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77th EAGE Conference and Exhibition 2015
- Conference date: June 1-4, 2015
- Location: Madrid, Spain
- Published: 01 June 2015
961 - 980 of 980 results
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Improved Imaging Inside Fractured Basement Using Broadband Technology, Offshore Vietnam
Authors Z. Zhang, J. Zhou, C.H. Chionh, J. Li and G. BoneSummaryThe oil-bearing fractured granite basement rocks are a very important and complicated hydrocarbon reservoir offshore Vietnam. In this paper, we present a case study demonstrating improvements to the fracture imaging in the Cuu Long Basin offshore Vietnam through broadband technology, which not only provides great uplift in the low frequency penetration but also makes it possible to incorporate TTI/HTI anisotropy inside the granite basement. We will review the issues with conventional data and present the new approach, the result and its importance as to the interpretation for drilling.
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Analysis of Multi Measurement Broadband Data - A Case Study from the North Sea
Authors A. Raj, O.P. Munkvold, L.P. Letki, P. Smith, A. Zarkhidze and A. CookeSummaryAs a part of the reservoir characterization and development plan for a North Sea oil field, a multi-measurement survey was acquired and processed in 2012 ( Ostmo et al. 2014 ). In order to assess the viability of such multi-measurement data for future time-lapse reservoir monitoring, a subset of the sail lines were repeated. This paper presents the results from the processing and analysis of this time-lapse experiment.
Recent advances in marine streamer acquisition and processing techniques have enabled the bandwidth restriction caused by the streamer ghost to be overcome to a greater or lesser degree. However a full 3D removal of the ghost requires measurement of the pressure wave-field and its vertical and crossline gradients. Having acquired such a dataset, we can select individual components for processing, and so compare different de-ghosting strategies and their effect on time-lapse attributes.
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An Evaluation of Pre-stack Broadband Processing Technologies Offshore Namibia
Authors L.P. Blunn, L. Hodgson, L. Saxton and B. MoseleySummaryAs the signal to noise response of conventional acquisition systems has improved, vendors have developed technologies aimed at using signal processing to mitigate the effects of the source and receiver ghosts. In 2012, a 3D exploration survey with 9m receiver tow depth and a single repeat sail-line using an 18m receiver tow depth was acquired offshore Namibia by Polarcus on behalf of Serica Energy and their coventurers, BP and NAMCOR. BP asked three vendors to process the 18m tow repeat sail-line and the nearest shot line extracted from the 9m tow dataset with both their conventional and pre-stack broadband processing sequences. In this paper we evaluate the results. All the vendor broadband workflows were successful in recovering signal in the receiver notches, and the resulting datasets all showed an increase in bandwidth. However, the evaluation also revealed large differences in phase behaviour between the vendors’ results, underlining the importance of phase corrections when broadband processing.
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Enhancing 3D Broadband Land Seismic Data with Smart Super Groups for Processing and FWI
Authors D. Neklyudov, A. Bakulin, M. Dmitriev and P. GolikovSummaryLand seismic data in Saudi Arabia is always challenging thus hindering any technique relying on pre-stack information such as for instance full-waveform inversion (FWI). While many sophisticated algorithms for noise removal exist, the greatest power remains with final stack for imaging. We show how power of stacking can be harvested to enhance raw broadband 3D land data for various pre-stack applications using smart super grouping. We design large super groups both in inline and crossline directions and devise smart stacking procedures adapted to variable spatial sampling in each direction. We demonstrate on synthetic data that at low frequencies (< 8Hz) reflections and diving waves are identical on point-source and super-group data. On real 3D broadband data, super grouping greatly enhances signal-to-noise ratio and produces data ready for FWI starting from lowest sweep frequency. Advanced stacking with complex data-driven weights can also enhance high-frequency reflection data for processing and imaging. We illustrate both of these points by applying smart shot-based super groups on a 3D seismic dataset from Saudi Arabia acquired with broadband sweep 2–90 Hz.
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Quantitative Analysis of Point Receiver 3D Seismic for Optimum and Cost Effective Survey Design, Case Study
Authors A.H. El-Emam and A. El-SabaaSummaryThe objective of this study is to develop an optimized and fit-for-purpose design for future surveys; a dense point-receiver 3D acquisition pilot has been decimated to simulate alternative acquisition geometries where advanced noise attenuation techniques have been tested.
Noise attenuation using the true receiver coordinates have addressed some of the limitations of earlier DGF methods and further improved the S/N. Additionally, surface wave analysis, inversion and modelling was effective on the attenuation of coherent noise even when aliased.
