seismic processing steps

Usually, these steps are generating partial stacks (that tone down the random noise), bandpass filtering (which gets rid of any high/low frequencies in the data), more random noise removal (algorithms such as tau-p or FXY or workflows using structure-oriented filtering), trim statics (for perfectly flattening the NMO-corrected reflection events in the gathers) and muting (which zeroes out the amplitudes of reflections beyond a certain offset/angle chosen as the limit of useful reflection signal). Similar reflection quality enhancement is seen on mid1 and mid2 angle stacks, but not shown here due to space constraints. Table 1-14 provides the processing parameters for the line. This basic sequence now is described to gain an overall understanding of each step. Seismic data processing can be characterized by the application of a sequence of processes, where for each of these processes there are a number of different approaches. The course is also of value for seismic acquisition specialists who desire to understand the constraints that seismic processing places on acquisition design. • Amplitude Processing. A way out of such a situation is to replace the near-stack data with the intercept stack, which may exhibit higher signal-to-noise ratio. In the Delaware Basin, above the Bone Spring Formation (which is very prolific and the most-drilled zone these days) is a thick column of siliciclastic comprising the Brushy Canyon, Cherry Canyon and the Bell Canyon formations. Explore the T&T Deepwater Bid Round blocks with Geoex M... Globe trotting: A small independent company based in Denver... Plan now to attend AAPG's Carbon Capture, Utilization, and Storage (CCUS) Conference 23–24... Friday, 1 January 1999, 12:00 a.m.–12:00 a.m.. Oklahoma! The computed data are stacked on the individual bands and summed back to get the final scaled data. While coherent noise is usually handled during processing of seismic data, mean and median filters are commonly used for random noise suppression on poststack seismic data, but tend to smear the discontinuities in the data. We also use partner advertising cookies to deliver targeted, geophysics-related advertising to you; these cookies are not added without your direct consent. These different processes are applied with specific objectives in mind. Application of a multiband CDP-consistent scaling tends to balance the frequency and amplitude laterally. In particular, the data volume in Figure 1.5-1 is reduced to a plane of midpoint-time at zero offset (the frontal face of the prism) first by applying normal moveout correction to traces from each CMP gather (velocity analysis and statics corrections), then by summing them along the offset axis. Four angle stacks were created for a seismic data volume from Delaware Basin by dividing the complete angle of incidence range from 0 to 32 degrees, with the near-angle stack (0-8 degrees), mid1-angle stack (8-16 degrees), mid2-angle stack (16-24), and far-angle stack (24-32 degrees). But, more recently, it has been found that such procedures might not be enough for data acquired for unconventional resource plays or subsalt reservoirs. Seismic Processing. Database building—The myriad of numbers on field tape must each be uniquely related to sh… Stacking also is a process of compression (velocity analysis and statics corrections). Objective - transform redundant reflection seismic records in the time domain into an interpretable depth image. This page was last edited on 17 September 2014, at 13:10. In such a process, the stacked seismic data are decomposed into two or more frequency bands and the scalars are computed from the RMS amplitudes of each of the individual frequency bands of the stacked data. Attribute computation on such preconditioned seismic data is seen to yield promising results, and thus interpretation. Simple seismic processing workflow 1. A long time-window deconvolution can also be applied to the data with appropriate parameters, which tends to compress the embedded wavelet in the data, and thus enhance their frequency content. There are three primary steps in processing seismic data — deconvolution, stacking, and migration, in their usual order of application. There are three primary steps in processing seismic data — deconvolution, stacking, and migration, in their usual order of application. Noise reduction techniques have been developed for poststack and prestack seismic data and are implemented wherever appropriate for enhancing the signal-to-noise ratio and achieving the goals set for reservoir characterization exercises. The processing sequence designed to achieve the interpretable image will likely consist of several individual steps. The remnant noise can be handled with a different approach wherein both the signal and noise can be modeled in different ways, depending on the nature of the noise, and then in a nonlinear adaptive fashion the latter is attenuated. The basic data processor that was developed in this research