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Collaborating Authors
Results
Summary A two-dimensional finite-difference modelling program with an accurate free surface representation was used to model dynamite style records. The results depict the recording of near surface effects and their relationships to the recording of body waves. For body waves, the source ghost is shown to cause an approximate derivative wavelet, where the precise phase rotation depends on the depth of the source. The character of the first breaks is shown to depend on the near surface velocity profile, affecting their amplitude, arrival time, and dispersion. The dependence increases as the offset increases. In many cases the effect of the surface ghost and offset dependence of the first breaks can appear to give contradictory polarity results. Model snapshots use new colour codes to distinguish energy types.
- Geophysics > Seismic Surveying > Seismic Modeling > Velocity Modeling (0.36)
- Geophysics > Seismic Surveying > Seismic Processing (0.31)
Summary The seismic data have to be zero phase. The ''Sparse Layer Transform'' cannot resolve seismic interference/tuning below the seismic resolution (1/2 of the dominant period). The ''Sparse Layer Transform'' is a simple algorithm for transforming seismic data into a sparse layer model of relative impedances. It is closely related to traditional trace integration (so-called bandlimited inversion), based on the same basic assumption and with the same main limitation:The one iteration ''Sparse Layer Transform'' exhibits a performance slightly below that of traditional trace integration, whereas the two iteration implementation typically performs as good as traditional trace integration.
Summary The standard approach for estimating the fluid factor is flawed because intercept and gradient are statistically correlated. This pitfall is difficult to identify because the statistical correlation bears a strong resemblance to the expected lithologic correlation. As a result, the estimated fluid factor reduces to a far-angle stack. An alternative approach uses uncorrelated near- and far-angle stacks to compute the fluid factor. It takes advantage of the very definition of the fluid factor as the perpendicular to the background trend to decouple lithologic and statistical trends.
- Geophysics > Seismic Surveying > Seismic Processing > Seismic Migration (1.00)
- Geophysics > Seismic Surveying > Seismic Modeling > Velocity Modeling > Seismic Inversion (0.51)
- Geophysics > Seismic Surveying > Seismic Interpretation > Seismic Reservoir Characterization > Amplitude vs Offset (AVO) (0.48)
Summary It is sometimes remarked that pre-stack Kirchhoff depth migrated images have a lower frequency content than their time-domain counterparts. Here we assess the various factors that influence frequency content during migration, with the object of assessing the reasons for potential loss of bandwidth in migrated data. We demonstrate that there is no inherent reason for the bandwidth of Kirchhoff (or depth) migrated data to be worse than other migrated data, and offer recommendations for ensuring optimal frequency content in the processed output image.
- Geophysics > Seismic Surveying > Seismic Processing > Seismic Migration (0.75)
- Geophysics > Seismic Surveying > Seismic Modeling > Velocity Modeling (0.69)
Summary By adapting procedures from refraction seismology, GPR refraction methods appear promising for shallow stratigraphic studies, particularly when the structure consists of bedrock or coarse-grained unconsolidated sediments beneath partiallyโsaturated fine-grained sand, silt or organic rich soil (Bohidar, 2001, Bohidar and Hermance, 2002; Hermance and Bohidar, 2002a). Under appropriate conditions, refracted phases can be readily detected at transmitter-receiver offsets of over 15 m, and from depths of over 2 m. However, if the GPR refraction method is to realize its potential, tools need to be developed that abate some of the time-intensive labor in reducing refraction data for practical surveys. Preconditioning radargram images using non-linear gain controls are particularly effective for detecting the presence of refraction events.
Summary Observations of shear-wave splitting from converted-wave seismic surveys are becoming common. When interpreting 3-C data for shear-wave splitting, it is important to be able to distinguish true indicators of shear-wave splitting from false ones. Multicomponent exploration is in its infancy, so it is possible for geometry-related problems to exist in acquisition and processing without being recognized. Land 3-C surveys are often conducted with equipment that is designed for ordinary 1-C data. With three times the normal amount of cable to lay out and plug in, it is possible, and relatively easy, for mistakes to be made regarding which channels are recording which components.
Summary Deterministic and stochastic seismic inversions were performed integrating well, seismic and geologic data in the Rotliegend Gas Field, North German Basin, northwestern Germany, to build acoustic impedance models for reservoir property modeling. The deterministic inversion created pseudo-logs of absolute impedance values at each seismic trace location by spectrally combining the inverted balanced seismic traces and the low frequency background model about the transition frequency. The stochastic inversion built upon the work performed in the deterministic inversion and integrated the dense areal sampling of the seismic data with the fine vertical sampling of the log data utilizing geostatistical techniques to produce high-resolution acoustic impedance models.