These developments in processing technology, in the context of integrated acquisition and processing design, have allowed us to redesign our acquisition geometries to be more cost-effective.
Therefore, the design of the current acquisition of Burgan field was driven by the results of this study by using single lines of the point-receivers at a denser receiver line spacing, with symmetrical source geometry. The reduction in source and receiver line intervals will not only improve the near offset distribution required to image the shallow target, but will also improve the fold per offset/azimuth/midpoint bins for better signal to noise ratio and imaging through smaller OVT dimensions.
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Sequence Stratigraphy Linked with Other Stratigraphic Disciplines - Example from Lower Devonian, Eastern Saudi Arabia
Authors H. Tourqui, N. Dossary, A. Ghazi, P. Breuer and E. LacsamanaSummaryThe Lower Devonian Upper Tawil-Jauf Formation of Saudi Arabia is a widespread siliciclastic succession composed of fluvial, tidal and shoreface deposits. The section outcrops in northern Saudi Arabia also contain carbonates. To define and predict sandstone reservoir architectures, a sequence stratigraphic analysis has been applied. Previous work proposed several sequence stratigraphic interpretations. The current study presents a new and refined interpretation, integrating ichnology, biostratigraphy and chemostratigraphy, and their relationship to diagenesis. Three main transgressive-regressive cycles are identified from cores and outcrop, and maximum flooding surfaces can be correlated at the regional scale. Ichnofabrics observed in cores give more accurate interpretation of key stratigraphic surfaces.
Palynological results provide Lochkovian to Emsian ages and show a relationship between bio-events and sedimentary cycles. Chemostratigraphic analysis from a few cored wells demonstrates that mineralogical zonation can be correlated with defined stratigraphic sequences. Common patchy concretions of ferroan dolomite are observed in the sandstones below the D3B maximum flooding surface and appear to indicate a close relationship between diagenetic processes and sea level fluctuation.
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On the Nature of the Iberia-Africa Boundary in the Gulf of Cadiz - Evidence for Transpression and Implications
Authors A. Ramos, O. Fernández, P. Terrinha, J.A. Muñoz and A. ArnaizSummaryThe SW of Iberia is currently undergoing compression related to the convergence between Iberia and Africa. Multiple contractional features have been documented both immediately west and east of the Gulf of Cadiz in recent years. Significant seismic activity reflecting mainly compression has been observed between these two domains, but the features associated to this seismicity remained elusive. This paper documents the contractional structures that provide linkage across the Gulf of Cadiz and play a major role in defining the present-day bathymetry of this area.
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Quantitative Plate Tectonic and Paleogeographic Reconstructions of the Caribbean Region
Authors A. Escalona and I. NortonSummaryIn this presentation, we show the kinematic model and paleogeopgraphic maps produced by the Caribbean Basins, Tectonic and Hydrocarbons consortium (CBTH) using the software PaleoGIS. The paleogeographic maps are built using the plate model as a template in order to reproduce the location of facies through time by integrating all available data (e.g. well, outcrop, seismic, etc). A main focus in our model has been linking the on- and offshore by understanding the timing and filling of basins, subsidence patterns and detailed reconstruction of fault families (c.f. Escalona and Mann, 2011 ).
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Structural Achitecture of the Madrid Basin from 3D Gravity Inversion
Authors A. Olaiz-Campos, A.M. Mantilla-Pimiento, A. Muñoz-Martin and G. De VicenteSummaryThe Madrid Basin is an intraplate Cenozoic basin located in the central area of the Iberian Peninsula. Basement is characterized by a wide range of lithologies, from meta-sediments to granites. Sedimentary section is associated with a carbonatic platform in Cretaceous time and with continental environments during Tertiary. During the second half of the last century 2D seismic data was acquired and some wells were drilled by several oil & gas companies. Due to the lack of refraction seismic, the geometry of the Moho is not very well-known in the area. This study presents the results of the 3D gravity inversion performed mainly to determine the configuration of the Moho. Also, the geometry of basement has been refined after the inversion. The initial model was constrained by surface geology, 2D seismic and well data. The final 3D model shows significant density variations within the basement and the presence of an intra-basement structure in the Central Iberian System.
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Classification of the Structural Landslides for the Natural Hazard Assessment
By O.M. IvanikSummaryGeological analysis of the landslide processes in regions with complex heterogeneous geological structure confirmed the priority nature of occurrence of structural landslides in rheologically different geological environments. The new classification of structural landslides with the decisive influence of destructive zones has been developed. This classification is the basis for constructing geological, physical and mathematical models of landslide slopes, and subsequent modeling of the landslide hazard based on the determination of the stress-strain state of slopes. A numerical-analytical algorithm for solving the problem in the mathematical formulation, which is based on a modified iterative boundary element method, is developed. This technic is used for the landslide hazard assessment in different areas.
