dynamic Elastic Properties and Geomechanical Parameters Based on Rock Physics Modeling
Authors M.F. Ghasemi, I.O. Bayuk and Y. AlkhimenkovGeomechanical modeling is of great importance for different tasks of prospecting geophysics. This modeling requires knowledge on geomechanical characteristics including the static moduli (Young modulus and Poisson coefficient), the uniaxial compression strength and internal friction angle. The only way to get reliable geomechanical parameters is laboratory tests providing “stress-strain” curves. However, this way is time consuming and should be performed for many representative samples of all stratigraphic units penetrated by a well. Many empirical relations exist that allow one to relate the dynamic moduli provided by logging with the geomechanical parameters. However these relations work only locally. In this work we propose an approach based on classification of rocks with respect to their macrostructure controlling the both dynamic moduli and geomechanical characteristics. The microstructure is described by the rock’s model parameters inverted from the experimental data with the help of the Rock Physics modeling. This makes it possible to group different rocks into classes with respect to the model parameters. As a result this allows one to find relations between the dynamic elastic parameters measured in field and geomechanical and other physical parameters (not measured) for different rock groups via the rock microstructure parameters specific of each rock group.
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Stability Modeling of a Production Well in Haft Kel Oilfield Using FLAC2D
By A. BarjastehAccess to oil and gas reservoirs is confront with many problems in different parts of the exploration, drilling, exploitation and processing. Hence, stability of wells are particularly important. In order to understand and predict the causes of wellbore instability problems, making geomechanical model is necessary. In this paper, based on the data of one of the wells in Haft Kel oilfield of Iran, a geomechanical model is established regarding Mohr-Coulomb and Mogi-Coulomb criteria to define appropriate drilling mud window. Then, using the software FLAC2D, a model is constructed at four depths and stability analysis is performed. The analysis shows that the direction of maximum horizontal stress is NE-SW. The major shear fractures are SWBO and tensile fractures are TCYL. Accordingly, the minimum and maximum values of the simulated stresses are 30 and 110 MPa, respectively. The magnitude of maximum and minimum horizontal displacements along X and Y coordinates are 3×10-4 and 7.5×10-5 m, respectively. Finally, the safe and stable mud window for different drilling depths is between 17.5 and 27.92 MPa for Mohr-Coulomb criterion and between 13.01 and 27.92 MPa for Mogi-Coulomb criterion, respectively.
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Isolation of Prospective Oil and Gas Objects in the Visean-Lower Permian Complex of Timan-Pechora Province
By T.N. KrykovaFor replacement of hydrocarbon reserves one of the most effective areas of geological exploration is the identification and involvement in the development of perspective unvalued objects within the local objects where already carried out a deep drilling in different years. Analysis and integrated processing of GIS and drilling in biogenic-carbonate of Upper-Visean-Lower-Permian complex of Timan-Pechora province are revealed the promising objects in the sediments of the Serpukhov tiers of Lower carbon and of Asselian-Sakmarian stage of Lower-Permian
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Geology and Petroleum Potential of the Pre-Jurassic and Lower Jurassic Deposits of the Southern Part of the Kara Sea
Authors L.A. Zadoenko and E. FirstaevaOn the basis of the dynamic characteristics of the wave field, the analysis of time thickness and structural factors highlighted promising gas-saturated clastic sediments of the objects in the Lower Jurassic and Upper Triassic. These objects, given their relatively small depth and closeness to the land, are the prime targets of drilling to detect gas deposits on the shelf of the Kara Sea.
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Petroleum Potential of the Pre-Jurassic Deposits in the North of the Western Siberia
More LessConformability forecasts of industrial accumulations of hydrocarbons in the deep levels low, so there is a need for a comprehensive study of the geological structure of the study area and identify the geological parameters, allowing industrial zones to justify the importance of oil and gas facilities. As a result of a comprehensive analysis of geological data of deep drilling and seismic survey north of Western Siberia in the Paleozoic-Triassic oil and gas complex built schematic map of the areas the depth of the roof pre-Jurassic deposits, the main parameters of productivity of industrial zones. Based on the conducted research marked the expected direction of industrial zones of oil and gas potential within the western and southern parts aria of the Nadym-Pur on structures with a high tectonic activity.
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The Use of Simulators for Designing and Interpretation of Well Thermal Survey
Authors A. Ramazanov, R. Valiullin, R. Sharafutdinov, T. Khabirov, A. Sadretdinov, M. Zakirov and D. IslamovThermometry is one of the most informative production logging method. It is used for well and reservoir survey at all stages of well life: drilling, completion and production. The worldwide scope of temperature surveys is very large. However, despite many attempts of quantitative interpretation technique developing, the interpretation of temperature measurements remains mostly on qualitative level. In recent years, due to the ability of temperature logging by distributed sensors and to the appearance of complex numerical simulators of temperature processes in the well-formation system, the interest in the quantitative interpretation is increasing. Particular interest is obtaining individual rates and hydrodynamic parameters in multilayer system by interpretation of temperature and pressure transients. Methods for determination of reservoir parameters and mathematical models of thermo-hydrodynamic processes in the well-reservoir system are described in a number of the papers of groups at Stanford University, Texas A&M University, Bashkir State University in cooperation with the Moscow Research Center of Schlumberger and company TGT. The paper considers mathematical models of thermo- hydrodynamic processes in the well, reservoir and surrounding rocks as well as examples of temperature simulator using for survey designing for different well types and for interpretation of field data.
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Joint 2D Inversion of Induction and Galvanic Borehole Sounding Data When Logging Hydrocarbon Reservoirs
Authors I.V. Mikhaylov, V.N. Glinskikh, M.N. Nikitenko and I.V. SurodinaThis paper concentrates on improving the reliability of hydrocarbon saturation estimation while investigating oil and gas reservoirs. We base on algorithms for multidimensional numerical simulation and inversion, as well as utilize a complex of induction and galvanic borehole sounding signals. We have developed software for joint numerical inversion of induction and galvanic log data within a consistent axially symmetric earth model. There is no need in depth matching since all the logs are recorded during one round-trip operation. We have reconstructed the spatial resistivity distribution around the borehole, taking into account enclosing rocks and thin impermeable carbonate and clay interlayers. Due to applying the joint inversion, one significantly reduces the zone of ambiguity in the inverse geophysical problem.
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Adaptation of Petrophysical Basis for Seismic Geological Modeling on the Example of the Tyumen Formation Sediments
Authors Y.A. Kalacheva and E.A. CherepanovIn connection with the high degree of hydrocarbon’s decrease from the largest and most productive oilfields, the main reserve of oil stocks became resources associated with inhomogeneous and low-permeable collectors. The fact mentioned above leads to the necessity of a detailed geological and geophysical study of oil and gas reservoirs, constructing the appropriate models. The developed technique of interpreting the log data based on point-wise evaluation of parameters, allowed to establish the petrophysical characteristics of thin collectors, the most important for sediments with a high degree inhomogeneity
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Some Petrophysical Aspects of the Interpretation of Volcanic Rocks and their Weathering Crusts
By B.N. EnikeevBased on of generalization of petrophysical publications and processing of empirical data offered statistical relations for the volcanic rocks and their weathering crusts. Algorithms of practical use of the received results are offered.
