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Frequency aliasing

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Proceedings Papers

Paper presented at the 2015 SEG Annual Meeting, October 18–23, 2015
Paper Number: SEG-2015-5744712
.... By low-pass filtering the under-sampled 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...
Proceedings Papers

Paper presented at the 2015 SEG Annual Meeting, October 18–23, 2015
Paper Number: SEG-2015-5857262
... Summary Broadband data allows for high-frequencies to be recovered but due to operational and efficiency reasons the cross-line bin size leaves much of these data aliased. These aliased data, either noise or the desired signal, are filtered during processing and imaging leaving either...
Proceedings Papers

Paper presented at the 2017 SEG International Exposition and Annual Meeting, September 24–29, 2017
Paper Number: SEG-2017-17724305
... ABSTRACT We propose a data-driven interferometry technique to remove low frequency aliased and non-conical surface waves in cross-spread domain. Despite insufficient sampling of the constructive regions in the cross-spread domain, the proposed approach has been designed for effective handling...
Proceedings Papers

Paper presented at the 2007 SEG Annual Meeting, September 23–28, 2007
Paper Number: SEG-2007-2344
... of the traditional filtering done during this process that will improve the performance and precision of the results. In most Kirchhoff migration implementations, a triangular smoothing filter is used to avoid high frequency aliasing along the migration operator. This filter is implemented in three steps: causal...
Proceedings Papers

Paper presented at the 2013 SEG Annual Meeting, September 22–27, 2013
Paper Number: SEG-2013-1081
... than expected frequencies and frequency aliasing. A 3-point derivative solution departs from ideal frequency response at 0.2 Nyquist while a 7-point solution departs at 0.4 Nyquist. The mitigation of these issues requires the use of a properly tapered and padded signal for calculation of the analytic...
Proceedings Papers

Paper presented at the 2008 SEG Annual Meeting, November 9–14, 2008
Paper Number: SEG-2008-2627
... filters estimated from the low-frequency (alias-free) portion of the data are used to interpolate the high-frequency (aliased) data components. Several modifications to Spitz''s prediction filtering interpolation have been proposed. For instance, Porsani (1999) proposed a half-step prediction filter...
Proceedings Papers

Paper presented at the 2008 SEG Annual Meeting, November 9–14, 2008
Paper Number: SEG-2008-3375
... of approximately 15,000 vibe points. High frequency aliasing was expected at frequencies of 145 Hz or higher for source spacing of greater than 300 ft. wamsutter field upstream oil & gas almond interval migration hornby han sugianto brian hornby interpretation main menu analysis finite...
Proceedings Papers

Paper presented at the Offshore Technology Conference, May 6–9, 1985
Paper Number: OTC-4864-MS
... into an interpretable format. Marine three-dimensional (3-D) seismic surveys traditionally have been planned and executed using rectilinear grids with line-to-line spacing sufficiently close (25 to 75 meters) to avoid spatial-frequency aliasing in the crossline direction. Designing field procedures to meet...
Proceedings Papers

Paper presented at the 1990 SEG Annual Meeting, September 23–27, 1990
Paper Number: SEG-1990-0579
... magnetometer readings through aliasing of high frequency magnetic interference. A set of standard techniques and calibrated displays was devised to allow meaningful comparison of noise levels between different magnetometer sensors, data acquisition systems and installations. INTRODUCTION Magnetometers continue...
Proceedings Papers

Paper presented at the 1999 SEG Annual Meeting, October 31–November 5, 1999
Paper Number: SEG-1999-1134
... ev en ts from the migrated image. Gra y(1992)proposed an approach whic hremoved only the frequency components that are aliased. Gra y created multiple v ersions of eac h input trace ltered with various high-cut lters. When the migration required a certain frequency limit, the ltered version...
Journal Articles
J Pet Technol 50 (01): 42.
Paper Number: SPE-0198-0042-JPT
Published: 01 January 1998
... 1998. Offshore Technology Conference frequency antialia filter geometry Reservoir Characterization node length equal noise limitation acquisition group interval attenuate nyquist limit aliased energy Upstream Oil & Gas wave-number domain noise contribute nyquist boundary...
Proceedings Papers