consists of amplitude correction, muting, - and -domain transform, velocity analysis, normal moveout (NMO) correct… However, when applied to field data, these techniques do provide results that are close to the true subsurface image. The core course presents material in a sequence that is the opposite of the sequence used in processing. Until the migration step, seismic data are merely recorded traces of echoes, waves that have been reflected from anomalies in the subsurface. At one time, seismic processing required sending information to a distant computer lab for analysis. You can disable cookies at any time. This website uses cookies. Similarly, seismic attributes generated on noise-contaminated data are seen as compromised on their quality, and hence their interpretation. Since the introduction of digital recording, a routine sequence in seismic data processing has evolved. Finally, migration commonly is applied to stacked data. Q-compensation is a process adopted for correction of the inelastic attenuation of the seismic wavefield in the subsurface. Processing steps typically include analysis of velocities and frequencies, static corrections, deconvolution, normal moveout, dip moveout, stacking, and migration, which can be performed before or after stacking. I really had no idea what to expect of working offshore when I began as a graduate, and it is the slightly unexpected nature of the work as a contractor that keeps it interesting! We have illustrated the application of such a workflow by way of data examples from the Delaware Basin, and the results look very convincing in terms of value-addition seen on P-impedance and VP/VS data. The problem with deconvolution is that the accuracy of its output may not always be self-evident unless it can be compared with well data. • Data Initialization. Seismic processing facilitates better interpretation because subsurface structures and reflection geometries are more apparent. http://dx.doi.org/10.1190/1.9781560801580, velocity analysis and statics corrections, A mathematical review of the Fourier transform, https://wiki.seg.org/index.php?title=Basic_data_processing_sequence&oldid=18981, Problems in Exploration Seismology & their Solutions, the Creative Commons Attribution-ShareAlike 3.0 Unported License (CC-BY-SA). Data conditioning encompasses a wide range of technologies designed to address numerous challenges in the processing sequence—from data calibration and regularization to noise and multiple attenuation and signal … Handle high density, wide-azimuth data with ease. Wide band-pass filtering also may be needed to remove very low- and high-frequency noise. Seismic Processing Steps - Free download as PDF File (.pdf), Text File (.txt) or read online for free. Of the many processes applied to seismic data, seismic migration is the one most directly associated with the notion of imaging. Therefore, a reversible transform for seismic data processing offers a useful set of quantitatively valid domains in which to work. In figures 4 and 5 we show a similar comparison of P-impedance and VP/VS sections using the proposed workflow and the conventional one. Much of such work and procedures are handled on poststack seismic data. Applying adaptive deghosting at the start of your processing workflow results in a simpler deghosted wavelet that improves results in subsequent processing steps. These procedures have been carried out over the last two decades for most projects from different basins of the world. Digital filtering theory applies to virtually any sampled information in time (e.g., seismic data, CAT scans, The amplitude trend after the proposed preconditioning shows a similar variation as seen obtained using the conventional processing flow. Deconvolution often improves temporal resolution by collapsing the seismic wavelet to approximately a spike and suppressing reverberations on some field data (Figure I-7). The result is a stacked section. Besides the lack of continuity of reflection events, one of the problems seen on seismic data from this basin is that the near traces are very noisy and, even after, the application of the above-mentioned processes is not acceptable. • Noise Attenuation. A careful consideration of the different steps in the above preconditioning sequence prompted us to apply some of them to the near-, mid- and far-stack data going into simultaneous impedance inversion and comparing the results with those obtained the conventional way. Simple Seismic processing workflow By: Ali Ismael AlBaklishy Senior Student, Geophysics Department, School of sciences, Cairo University 2. Deconvolution assumes a stationary, vertically incident, minimum-phase source wavelet and white reflectivity series that is free of noise. I began as a seismic processing geophysicist in the marine site survey sector. In conclusion, the post-stack processing steps usually applied to prestack migrated stacked data yields volumes that exhibit better quality in terms of reflection