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Sparsity Promoting Least Squares Migration for Laterally Inhomogeneous Media
Authors A. Siahkoohi and A. GholamiThe aim of this correspondence is to introduce a sparsity promoting least squares migration method using a generalized F-K migration operator that can compensate for lateral velocity change. In addition with help of sparse regularization the method finds a non-smooth model that has a higher resolution compared to a typical least squares migration algorithm and reduces the artifacts. The efficiency of the method is tested on synthetic seismic data.
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Decision Makng Based on Digital Oil Field Concept
Authors K.N. Milovidov and A.G. GululyanDigital oil field (DOFF) led us to a significant increase in exploration, development and exploitation efficiency. The benefits of using DOFF can be represented as three kinds of effects: Productivity, Performance and Profitability. Long life of oil and gas projects allows management to manage the creation of shareholder value, using a multi-step process diagram. We consider three stages in the life cycle of the field where seismic 4D can bring added value. There are presented characteristics of the potential effects and economic benefits from 4D seismic survey at every stage.
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An Approach to Control Oil Field Development System for Heterogeneous Reservoir with Complex Structure
More LessThis paper describes the developed software module for the evaluation of forward watercut growth that can automatically carry out an individual estimation of the development for each element of the waterflooding system. This tool is useful for diagnosis and forecast of forward watercut growth of production wells for fields developed with a waterflooding system. A method of diagnosing zones with probable forward watercut growth can detect critical deviation, make quick changes to the system of waterflooding system and to avoid oil production loss.
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Presence of Oil-Degrading and H2S-Producing Microorganisms in a Brownfield Hypersaline Sandstone Oil Reservoir
Authors U. Sognstrup Thomsen, T. Lundgaard and S. HatscherMicroorganisms living in the harsh environment present in oil field reservoirs are known to cause souring, plugging, and corrosion. A field survey was therefore conducted in an oil field located in Northern Germany that is producing out of the Valanginian sandstone of the Lower Cretaceous. The production started more than 50 years ago and there are still over 80 water injection and production wells active. The reservoir is located at a depth of 3600 to 4500 ft. Microbiological diversity was high in fresh core samples with 21 genus identified. Sulfate-reducing prokaryotes were dominating the microbial population and included species of Desulfosalsimonas propionicica, Desulfoto¬maculum geothermicum, Desulfonatronovibrio magnus, and Archaeoglobus fulgidus. Other species found were oil-degrading species of Orenia sp., Gracibacillus sp., Paraliobacillus quinghaiensis, Halanaerobium alcaliphilum, and methane-producing Methanoculleus sp. and Methanolinea tarda. Yet, microbial numbers were not exceeding 10^4 cells/g in the fresh cores and were not detectable in the fluids at the wellhead. Salt contents, reservoir temperature, and available nutrients did not facilitate growth and detrimental effects of the production facilities were not significant. Molecular microbiological methods provided valuable data for assessment of souring, microbiological influenced corrosion, oil degradation and subsurface monitoring can be correlated to the reservoir conditions.
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Considerations of Cementing Directional Wells in High-Pressure, High-Temperature Conditions
Authors S.S. Tabatabaee Moradi and N.I. NikolaevThe high-pressure, high-temperature cement systems usually contain high concentration of solid materials to adjust their properties and meet the essential requirements of these conditions. However the presence of these solid materials limit their application for construction of directional wells, as the speed of solid material precipitation will increase by increasing the inclination angle. In this work using experimental methods the stability of specially developed cement systems have been investigated. New additives have been applied to get stable cements. Also to ensure that the problem of sedimentation instability will not occur, the filtration test has been carried out at elevated temperatures and pressures. The developed system shows high degree of sedimentation stability.
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Cold" Technologies for Enhanced Oil Recovery from High-Viscosity Oil Pools in Carbonate Reservoirs
Authors L.K. Altunina, V.A. Kuvshinov and I.V. KuvshinovTo enhance oil recovery and intensify the development of heavy and high-viscosity oil pools with low reservoir temperature without steam stimulation we have proposed "cold" physicochemical technologies using sols and oil-displacing systems with controlled viscosity and alkalinity having low freezing points (minus 20 ÷ minus 60 оС). Presented are the results of pilot tests of the EOR technologies carried out in 2014 on the test plots of the Permian-Carboniferous deposit in Usinsk oil field developed by a natural mode. There has been an increase in oil production rate and stimulation of the development. The EOR technologies demonstrated high efficiency and have been recommended for commercial application. Commercial use of the new EOR technologies will enable to prolong the profitable exploitation of the oil fields being at a later stage of their development and to involve in the development deposits with difficult-to-recover reserves, including heavy and high-viscosity oil pools and oil fields located in the Arctic region.
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Fluid Flow Prediction under the Influence of Interwell Connectivity in the Well Development System
Authors M. Bolshakov, A.A. Pustovskikh, T.A. Deyeva and M. NaugolnovIn this paper interwell connectivity has been studied. Literature review of existing methods was made which is divided into three groups:Statistically-Based Methods, Material (fluid) Propagation-Based Methods and Potential (pressure) Change Propagation-Based Method. First and second groups have disadvantages. The last group considers changes of well conditions and fluid flow through porous media. In this work Capacitance method has been chosen for research. This method based on material balance and uses weight coefficients lambdas for estimation of wells influence. In the next step synthetic model was created for examining of CM. CM gave good results, flow rates which were calculated by using analytical method (CM) shows matching with flow rate in model. Further new synthetic model was created with six producers and one injector well. Also synthetic model was created which has three injectors and thirteen producer wells. This model simulates seven-spot pattern production system. Finally Capacitance method has been adjusted on real data of oil Field Ω. In this case CM gives not enough satisfying results forfield data liquid rate. In conclusion, recommendations for simplicity of calculation by CM were given. FieldΩ is assumed like one injector and one producer wells. In this case satisfying results for production rates and cumulative production were obtained.
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Probabilistic Velocity Model as a Tool for Structural Uncertainty Analysis
Authors A.A. Bogatyrev, D.S. Kutcheryavenko and А.А. GlebovReservoir characterization process is a complex data integration exercise. There is no any data type which can provide enough field information on its own. Therefore it must be a multidisciplinary approach which should allow to any data type brought into the modeling process to be geologically reasonable. Effective integration requires estimates of the uncertainties of each data type in order to make created model to be effective in reduction of exploration and development risks. We propose to use probabilistic approach for velocity model construction. We present the methodological aspects of building a probabilistic velocity model. The prerequisites for the application of the probabilistic approach are: a necessity for a statistical analysis of velocity heterogeneities, estimation of structural constructions accuracy within the chosen technique of construction, necessity for uncertainty analysis and framework formation for field full-scale probabilistic model, assessment of the impact of structural uncertainty on field exploration and development. The advantages of this method in our opinion are: possibilities of taking into account statistical information, deterministic and a priori data, as well as the fact that the method of structural accuracy estimation is an integrated part of the modeling process.
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The Relative Permeability Regions Assignment on the Basis of Pore Network Models Parameters Distributions
By P.V. MarkovOne of the most important parameters for a reservoir model is relative permeability. But despite the relative permeability importance it is very hard to find a case where we have enough experimental data for a reservoir model. This problem demands a solution if reliable forecasts of oil and gas production values using reservoir models are desired. It can be solved by joint using of all available experimental data such as core, well log interpretation and other data. This report is intended to present an approach for relative permeability regions assignments on the basis of pore network models parameters and their correlations with well log interpretation data. The approach allows to calculate relative permeability using a powerful and flexible instrument such as pore network modelling with many factors taken into account. Correlations with well log interpretation data give an opportunity to set more justified spatial distributions for different types of relative permeability curves in a reservoir model.