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Extension and Inversion of Jurassic Hydrocarbon Source Rocks in the NE Part of the Asturian Basin, NW Iberian Peninsula
Authors H. Uzkeda, J. Poblet, M. Bulnes, J.C. García-Ramos and L. PiñuelaSummaryWe study the NE emerged portion of the Asturian Basin, a Permian-Mesozoic extensional basin (NW Iberia) partially inverted during the Cenozoic as a result of a contractional event. A geological map, a 3D model, cross sections, a structural analysis and a 3D photogrammetric study were performed. Our goal is to comprehend the relevance, relative timing and behaviour of the extensional and contractional structures formed during the tectonic events defining its current framework. A Mesozoic extensional episode characterized by fault activity, increase of thermal flow and uplift and a Cenozoic contractional episode responsible for reverse and strike-slip reactivation of old faults and generation of few thrusts and folds occurred.
The information obtained here should assist with the study of worse exposed inland parts of the basin and the seismic interpretation of offshore data. Additionally, understanding the structural configuration of the Jurassic rocks cropping out in the zone might be of interest as an analogue for hydrocarbon industry, given that some of them may be potential hydrocarbon source rocks. Additionally, unravelling their structure is essential considering the recent request for a hydrocarbon exploration permit by an oil company including this area which, in turn, belongs to a state reserve acreage for CO2 storage.
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History of Sedimentation of Kalina Suite in Azerbaijan
More LessSummaryFormation of deep-water Kalin paleobasin of lake type with complicated relief due to the presence of numerous islands was the result of these processes. The following moments were observed at that time: there are two parallel processes - erosion and redeposition of rocks, that formed both “Caucasian land area” and Absheron geoanticlinal, that initiated the formation of Absheron facies formations of PS and impacted on the heterogeneity of lithological and mineralogical composition. The ambiguity of these processes naturally reflected both on the formation of Kalina Suite and differences of structural plans fixed between Miocene and Pliocene complexes within separate areas covered by waters of this paleobasin.
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The Ager Basin (Eocene, Pyrenees, Spain) - Towards a 3D Reservoir Analog for Deltas in Foreland Settings
Authors J. Pérez-Cano, M. Zamorano, O. Oms and E. RemachaSummaryThe Eocene Ager Basin outcrops (Lleida, Spain) have been extensively studied as an example of tidal influenced deltas in compressive settings. The well-exposed outcrops provide reference field analogue for oil systems in these contexts. This Eocene record is composed by three units (Baronia, Pasarel·la and Ametlla formations) that build up the Figols Sequence. The main goal of this work is to build up a 3D model at reservoir scale. First step has been the modelling of the base and the top of this sequence. This study combines the use of Petrel software, own sedimentological data and and open-access sources (DEMs, geologic maps, ortophotographs, cross sections, seismic profiles and well from ICGC and IGME). The preliminary data show the potential use of a 3D model to improve the knowledge of this classical locality. The integration of litostratigraphic and sedimentological data is providing a robust scheme to understand the lateral relationships of facies and the geometry of sandstone bodies in detail.
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Seismic Data Up-sampling beyond Aliasing Using Polynomial Phase Signals
More LessSummaryThis paper proposes a new trace up-sampling method for seismic data. The method is based on building a local time-space model of the seismic data following some physical assumptions about its structure. The model simplifies to a superposition of second order polynomial phase signals, which are estimated using a matching pursuit algorithm. The estimated model is then used to generate traces at the desired locations. The proposed method performs up-sampling beyond aliasing thanks to the ability of its matching pursuit basis to model aliasing. It differs from Fourier-based matching methods in the inclusion of a curvature term in the matching basis. The method does not rely on priors from un-aliased part of the data to build the aliasing protection. A good signal to noise ratio is the only condition needed instead. The method is tested on real data and compared to conventional up-sampling solutions. Its performance is remarkably good particularly when it comes to up-sampling highly aliased data.