Paper presented at the 2008 SEG Annual Meeting, November 9–14, 2008
Paper Number: SEG-2008-2551
... SUMMARY A rigorous, explicit antialias spatial filter is designed and applied to remove energy above the first Nyquist wavenumber in the horizontal slowness-frequency domain. The antialias filter removes the spatially aliased frequencies selectively at each slowness; conventional antialias...
Proceedings Papers

Paper presented at the 2002 SEG Annual Meeting, October 6–11, 2002
Paper Number: SEG-2002-1232
... migration more than alternative schemes. The analysis covers the following topics: - Spurious Differences - Aliasing: Temporal; Spatial - Wavelet Changes During Migration: Frequency, Velocity & Offset Dependent - Kirchhoff Migration as a Stacking Process: Travel-Time Sampling Errors; Sensitivity to Velocity...
Proceedings Papers

Paper presented at the 2004 SEG Annual Meeting, October 10–15, 2004
Paper Number: SEG-2004-2013
... the interpolant using 512 Fourier coefficients. It obeys both orthogonality condition and stability condition. Moreover, it has more zero-cross points than necessary, which can be used for de-aliasing. Based on the above analysis, an adapted frequency range can be used to design the interpolants on any irregular...
Proceedings Papers

Paper presented at the 1995 SEG Annual Meeting, October 8–13, 1995
Paper Number: SEG-1995-1373
... mask the reflection events almost completely. Groundroll is characterized by low velocity and low frequency and very often shows spatial aliasing. The groundroll persists despite the shot and geophone patterns employed during data acquisition. In these situa- tions stacking fails to remove...
Proceedings Papers

Paper presented at the SEG International Exposition and Annual Meeting, October 11–16, 2020
Paper Number: SEG-2020-3421471
... Temporal aliasing occurs when a waveform is sampled with less than two points per time period for a signal at a given frequency. This insufficiently sampled frequency will incorrectly be mapped into a lower (aliased) frequency. Analog to this, spatial aliasing is said to occur when a propagating...
Proceedings Papers

Paper presented at the 2015 SEG Annual Meeting, October 18–23, 2015
Paper Number: SEG-2015-5829920
... the highest frequency content, a sparser than needed horizontal wave-propagation grid is often used to make high-frequency RTM affordable. As a result, the theoretically alias-free RTM operator suffers from aliasing issues when applied to high-frequency data with steep surface angles. To solve this aliasing...
Proceedings Papers

Paper presented at the Abu Dhabi International Petroleum Exhibition and Conference, November 3–6, 2008
Paper Number: SPE-117915-MS
... applied to the separate hydrophone and geophone data sets before PZ summation were effective in removing a significant amount of noise. However remnant noise was still present after PZ summation. This noise included high-frequency residual aliased water-borne noise, receiver coupling and remnant coherent...
Proceedings Papers

Paper presented at the 1995 SEG Annual Meeting, October 8–13, 1995
Paper Number: SEG-1995-0041
..., synchronizing the free-running signatures with the seismic source, filtering out unwanted frequencies for improving S/N ratio, and preventing frequency aliasing. The beauty and efficiency of the method are reflected by the fact that these multiple functions are achieved 41 2 Downhole seismic data acquisition...
Proceedings Papers

Paper presented at the The 29th International Ocean and Polar Engineering Conference, June 16–21, 2019
Paper Number: ISOPE-I-19-673
... the auxiliary noise analysis method with the frequency analysis method to eliminate the modal aliasing. The modified EMD method is applied to the shock response signal analysis. By studying each eigenfunction, the components and characteristics of shock response acceleration signal are analyzed, which provides...

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