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Optimization Workflow for Modelling of Two Phase Thermal Multicomponent Filtration
Authors L.A. Khakimova, A.V. Myasnikov, Y.S. Melnikova and A.M. ZhabkinaWe present in this paper newly developed optimization workflow for modelling of two phase thermal multicomponent filtration. By making use approximation of phase equilibrium at the preprocessing stage, we can then construct numerical solution depending which is the faster the lower is desired accuracy. Another key parameter for the workflow is a number of splits of both temperature and pressure ranges where we perform approximation of phase equilibrium. Besides, we implemented a two-parametric family of TVD MUSCL scheme in our research code which also makes it possible to attain desired accuracy at of order 10 times less number of grid points than if conventional first order approximation scheme is used. All that make it possible to run a huge number of experiments to determine the influence of non-stationary borehole pressure regimes on gas condensate wells performance.
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The Value of Geological Knowledge to Build Realistic Representations of the Reservoir and Manage Uncertainties
Authors A. Zhivodkov, E. Bileva, G. Samotorova, S. Mutaev and E. ShkunovNowadays some static models still consider only two types of rocks, reservoir and non-reservoir, populated in the 3D grid with statistical or geostatistical methods lacking solid geological ground. These models are easy and fast to build, but do not correspond to a realistic representation of the reservoir heterogeneities that will impact the fluid flow simulation. In addition, managing uncertainties is almost impossible for these models since, for example, each cell may mix different petrophysical populations or reservoir cells may belong to different types of sedimentary bodies with very different extensions. Geological knowledge, and specially sedimentary understanding, is essential to identify the main reservoir heterogeneities (from an integrated interpretation of cores, logs and seismic data) and define some rules to extrapolate them in 3D in order to achieve a realistic reservoir geometry, internal architecture and 3D distribution of petrophysical properties. The example of one field demonstrates below, that the integration of additional sedimentological knowledge into static reservoir models is key to realistically control the petrophysical properties’ population in 3D, and finally helps to manage the uncertainties of the field
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Integrating Outcrop and Subsurface Data for 3D Modeling of Outcrop Analogs: a Triassic Example
Authors L.M. Yeste, N. McDougall, S. Henares and C. ViserasWe present the 3D modeling of a Triassic sandstone geobody interpreted as a single-story meandering river channel and its genetically related deposits. On outcrop the sub-environments of main channel, point bar, scroll bar, chute channel and flood plain have been recognized. There have been conducted four boreholes with core recovery and obtaining well logging records of Natural and Spectral Gamma Ray as well as Acoustic and Optical Televiewers. The integration of all of outcrop and subsurface data has allowed us to develop robust 3D static models. The modeling strategy shows that the deterministic models quite accurately reproduce the heterogeneity in the distribution to lithofacies observed in outcrop. However, the models obtained by stochastic methods are not as accurate to reproduce facies heterogeneity but adequately simulate the petrophysical heterogeneities of porosity and permeability.
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Integrated Geological and reservoir study of the Ri and Hamra Quartzite reservoirs of Hassi Guettar field - Oued Mya Basin
Authors N. Maache, D. Boufedda and S. ZemitiThe HGA field is located in the SW edge of the super-giant Hassi Messaoud oil field. The producing reservoirs are Cambrian Ri-Ra and Hamra Quartzite reservoirs. A geological, reservoir characterization and rock-typing study was carried out for a robust static model construction required for a simulation model in order to implement a strategy for enhanced oil recovery (EOR). Detailed reservoir zonation using high resolution sequence stratigraphy integrating the cores and logs data and applied to the 34 wells allow the subdivision of Cambrian to 09 and HQ to 06 high resolution sequences. The Ri-Ra and HQ reservoirs comprises a distinctive suite of facies representing a range of depositional environments from alluvial fluvial channels sediments to coastal plain crossed by fluvial-tidal channels. The reservoir quality is mainly controlled by depositional and diagenetic processes. Rock-typing workflow in Techlog was ues in conjunction with SCAL data and observed dynamic performance to determine a representative distribution of reservoir properties. A 3D geological model was constructed in Petrel with the main reservoir properties distributed . The reservoir properties distributed (Porosity, permeability, Sw).This model served for the volumetrics estimates and uspscaled for dynamic model simulation for the history matching and the re-development plan to achieve higher recovery.
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Combination Drive Mechanism Simulation During Production in Carbonate Oil Reservoirs
Authors A. Khormali, D.G. Petrakov and H. JafarpourThe drive mechanism of a reservoir influences on many of the indicators of oil field, including gas factor and reservoir pressure. Ultimate recovery factor and efficiency of operation of the oil field depend on the proper consideration of the reservoir drive mechanism. In this work, a combination drive system with depletion, gas cap and water drives is considered for a carbonate reservoir. Production characteristics of the reservoir are simulated by making a new model for 30 years. Simulation results show that after long time gas production rate approximates to the same value for all drives. The recovery factor for the combination, depletion and gas cap drives goes to the same value at the end of reservoir production and this value is less than the recovery factor value in the case of water drive mechanism. The oil production rate for the gas cap, depletion and combination drives goes to very small value; in water drive case, the final value of production rate is considerably high. The growth of total produced oil in water drive is a straight line, but in gas cap and combination drives, the total production deviates from the straight line after the first half of the production.
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The Use of Hydraulic Flow Units and Neural Networks to Improve Rock Types Estimation and Reservoir Models: A Case Study
Authors Ana de Sousa, P. Bizarro and M.T. RibeiroOne of the largest challenges in reservoir modelling is to obtain representative Reservoir Rock Types for permeability and saturation modelling. The present case study provides an example from a complex siliciclastic reservoir, where an integrated Fishbone workflow was applied. Rock typing concepts can be used to establish the relationship between petrophysical data from standard well logs and core data, through the utilization of Hydraulic Flow Units and Neural Networks. Flow Zone Indicator, Rock Quality Index and Hydraulic Flow Units were calculated using mathematical equations through a dedicated software. The application of Principal Components Analysis allowed the identification of the logs to be used in Neural Networks, thus enabling the propagation of the cored-based reservoir properties into the non-cored wells. Finally, a set of logs consisting of porosity, permeability and reservoir rock types were used in the reservoir modelling.
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Sergey Vasilyevich Goldin: Tyumen period of scientific work
More LessOn January 26, 2016 is the 80th anniversary of birth of Sergey Vasilyevich Goldin - the famous teacher, outstanding scientist, and personality. He was very talented man. In addition to science Sergey Vasilyevich was keen on classical music, played the mandolin, composed poetry, painted pictures, and went in for sports. I adore him for intelligence, but first of all he is the Teacher for me.