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Irregularly Sampled 3D Seismic Data Reconstruction with L1/2 Norm Regularization
More LessSummarySparse reconstruction for seismic data aims to reconstruct the missing traces from noise-contaminated or incomplete seismic datasets with a sparsity regularization. The L0 and L1 regularization are the most widely used to methods to constrain the transform-domain coefficients.However,because of the NP-hard difficulty of L0 regularization and non-sparsest solution of L1 regularization, the traditional approach can not obtain the optimal solutions to the seismic interpolation problems. We propose a novel L1/2 regularization model to solve the seismic interpolation problem and borrow the efficient iterative half-thresholding (IHT) solver from the signal-processing field to solve the proposed L1/2 regularization model. An irregularly sampled 3D seismic data with 50% randomly missing traces shows accurate reconstruction using the proposed approach. Comparison with the traditional L1 regularization also confirms the effectiveness of the proposed approach. Because of the simple and efficient implementation of IHT algorithm, the proposed approach can be conveniently used in industry.
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Matrix Completion on Unstructured Grids - 2-D Seismic Data Regularization and Interpolation
Authors R. Kumar, O. Lopez, E. Esser and F.J. HerrmannSummarySeismic data interpolation via rank-minimization techniques has been recently introduced in the seismic community. All the existing rank-minimization techniques assume the recording locations to be on a regular grid, e.g. sampled periodically, but seismic data are typically irregularly sampled along spatial axes. Other than the irregularity of the sampled grid, we often have missing data. In this paper, we study the effect of grid irregularity to conduct matrix completion on a regular grid for unstructured data. We propose an improvement of existing rank-minimization techniques to do regularization. We also demonstrate that we can perform seismic data regularization and interpolation simultaneously. We illustrate the advantages of the modification using a real seismic line from the Gulf of Suez to obtain high quality results for regularization and interpolation, a key application in exploration geophysics.
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De-aliased Seismic Data Reconstruction Using Seislet-domain Percentile Thresholding
More LessSummaryInterpolating regularly missing traces in seismic data are thought to be much harder than interpolating irregularly missing seismic traces, because many sparsity-based approaches can not be used due to the strong aliasing noise in the sparse domain. We propose to use seislet transform to perform a sparsity-based approach to interpolate seismic data with highly undersampled data based on the classic projection onto convex sets (POCS) framework. Many numerical tests show that the local slope is the main factor that will affect the sparsity and anti-aliasing ability of seislet transform. By low-pass filtering the undersampled seismic data with a very low bound frequency, we can get a very precise dip estimation, which will make seislet transform capable for interpolating the aliased seismic data. In order to prepare the optimum local slope during iterations, we update the slope field every several iterations. We also use a percentile thresholding approach to better control the reconstruction performance. Both synthetic and field examples show excellent performance using the proposed approach.
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Main Actors Analysis of the Threshold Operator in POCS Reconstruction with Curvelet Transform
More LessSummaryIn this paper,we analyse main factors of threshold operator in POCS reconstruction with curvelet transform in detail and put forward a two-parameter threshold which combines three aspects. The selection condition of threshold operator parameters is different between POCS reconstruction method using curvelet transform and Fourier transform. Synthetic seismic data tests and real data example indicate the effectiveness and applicability of the threshold operator we adopt in POCS reconstruction method with curvelet transform. What’s more,the better threshold models or other factors which affect the effectiveness of POCS reconstruction method with curvelet transform need further research.
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Dreamlet-based Interpolation Using POCS Method with L0 Norm Constraint
More LessSummaryDue to incomplete and non-uniform coverage of the acquisition system and dead traces, real seismic data always has some missing traces which affects the performance of a multi-channel algorithm, such as Surface-Related Multiple Elimination (SRME), imaging and inversion. Therefore, it is necessary to interpolate seismic data. Dreamlet transform has been successfully used in the modeling of seismic wave propagation and imaging, and this paper explains the application of dreamlet transform to seismic data interpolation. With L0 norm constraint and Projection Onto Convex Sets (POCS) method, performances of dreamlet-based and curvelet-based interpolation are compared in terms of recovered signal to noise ratio (SNR) and convergence rate. Tests on synthetic and real seismic data demonstrate that dreamlet transform-based method has superior performance to curvelet transform-based method.
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Rank Minimization via Alternating Optimization - Seismic Data Interpolation
Authors O. Lopez, R. Kumar and F.J. HerrmannSummaryLow-rank matrix completion techniques have recently become an effective tool for seismic trace interpolation problems. In this talk, we consider an alternating optimization scheme for nuclear norm minimization and discuss the applications to large scale wave field reconstruction. By adopting a factorization approach to the rank minimization problem we write our low-rank matrix in bi-linear form, and modify this workflow by alternating our optimization to handle a single matrix factor at a time. This allows for a more tractable procedure that can robustly handle large scale, highly oscillatory and critically sub sampled seismic data sets. We demonstrate the potential of this approach with several numerical experiments on a seismic line from the Nelson 2D data set and a frequency slice from the Gulf of Mexico data set.
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