- Europe > Germany (0.89)
- North America > United States > Texas > Dawson County (0.26)
- Asia > Middle East > Qatar > Arabian Gulf (0.25)
- Geology > Mineral (0.71)
- Geology > Rock Type > Sedimentary Rock (0.49)
- North America > United States > Texas > Permian Basin > Yeso Formation (0.99)
- North America > United States > Texas > Permian Basin > Yates Formation (0.99)
- North America > United States > Texas > Permian Basin > Wolfcamp Formation (0.99)
- (27 more...)
Summary A matching pursuit technique composed with an imaging method is used to obtain quantitative information on geological records from seismic data. The technique is based on a greedy non-linear search algorithm decomposing data into atoms. These atoms are drawn from a redundant dictionary of seismic waveforms. Fractional splines are used to define this dictionary, whose elements are not only designed to match the observed waveforms but also to span the appropriate family of geological patterns. Consequently, the atomโs parameterization provides localized scale, order and direction information that reveals the stratigraphy and the type of geological transitions. Besides a localized scaling characterization, the atomic decomposition allows for an accurate denoised reconstruction of data with only a small number of atoms. Application of this approach to angles gathers allows us to track geological singularities from seismic data.
- Geophysics > Seismic Surveying > Seismic Modeling (0.66)
- Geophysics > Seismic Surveying > Seismic Processing (0.49)
- Information Technology > Artificial Intelligence > The Future (0.81)
- Information Technology > Artificial Intelligence > Issues > Social & Ethical Issues (0.81)
- Information Technology > Data Science > Data Quality > Data Transformation (0.51)
- Information Technology > Artificial Intelligence > Representation & Reasoning (0.50)
Simultaneous Acquisition of 3D Surface Seismic And 3D VSP Data - Processing And Integration
Chopra, Satinder (Scott Pickford, Calgary) | Blias, Emil (Scott Pickford, Calgary) | Chavina, Lioudmila (Scott Pickford, Calgary) | Alexeev, Vlaidmir (Scott Pickford, Calgary) | Manerikar, Abhi (Conoco Canada Resources Ltd, Calgary) | Kryzan, Andrew (Conoco Canada Resources Ltd, Calgary)
Introduction The first 3D vertical seismic profile (VSP) acquisition was attempted in 1986 by AGIP; several 3D VSP volumes have been acquired since then[1-9]. Apart from the 3D VSP acquisition, a simultaneous VSP and 3D surface seismic acquisition has been attempted [10], and the results have been encouraging in terms of cost effectiveness and the enhanced imaging of the subsurface. This work is an attempt to describe the simultaneous acquisition of 3D surface seismic data, the 3D VSP data and to detail the different steps that were followed to process the two data volumes. Attempts were made to enhance the bandwidth of the 3D seismic data using the VSP downgoing wavefield and integrate the 3D VSP volume with surface seismic to be able to interpret the two together. Acquisition of data Simultaneous data acquisition of surface 3D and 3component 3D VSP data was carried out by Crestar Energy Ltd. (now Conoco), in October 2000 in Hanna area in Central Alberta.
- North America > Canada > Alberta (0.35)
- North America > United States (0.31)
- Europe > United Kingdom > North Sea > Northern North Sea > East Shetland Basin > Block 211/29 > Brent Field (0.99)
- Europe > Norway > North Sea > Central North Sea > Central Graben > PL 018 > Block 2/4 > Greater Ekofisk Field > Ekofisk Field > Tor Formation (0.99)
- Europe > Norway > North Sea > Central North Sea > Central Graben > PL 018 > Block 2/4 > Greater Ekofisk Field > Ekofisk Field > Ekofisk Formation (0.99)
Generalized S Transform And Its Applications For Analysis of Seismic Thin Beds
Tian, Fang (Institute of exploration and exploitation for oil, Daqing oil field limited liability company) | Chen, Shu-min (Institute of exploration and exploitation for oil, Daqing oil field limited liability company) | Chen, Wen-chao (Institute of exploration and exploitation for oil, Daqing oil field limited liability company) | Gao, Jing-huai (CGG) | Zhang, Zhi-yu (Institute of Wave and Information, School of Electronic and Information Engineering, Xian Jiaotong University) | Li, You-ming (Institute of geology and geophysics, Chinese academy of sciences)
Summary In this paper, the idea of the Stransform is developed. A generalized transform (GST) and its inversion are proposed for analyzing the seismic thin beds. In the GST, the mother wavelet has four types of parameters (amplitude, decay rate of energy, delayed time of energy and apparent frequency) to be chosen according to the object. This causes the GST to be more efficient than the ST. For demonstrating the effectiveness, some synthetic data from several typical models of the thin beds are made. Then with the synthetic data as objects, the ST and GST are used to determine the location of reflectors in the thin beds respectively. The results show that the GST has high precision but the ST does not. When being used for field data, the GST gives good results too.
- Asia > China (0.71)
- North America > United States > Utah (0.17)
- Asia > China > Heilongjiang > Songliao Basin > Daqing Field > Yian Formation (0.99)
- Asia > China > Heilongjiang > Songliao Basin > Daqing Field > Mingshui Formation (0.99)