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Reflection FWI in MBTT Formulation: Macro Velocity Reconstruction
Authors V. Tcheverda, K. Gadylshin, G. Chavent, C. Shin and J. ShinUnfortunately we have to admit that after decades of development there are still no reliable techniques of full waveform inversion which guarantee reliable reconstruction of both macrovelocity model and reflectors reconstruction for reasonable acquisitions and frequency ranges. As reasonable we mean realistic offsets (about one-two depths of target objects) and temporal frequency above 5 – 7 Hz. The paper is devoted to the so-called Migration Based Travel Times (MBTT) formulation of the data misfit functional. This approach relies on the decomposition of a velocity model onto two subspaces – smooth propagator and rough depth reflectors. On this base the modified data misfit functional is introduced and compared with standard least squares formulation. Numerical Singular Value Decomposition proves that these two formulations produce functionals which have almost orthogonal stable subspaces. As is well known the classical formulation leads to stable subspaces mainly made of fast oscillating functions (reflectors). At the same time we prove that MBTT modification ensures appearance of the propagator in these stable subspaces. Numerical experiments prove the feasibility of full inversion for reflected waves in this modified reformulation for the well known Gullfaks velocity model.
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Full waveform inversion for elastic medium using quantitative Lipschitz stability estimates
Authors H. Barucq, H. Calandra, M.V. De Hoop, F. Faucher and J. ShiWe study the seismic inverse problem for elastic isotropic medium associated with the time-harmonic wave equation, in particular the recovery of the Lamé parameters. We employ full waveform inversion (FWI) where the multi parameters reconstruction is based on iterative minimization techniques. This inverse problem shows a Lipschitz stability where the stability constant is related to the (conditional) lower bound of the Frchet derivative, when assuming a piecewise constant representation of the parameters. We successively estimate the stability constant for different model partition to control the convergence of our scheme. Hence we define a multi-level (multi-scale, multi-frequency) algorithm where the natural progression of frequency is paired with the model partition. We implement our new scheme and present numerical experiments for elastic parameters reconstruction assuming no-prior information in the initial models.
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Multiscale Medium Approximation: Application to Geophysical Benchmarks
Authors H. Barucq, H. Calandra, T. Chaumont-Frelet and C. GoutHigh order finite element methods are very efficient to approximate the solution of wave propagation problems in the high frequency regime when the propagation medium is homogeneous. Unfortunately, theses methods fail to handle small-scale heterogeneities if the mesh is not properly constrained. In geophysical applications, constraining the mesh to the size of small-scale heterogeneities might be unaffordable so that high order finite element methods can not be applied directly. We propose to overcome this limitation by considering a multiscale strategy, which makes it possible to take into account small-scale heterogeneities on coarse meshes. Our multiscale procedure is equivalent to a quadrature-like formula. It thus corresponds to a pre-processing step in the computations which can be easily parallelized. Hence, the overhead of our multiscale technique is negligible. We validate the accuracy and the efficiency of our methodology on 2D and 3D geophysical benchmarks.
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The Combining of Theoretical Solutions with Real Seismic Observations
More LessThe questions of combining the solutions of the inverse dynamic problems for thin-layer elastic models in spectral domain are considered. The problem of combining is analyzed from two points of view: (1) the transformation of the observed data with the aim of increasing their compliance to model assumptions and (2) the influence of characteristic properties of real data at the theoretical solution. As a result of the conducted research was able to provide the best combination of theoretical solution and two-dimensional spectra calculated from observed seismograms. The proposed approach creates conditions for more active practical application of modern theoretical methods of solution of direct problems and extends the possibility of solving inverse problems using real multi-component observations.
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Seismic Inversion: What it is, and What it is Not
Authors E. Landa, S. Treitel and V.A. TcheverdaSeismic inversion is an ill-posed problem. All currently used inversion algorithms are at best approximations. As a result, we face the problem that many models of the subsurface give raise to synthetic data, all of which fit the data within a given measure of error. It is the job of the experienced seismic interpreter to choose among this set of well-fitting models those that are geologically most plausible, given the interpreter’s experience and prior geological knowledge of the area being explored.
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High Resolution Diffraction Imaging of Small Scale Fractures in Shale and Carbonate Reservoirs
Authors A.M. Popovici, T.J. Moser, I. Sturzu and C. TsingasCurrent research in the field of seismic depth imaging has identified a new approach to image with superresolution fractured zones, fault edges, small scale faults, pinch-outs, reef edges, channel edges, salt flanks, reflector unconformities, near surface scattering objects and in general any small scattering objects, by using Diffraction Imaging as a complement to the structural images produced by reflection imaging. Diffraction Imaging is the imaging of discontinuities in the earth. Diffractions are the seismic response of small elements (or diffractors) in the subsurface of the earth, such as small scale faults, fractures, near surface scattering objects and in general all objects which are small compared to the wavelength of seismic waves. We show results in different areas of the world, in fractured carbonate and unconventional shale reservoirs. Using Diffraction Imaging to identify areas with increased natural fracture density, which correlate with increased production, the reservoir engineers can design an optimal well placement program that targets the sweet spots and minimizes the total number of wells used for a prospective area.
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The Study of Anisotropy in Orientation of Fractures by Azimuth Distribution of Seismic Scattering Energy
The paper presents an approach to reconstruct dominant fracture orientation of the reservoir via azimuth variability of surface scattering seismic energy. The approach is validated for both synthetic and real field data. The approach can be applied for to optimize location of horizontal wells in order to ensure crossing the greatest number of fluid saturated fractures and, hence, maximize the influx.
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Modeling of Crustal Structure in Siberia and the Far East According to the Wide-Angle Seismic and Gravity Along the 3-DV
Authors V.D. Suvorov, E.A. Melnik, E.V. Pavlov and A.S. Salnikovt of the Siberian platform) and the Verkhoyansk-Kolyma fold area have been carried out seismic observations to study the deep structure and its relation to mineral specialization of major geological provinces. The modeling results of the crust according to the waves in the first and second arrivals from the observations in offsets up to 40 km (refraction data) and deep seismic soundings up to 300-400 km are considered. The forward ray tracing method was used to model the spatial distribution of velocity irregularities. The correlation between the seismic inhomogeneity’s in the upper crust and tectonic units according to geological mapping (website vcegei.ru/pub_ggk1000/Verhoyano-Kolymskaya/p-56.php) is found. However, geological structures, extended to a depth of 6-8 km are different from the seismic features. Correlation between gravity Bouguer anomalies and velocity structure of the crust and upper mantle is considered. A number of regional velocity features identified in the crust, the geodynamic nature of which and their influence on the formation of surface geological structures remain unclear.
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Absorbing Boundary Conditions for 3D Elastic TTI Modeling, Application to Time-Based and Time-Harmonic Simulations
Authors L. Boillot, H. Barucq, J. Diaz and H. CalandraWe propose to tackle the critical issue of designing boundary conditions for TTI elastic wave equations by formulating a stable low-order Absorbing Boundary Condition (ABC). The construction principle is based on ellipticity which simplifies the slowness surfaces into ellipsoids of revolution. Then, a change of variables is used to deduce the TTI ABC from the isotropic one. Moreover, we derived a source formula which generates P-waves only on an elliptic TTI medium. Numerical experiments are performed to illustrate the performance of the ABC in both time-based and time-harmonic 3D cases and to show the long time stability of the condition.
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Solving Helmholtz Equation by Means of Domain Decomposition Using Discontinuous Galerkin and Pseudospectral Methods
Authors K.V. Voronin, V.V. Lisitsa, D. Neklyudov, G.V. Reshetova, C. Shin and J. ShinIn this work we introduce and study numerically a new method for solving two-dimensional Helmholtz equation in complex media with high-contrast velocity variations. The proposed method is based on coupling the IPDG method for solving the problem in the surface neighbourhood with fast pseudospectral method applied in the lower part of the domain. The coupling is implemented using overlapping domain decomposition with Robin transmission conditions. Results of numerical experiments with both analytical solutions and point-like sources are presented for Gullfaks benchmark.
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Petrophysical Interpretation of Seismic and Gravity Data (the Example of the Muya Depression)
Authors E.A. Melnik, V.D. Suvorov and Z.R. MishenkinaPresents the results of studying the nature of P- and S-wave velocity and density anomalies in the upper part of the Earth’s crust in reliance on variation in the parameter of petrophysical heterogeneity in the Muya Depression of the Baikal Rift Zone. The use of the complex parameter of petrophysical heterogeneity indicates the possibility to separate the effects of influence on seismic velocity and density. These effects are related to both fracturing, which decreases under pressure, and material composition change. In the Muya Depression, at depths down to 8 km, one may distinguish distinct, partially discontinuous petrophysical anomalies, penetrating up to 10-25 km in the form of three narrow sloping areas. The obtained data imply the possibility of depth mapping of faulted zones represented by material heterogeneities. It is of concern when detaching structures in the Earth’s crust, which control distribution of mineral deposits.
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Analisys of Linear Variation of HTI Axes from VSP Data: a Model Study
Authors S.B. Gorshkalev, W.V. Karsten, I.A. Karpov and D.M. VishnevskiyA 3D horizontal layered model with two HTI layers with linear variation of symmetry axes direction is used for finite difference VSP data modeling. The model data is used to test the ability of polarization analysis methods to determine the symmetry axes orientation near the borehole and its variations. Both pseudo-rotation and cross-correlation techniques produced the results with accuracy of few degrees.
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Polarization Analysis of Refected ps-Waves in an HTI Medium with Varying Axes Direction
Authors E.V. Afonina, S.B. Gorshkalev, W.V. Karsten and D.M. VishnevskiyThis article presents the results of processing of synthetic 3D-3C data acquired in a model comprising inhomogeneous azimuthally anisotropic layers. Anisotropy parameters of the upper layer were determined using the pseudo-rotation method. This allows removing PS-wave birefringence in the upper anisotropic layer for investigation of the anisotropy in the lower layer.
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Features of Thermohydrodynamic Studies of Directional Wells with Multiphase Flow
Authors R.F. Sharafutdinov, R.A. Valiullin, A.S. Ramazanov, T.R. Khabirov and I.V. KanaphinResearch methods and data interpretation previous studies based mainly on views in single-phase flows of oil, water or gas. In most cases, under real conditions observed multiphase flow in reservoirs and wells. Temperature field formation in this case due to the manifestation of the Joule - Thomson adiabatic effects and the warmth of the gassing of the liquid. The patterns of change in temperature anomalies is based informativeness thermal method of research of wells and layers. The paper discusses the characteristics of thermohydrodynamic fields in vertical well-layer when moving multiphase flow. Examples of numerical calculations and borehole studies. Non-isothermal multiphase flow in the wellbore of horizontal wells is observed with the joint input of several phases from the formation, the release of dissolved gas, in flooding an oil-bearing formation. For the correct assessment of the current state of production the field needs to know quantitatively the phase composition and the flow profile. The paper presents features of the calculation of the phase costs in deviated and horizontal wells, based on mechanistic modeling and experimental data obtained in the hydrodynamic stand. The paper presents the results of field studies in boreholes drilled in various geologic conditions of oil fields of Russia
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Fourier Spectrums Clustering for Automated Facies Recognition of Field Y
Authors D.I. Tengelidi, V.S. Rukavishnikov, M.Y. Mityaev and O.M. FuksFacies determination is a key parameter for proper modelling of reservoir behaviour. The subject of current research is optimization of interpretation process and decreasing the subjectivity in facies determination through the automated process of facies recognition based on Fourier spectrums clustering of SP logs. Spectral method is based on decomposition of SP curves into Fourier series consisted of basis of periodic functions orthogonal on the interval. Main attributes for clustering are Fourier coefficients, energy, homogeneity degree and slope of spectral density. EM algorithm is applied for clustering including opportunity to estimate the probability of facies recognition. Advantages of method are combination of parameters, which responsible for curve shape as a combination of different scale heterogeneities correlatable in the interwell space. Also the results of clustering allows considering descriptive geology in the mathematical sense, which reduce the interpreter bias and make it possible to correlate the facies of different reservoirs with the same attributes. The automated facies recognition is applied in the Field Y which is situated in Western Siberia, accounts 1774 wells with SP log distributed in the 268 km2 area. Methodology proved itself as a reliable tool for facies recognition with probability of 84% for known facies of reservoir bs11c
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Importance of Blocking in Petrophysical Interpretation
More LessProper determination of bed boundaries in layered reservoirs is vital for accurate petrophysical interpretation of conventional logs. In the wellbore, logs continuously measure physical properties of reservoir while the properties change stepwise. This continuous representation of logs may lead to ignorance of some high potential reservoir zones. The main reasons for continuous nature of logs in laminated reservoirs are the influence of shoulder beds on the reading of logging tools and low vertical resolution of these devices. In this paper we optimized a Laplacian filter to detect bed boundaries in conventional well logs. These blocking-based boundaries are validated with FMI derived bed boundaries. Then the calculated petrophysical properties including porosity and volume of minerals and fluids are distributed into the detected beds. Comparison of petrophysical interpretation of logs based on blocking and FMI derived bedding showed that the petrophysical properties realistically distributed into beds in layered reservoirs with the blocking technique. The results also showed that blocking reduces the uncertainties, because it realistically distribute the petrophysical properties inside real geological beds and alter the noises.
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Special Features of Studying Artinskian Siliceous-Carbonate Rocks from Core and Well Log Data
Authors D.V. Klyazhnikov and M.D. FedorovaThe identification of stratigraphic interfaces from well logs can be accomplished using a combination of Discrete Wavelet Transform and Fourier Transform. This study illustrates how gamma ray logs and density logs can be used for the same. The study highlights the success of this method and how it is very convenient to use and how well it scores over conventional techniques. The study also highlights a methodology for identification of lithofacies from well log data without the usage of any core information. This is accomplished by using a combination of Discrete Wavelet Transform and Continuous Wavelet Transform . The methodology is able to throw light on the energy of the depositional environment and distinguishes sediments from low and high energy depositional systems. The methodology is able to identify lithofacies and distinguish between shale and claystone from density and gamma ray logs.
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Mineral Composition and Secondary Porosity Evaluation from Well Logs in Fractured and Vuggy Carbonate Reservoirs of the Timano-Pechora Province
Authors P.S. Kulyapin, T.F. Sokolova and Y.S. SinyakinaOur research is about solving a challenging case of carbonate formation evaluation complicated by secondary porosity and consisted of many minerals with use of modern well logs. We considered and proposed techniques, helped us to identify zones with fractures and vugs, quantify parameters of secondary porosity, and take into account the influence of secondary porosity on well logs when performing well-data analysis. Deterministic and statistical (inversion) approaches have been applied to solve the task of evaluating multi-mineral composition and total porosity, QC procedures have been developed. A new model for well-data interpretation, considering more details of rock composition and structure, provided better understanding of geological peculiarities and reduced uncertainties in subsequent oil and gas exploration
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Well Log Based Assessment of Oil and Gas Bearing Deposits of the Khadum Suite in the Ciscaucasia Region
Authors A.A. Galperina, V.N. Chernoglazov and A.V. GorodnovThe Oligocene source rocks of East Ciscaucasia are represented by argillite-like clays with inclusions of siliceous and carbonate materials. They are often referred to as the “Khadum Suite” or “Khadumity” in the specialized literature (similarly with “Bazhenite” in Western Siberia and “Domanikiti” in the Cis-Ural region). Studies of the Khadum Suite launched in the late 1970s have not produced a fully developed technique for the reservoir properties estimation on the basis of well log data as well as a final version of petrophysical model yet. In this paper we discuss the ways to evaluate anomalous pore pressure, organic matter content, and construction of volume petrophysical models of the Oligocene source rocks using limited sets of old well logs from 1950s.
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Stratigraphic Interfaces and Lithofacies Recognition of Well logs: A Fourier and Wavelet Based Approach
More LessThe experience of studying Artinskian sediments in a number of oil and gas fields in the Timan-Pechora Province showed that the solution of the problem of reservoir delineation, petrophysical properties evaluation and saturation character determination is an extremely difficult task. Building petrophysical models of reservoirs presents some difficulties due to low porosity and permeability of the rock matrix, multi-component composition and significant lithophysical heterogeneity of the rocks. Using a standard set of laboratory core analysis and well logs does not allow to reliably determine the mineralogical composition and total porosity of the rocks studied, which ultimately leads to an incorrect evaluation of secondary porosity and, as a consequence, types of reservoir rocks. Identification of permeable intervals in the Artinskian section without the use of modern set of well logs is almost impossible.
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Dual Laterolog to Array Laterolog - A New Method Based on Digital Focusing Coefficient
Authors J.S. Gao, J.M. Sun, Y.J. Jiang and L.K. CuiA new digital focusing method with different bucking coefficients is introduced, with no change in the conventional dual laterolog device, compared to the hardware focusing method. The conclusions can be achieve that using the new digital focusing method, we can get array measurement similar to the result obtained by array laterolog devices, on the other hand ,the error in hardware focusing method badly affects the measurement. This new method can be considered to be applied in the laterolog, with simple device which can save economy cost and be operated more easily.
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Aspects of the Log Data Analysis in the Thinly Laminated Terrigeneous Deposits
Authors Y.S. Sinyakina, T.F. Sokolova, D.Y. Golovanov and V.A. NikitinaProductive terrigenous deposits are essential for the development of Russia oil and gas industry. Thinly laminated sediments occupy a special place among the different types of terrigenous reservoirs. Study of thinly laminated anisotropic sections is important at the moment as this reservoir type is widespread both in Russia and abroad. Anisotropic reservoir represents as a thinly interbedded reservoir and non-reservoir layers. When investigating of this section tape there are a number of difficulties relating first of all with net pay thickness determining. Secondly, there are difficulties associated with low vertical resolution of well logging. Thus properties of this complex reservoir type complex must be evaluated using a special interpretation technique different from the technique for "traditional" terrigenous reservoirs. The report suggests various ways for parameters estimation of the thinly laminated reservoirs. The possibilities of the modern well logging tools using (such as 3D-induction tool, FMI) for the reservoir properties estimation are shown on the example of the Western Siberia thinly laminated terrigenous deposits
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Using of the Surface Conductivity Parameter П May be Useful
By B.N. EnikeevBased on generalization of petrophysical articles and co-processing of various empirical data studied the relation between formation factor and porosity and the cation exchange capacity. It has been shown essential similarity dependence of parameter surface conductivity P with cation exchange capacity for three different types of rocks.
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Using Elastic AVA Inversion for the Reservoirs Prediction in Deepwater Turbidite Series Offshore West Africa
Authors D. Miroshnichenko, I. Kerusov, E. Chaikovskaya and A. GrinevskiyReservoir prediction offshore West Africa in deepwater turbidites of Turonian age is a difficult seismic task. The deposits are represented by clayey series cut by a great number of narrow, winding amalgamated sandy and sandy-silty channels with dramatically changing properties. Attributes and AVO analysis showed low reservoir prediction accuracy. Rock physics modeling found that the density and S-wave velocity are necessary for the reservoir sandstones separation. Therefore, three-parametric simultaneous elastic AVA inversion has been performed. Only this type of inversion is able to calculate the required elastic properties. But it uses larger incidence angles and relatively more sensitive to signal-to-noise ratio. The seismic modeling showed that the signal-to-noise ratio on the recorded seismograms is sufficient for the required elastic properties calculation. Probabilistic approach based on the Bayes concept, with probability density functions (PDF) have been used for the lithology prediction. Due to geological complexity of the series structure the deterministic approach provides lower efficiency. Reservoir probability cube was obtained from the inversion results. Lithology cube was calculated using sand probability threshold P = 0.5. Results of reservoir prediction have high correlation with well data in contrast with other methods previously used in the field.
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Analysis of AVO Inversion Results and Verification of Interpreted Reservoirs with New Wells – Case Study for Yamal Area
Authors T.E. Keller, V.I. Kuznetsov, I.P. Yakovleva and K.E. FilippovaThere are many ways to QC results of seismic inversion, but the best of them, of course, is to compare predicted reservoir bodies with new wells data. Reservoir characterization was implemented using a probabilistic interpretation of the results of deterministic simultaneous AVO inversion followed by volume interpretation. Due to limitations of seismic inversion algorithm used in the thin-layered section with high acoustic contrasts it is possible to predict predict only the presence of the reservoir. The existing limitations reservoir bodies captured from inverted elastic volumes in general have an excellent agreement with the 28 new drilled wells. Comparison was done for 17 target intervals. Thus, the quality of the results of reservoir characterization proved their quality and accuracy, so that they can be used to optimize the further exploration drilling plans.
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Multi-Layered Seismic Inversion - a Universal Integration Method of Different-Scale Geological and Geophysical Studies
Authors V.I. Ryzhkov, D.A. Danko and S.V. FilimonenkoThanks to achievements in rock-physics geologists and reservoir engineers widely use results of seismic inversion. The main question for the experts applying seismic impedances is how to integrate the different scales of studies: from microsections to seismic frequencies. In this paper for development of oilfield litho-facial model we suggest to use multi-layered amplitude inversion (MLI) in which the solution is sought for the individual layers, being characterized by particular lithological and petrophysical properties. Realization of MLI is a problem of collaboration of geologists and geophysicists. Only in this case, we understand what thickness, lithology, facies and petrophysical parameters are characterized each of the layers at the output impedances volume. The presented results obtained on the basis of the algorithm of MLI developed by the authors showed increase informativeness of acoustic and elastic impedance estimates in case of high contrast medium. The resulted layered model makes it easier to litho-facial and petrophysical interpretation of the data, for example, by the using of different rock-physics models for each individual layer. The presented decision allows in future to take into account the anisotropy of the layers, and to implement layered stochastic downscaling.
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New CGG Methods for Quantitate Estimation of Seismic Anisotropy
Authors M. Romanenko and A. KharitonovThe development of a specialized WAZ-processing technology makes it possible to obtain more reliable characteristics of the studied environment and expands on the calculation and interpretation of the anisotropy parameters based on the analysis of dynamic characteristics of seismic data. The paper reviews new approaches to the calculation of the anisotropy parameters on the basis of the Fourier transforms, analyze their applicability, limitations and prospects of their usage.
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New technology of azimuthal inversion for anisotropy studies, and special features of seismic data preprocessing
Authors K.E. Filippova, I. Yakovleva and Y. PavlovskiyПравильное определение анизотропных свойств является ключевым вопросом при идентификации перспективных для разработки пластов. В докладе продемонстрирована технология азимутальной инверсии для изучения анизотропии и влияние обработки сейсмических данных на получаемые результаты.
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Using the Results of Azimuthal Inversion to Optimize the Development Plans of Low-Permeable Reservoirs
Authors I.P. Yakovleva, K.E. Filippova and Y.V. PavlovskiyThe study of seismic anisotropy and the different effects associated with it is the subject of advanced research for geophysicists engaged in unconventional and fractured reservoirs. Seismic anisotropy can be caused by various geological reasons, often the reason for this is the presence of the fracture interval or differences in the horizontal stresses in particular geological section. Indeed, in both cases, taking into account the causes of seismic anisotropy will have a significant impact on exploration drilling, field development optimization plans, etc. This paper presents the possibility of using the results of the interpretation of the azimuthal inversion to optimize development plans for low-permeability reservoirs. The elastic properties delivered by the anisotropic inversion are very useful to update the results of reservoir characterization. Predicted azimuth of maximum horizontal stress is valuable information for the planning of horizontal wells. For successful implementation of fracking in horizontal wells wellbore must have a direction perpendicular to the azimuth of maximum horizontal stress. Overall anisotropy parameters are key factors in identifying perspective areas and setting of horizontal wells
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Lateral Distribution Estimation of Geological Risks Related to Structural Uncertainty
Authors T.I. Khasanov, A.A. Kurkin, S.A. Fedorov and E.A. ZyzaIn this work a method of lateral distribution estimation of structural uncertainty is proposed, which considers factors of uncertainty related to determination errors of seismic data initial parameters. The estimation is delivered in a deterministic way during the analysis of internal convergence of seismic data. Determination errors of kinematic parameters are estimated: time and velocity. External convergence of seismic data with well data is taken into account. As the result, a map of standard deviation of structural surface is calculated which then is used to construct a probability (risk) map of a structural closure.
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Effect of processing procedures on the seismic signals form reflected from thin-layers objects
Authors V.N. Bespechniy, G.M. Mitrofanov and E.V. MosyaginAspects relating to the procedures of seismic data processing, in particular the summation, which can affect the dynamic characteristics of the target signals, reducing the quality of results in the interpretation of complex thin-layered objects, are discussed. Detailed studies on the effect of processing procedures on the interference signals form can significantly improve the quality of the used inverse algorithms. Such studies are especially important given the use of the now considerable multiplicity of observations, fundamentally aimed at improving the accuracy of subsequent solutions of interpretive tasks related to the regions of Western and Eastern Siberia. Researches were carried out in the framework of thin-layered models of target objects which are greatest interest for oil and gas exploration
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Synthetic Seismic Models Construction for Detailed Geological Outcrop Description
Authors E.V. Fedorova, N.V. Bukhanov and V.E. BaranovThe purpose of this study is to examine the seismic response of fluvial deposits by using the method of forward seismic modelling. The studied outcrop is located in Kemerovo Region, 250 km from Tomsk and is about 500 m in length and about 30 m height. The exposure deposits belong to the fluvial depositional environment and the age of sediments is Lower Cretaceous. In this work the synthetic model construction was provided with the help of simple convolution-based method. Modeling was performed in two software products Petrel and Madagascar. To construct the impedance cube, petrophysical properties were taken from the analogue field, which formed in similar depositional environment. The sensitivity analysis of detailed seismic pictures on the frequency change was carried out. Thus, 8 models were built in a frequency range of 25 to 200 Hz in steps of 25 Hz. Attribute analysis was provided to estimate the ability of Net to Gross ratio of fluvial reservoir forecasting by using seismic attributes. Furthermore, an analysis of the effect of fluid saturation on seismic image of fluvial deposits was conducted.
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Geoelectrochemical Methods: Response to Criticism and Discussion of CHIM and MDI Methods Characteristics
Authors S.G. Alekseev, N.P. Senchina and S.Y. ShatkevichThis paper is a response to the article [1], which discusses the various geophysical methods, classified to the category of "voodoo." As one of examples is used one of geoelectrochemical methods - CHIM (method of metals partial extraction), it is determined by the USGS (United States Geological Survey) as non-effective. This gave rise to classify this method as "voodoo". In operation performed by the CHIM, we can detect extraction of gold due to electric current. At one of the fields, it has been demonstrated that the gold was extracted in identical amounts in case of electric current presence and without it. According to the author [1], it is sufficient for the allegation that the methods do not work so good, as "it was stated." But essentially there were used two different methods - CHIM and MDI (diffusion extraction method). Results of this methods can be connected. Why, and what is different? - this questions are discussed in this paper. The report examines in detail features of both methods. The paper provides examples of their successful application in the search for a variety of mineral deposits. 1. VOODOO METHODS: DEALING WITH THE DARK SIDE OF GEOPHYSICS. SAGEEP proceedings, 2005, p.315-327.
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Integration of Non-Seismic Methods in Identifying Oil and Gas Deposits in Keeping with the Geo-Soliton Theory
Authors M.I. Ryskin, E.N. Volkova, V.Y. Shigaev and E.A. VlasenkoThe paper proposes a set of methods for identifying oil and gas deposits, including gravity and magnetic prospecting, geoelectrochemistry, soil gas sampling, and thermomagnetometry. Its distinctive feature is that it draws on methods that allow to obtain direct information on oil and gas reserves (in terms of their formation and fluidization). These are both geochemical methods and methods that combine indirect geophysical and geochemical indicators. This allows for a radical improvement in reliability of predicted results. All these methods detect a similar pattern of circular anomaly with a minimum in its center. A similar pattern of the distribution of anomalies makes it possible to present the results of the field phase in a single cartographic document compiled from all maps based on individual methods, after they have been pre-normalized to adjust dimensions. The paper provides specific examples of how these methods can be used.
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Geoinformation Technology for Prospecting of Groundwater for Water Supply of Oil and Gas Facilities in Eastern Siberia
Authors A.V. Parshin and L.I. AuzinaEastern Siberia is one of the prospective hydrocarbon areas. Existing and new fields need water to ensure the economic and technological needs. In the little-studied regions of Eastern Siberia locating wells based on direct hydrogeological features not bring the desired result.The aim is to improve the efficiency of geological exploration in the field of groundwater in complex geological and hydrogeological conditions of oil and gas fields in Eastern Siberia. To maximize the effectiveness of consolidating information and improving the accuracy of forecasting method applied expert estimations and modern GIS technology. The technology is based primarily on archival and remote of the data that allows forecast at the stage of design work. On the basis of the GIS project calculated qualitatively new spatial information, aquatic and morphostructural. Factor analysis allowed to identify from all of the geodata – compact set of indicators related to the abundance of water. For this set proposes scientifically based methods of indicators scaling and mapping. Given a method for the calculation and mapping the new complex index of watery, integrating individual features. Applied open GIS technology, significantly increasing the cost-effectiveness of geological exploration. The proposed approach has shown its legitimacy on some fields Chonskoy group.
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Space Thematic Spectral Anomalies And Forecast For Oil And Gas
Authors V.S. Antipov, E.A. Zhuravlev and K.A. VolinIt has been shown the basic methodical conditions of development and use of space thematic spectral anomalies of prospecting for oil and gas. The examples of the anomalies of the spectral brightness above the hydrocarbon deposits in Russia, Tunisia, Argentina, and Egypt are shown. The results of the forecast for oil and gas on the territory of these countries are also shown based on the identification of spectral anomalies.
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Low-Altitude Aeromagnetic Survey: Drones and High Frequency Magnetometers. Experiences and Perspectives
Authors M.I. Epov, A.P. Firsov, I.N. Zligostev, A.V. Savluk, A.Y. Bondarenko, P.A. Weisman, A.S. Kolesov and A.S. SheremetGrowth of the mineral resource base requires geological and geophysical studies in difficult-access conditions. Airborne geophysical survey is usually carried out during small-scale works. Large-scale surveys are conducted on foot. Most of Russia's territory is characterized by harsh conditions for such magnetic surveys - which is one of the main tools of geological and geophysical study of the territory. That is differentiated relief, boreal forests with thick undergrowth, stone runs, marshy tundra and so on. This increases the cost of the work. The use of large-scale airborne geophysical surveys is almost impossible for several reasons. Very high cost of using the carrier use (helicopters and planes). Detailed work requires a very low areal speed — below 10 m/s, and the high frequency of the magnetometer, above 100 Hz, which in turn dramatically reduces the accuracy of the survey. We propose to designate a special kind of low-altitude surveying at extremely low altitudes using a high-frequency magnetometer. Designed specifically for this type of surveys, our magnetometer complex has a frequency greater than 1.5 kHz, and the accuracy of the measurement system of the entire field is not less than 1 nT. The surveying complex is designed on base of light and ultralight drones. Experimental work on various objects (from archaeological to geological: burial mounds, skarn deposits, kimberlite pipes, geological mapping of volcanic and sedimentary rocks, etc.) has shown high efficiency of this survey type. High performance and low cost combined with the level of details in results, comparable to surveying on foot at high altitude flights, and exceeding it at low altitudes
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Physical Modeling of Electromagnetic Soundings for Justification of New Geological Exploration Technologies
Authors N.Y. Bobrov, V.V. Polovkov and D.A. PopovIt is shown that despite great development of algorithmic and software tools and possibilities of computers in the last decades, physical (analog) modeling retains considerable potential. It is used for the verification of calculations of electromagnetic field propagation in electrically contrast media and for testing new techniques of electrical prospecting. The results of physical modeling carried out for evaluation possibilities of TEM soundings in the regions of saline-domes tectonics are presented. The electrolytic tank equipped for joint modeling of seismic and electromagnetic soundings of complex geological media is presented. One of its tasks is obtaining experimental records for testing algorithms of joined inversion of seismic and electromagnetic data
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Synchronism of Geophysical Fields and Weather Conditions in the Near-Surface Zone of the Earth
Authors S.A. Riabova and A.A. SpivakGeophysical fields are an important integral part of our planet, which combine internal and external geospheres into a single self-regulating system. They contain information about properties and structure of geospheres. Variations of geophysical fields can judge the changing modes of geophysical processes. It is relevant for solving fundamental and applied problems of geophysics, in particular: for determination of the behavior patterns of inner and outer shells of the Earth, for prospecting and exploration of mineral resources, for description of the geodynamic activity of local zones of the earth's crust. The results of the analysis of synchronous variations of electric and magnetic fields, as well as acoustic waves in the near-surface zone of the Earth compare to the variation of weather condition. We show a synchronism of variations of these fields and atmosphere’s parameters. For the first time we mark not only synchronous, but also forward-looking developments of disturbances of the geomagnetic field. We introduce a new parameter — "reverse magnetic tipper". Variations of the "reverse magnetic tipper" in atmospheric disturbances appear more pronounced in comparison with the variations of the magnetic tipper.
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The Middle Ob’ Oils (West Siberia): the Geochemical Peculiarities and Genesis
More LessThe work generalizes the results of geochemical studies of Middle Ob’ oils (West Siberia) from Mesozoic deposits. Features of physicochemical and hydrocarbon (HC) composition showed the studied oils are mainly aquagene genesis. These oils are most likely to have be derived from mature organic matter of the Bazhenovo Formation. The differences observed in the studied oils can be explained by differences in biogeochemical facies of the Bazhenov Sea (the oxidation-reducing conditions of diagenesis, hydrodynamics and salt regime of the sea basin, the biota). On the other hand, the vertical migration of oil components from source-rock stratum J1-2 with mixed composition of OM can not be excluded. The strong contrast of light arenes distribution suggests the impact of the migration processes on the composition of most of the investigated oils. In the studied sampling, two samples have been revealed GC chromatograms of the saturated fraction of which are non-separated "naphthenic" hump that does not allow the identification of n alkanes and acyclic isoprenanes. There are biodegraded oils. But biodegradation has not affected the distribution of steranes and terpanes in these oils
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Geological Descriptiveness for Specialized Methods in the Investigation of Oriented Core Samples
Authors L.A. Krasnoschekova, D.A. Cherdantseva and V.P. MerkulovThe paper deals with the problem of studying spatial anisotropy of hydrocarbon reservoirs using paleomagnetic oriented core samples. Oriented rock samples were studied using complex specialized methods which included specifications of paleomagnetic, petrophysical, lithological, morphological and microstructural sandstones features. As a result, of investigation increase in the parameters of magnetic and acoustic field fluctuations in core samples were determined. Maximum of these parameters are connected with prevalent directions of quartz grains orientation and confirm with the direction of maximum permeability sandstone reservoirs. The anisotropy data for lithological, petrophysical and filtration properties in samples from the studied deposits indicate consistency changes of these characteristics. The joint application of lithological and petrophysical methods allows to receive additional volume of geological information and use it to construct real anisotropic geological and hydrodynamic models of oil fields.
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Lithological-petrophysical characterization of Ovinparm reservoir rocks in the north-easten part of Khoreyver Depression
Authors O.V. Sivalneva, S.Y. Rudakovskaya and K.Y. OlenovaAs a result of lithological and petrophysical investigation the three main types of Ovinparm reservoir rocks were determined: 1-fracture dominated, 2-pore dominated, 3-vugg dominated. The types are defined by primary structure of biogherm framework of the dolomitized rocks. It is necessary to use the computer tomography in conjunction with standart petrophysical and lithological investigation for correct characterization of the reservoir potential.
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A new petrophysical model for acoustic hysteresis based on transverse wave velocity measurements
Authors M. Dobroka and J. Somogyine MolnarIt is well known that acoustic wave propagation under pressure is very nonlinear and the elastic properties of rocks are hysteretic, which behaviour is important for mechanical understanding of reservoirs during depletion. Pressure strongly influences the elastic parameters of rocks, thus wave velocities too. Therefore a quantitative model - which provides the physical explanation - of the mechanism of pressure dependence is required. In this paper a petrophysical model is presented which describes the connection between the propagation velocity of transverse wave and rock pressure both in case of loading and unloading phases as well as explains the mechanism of acoustic hysteresis. The developed model is based on the idea that the pores in rocks close under loading and reopen during unloading. The advantage of the model is that it is not based on simple curve fitting, but gives physical explanation for the process with three-parameter exponential equations. The model was applied with success to acoustic S wave velocity data sets measured under pressure in laboratory on sandstone samples by an automatic acoustic test system.
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