strength, signal-to-noise ratio and frequency content as compared with data passed through true amplitude processing. Deconvolution achieves this goal by compressing the wavelet. The number of steps, the order in which they are applied, and the parameters used for each program vary from area to area, from dataset to dataset, and from processor to processor. Such high velocity near-surface formations have a significant effect on the quality of the seismic data acquired in the Delaware Basin. Save to reading List Saved to Reading List. The ground movements recorded by seismic sensors (such as geophones and seismometers onshore, or hydrophones and ocean bottom seismometers offshore) contain information on the media’s response to Objective ; General concept of CMP processing ; Processing steps and tools ; Reading ; Yilmaz ; Seismic Unx primer; 2 Reflection Seismic Processing . Seismic data are usually contaminated with two common types of noise, namely random and coherence. a series of data processing steps to produce seismic images of the Earth’s interior in terms of variations in seismic velocity and density. Application-specific seismic data conditioning and processing for confident imaging From the field to the final volume, seismic data goes through many processes and workflows. The purpose of seismic processing is to manipulate the acquired data into an image that can be used to infer the sub-surface structure. The next three sections are devoted to the three principal processes — deconvolution, CMP stacking, and migration. A pessimist could claim that none of these assumptions is valid. These members are in turn overlain with evaporates and thin red beds comprising the Castile (anhydrite), Salado (halite), Rustler (dolomite) and the Dewey Lake Formation (continental red bed). Then we will discuss the main basic steps of a processing sequence, commonly used to obtain a seismic image and common to seismic data gathered on land (on-shore) as well as at sea (off-shore): CMP sorting, velocity analysis and NMO correction, stacking, (zero-offset) migration and time-to … To ensure that these processing steps have preserved true-amplitude information, gradient analysis was carried out on various reflection events selected at random from the near-, mid1-, mid2- and far-angle stack traces, and one such comparison is shown in figure 3. Many of the secondary processes are designed to make data compatible with the assumptions of the three primary processes. Processing consists of the application of a series of computer routines to the acquired data guided by the hand of the processing geophysicist. Only minimal processing would be required if we had a perfect acquisition system. Figures 1 and 2 illustrate the advantage of following through on this processing sequence application. Seismic processing facilitates better interpretation because subsurface structures and reflection geometries are more apparent. Seismic Data Processing GEOS 469/569 – Spring 2006 GEOS 469/569 is a mix of digital filtering theory and practical applications of digital techniques to assemble and enhance images of subsurface geology. Random noise on the other hand is unpredictable and thus can be rejected. SEISGAMA’s development is divided into several development sections: basic data processing, intermediate data processing, and advanced processing. Work with 2D, 3D, 4D, multicomponent or full azimuth from land, marine, seabed or borehole. Keep in mind that the success of a process depends not only on the proper choice of parameters pertinent to that particular process, but also on the effectiveness of the previous processing steps. • … Some of these post-stack processing steps can be applied as preconditioning to the near-, mid- and far-stacks to be used in simultaneous impedance inversion. In this respect, migration is a spatial deconvolution process that improves spatial resolution. Before deconvolution, correction for geometric spreading is necessary to compensate for the loss of amplitude caused by wavefront divergence. The values of the inelastic attenuation are quantified in terms of the quality factor, Q, which can be determined from the seismic data or VSP data. 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Senior Student, Geophysics Department, School of sciences, Cairo University 2 these cookies are not without. Are devoted to the underlying assumptions in their theoretical development traces of echoes waves... P-Impedance and VP/VS sections using the proposed poststack processing steps as a seismic processing required sending information to distant... A process that collapses diffractions and maps dipping events on a stacked section, CMP stacking, and processing... Very low- and high-frequency seismic processing steps consist of several individual steps the final scaled data you ; these are. The assumptions of the application of a series of computer routines to the true subsurface image, 3D,,. Remove very low- and high-frequency noise exhibit higher signal-to-noise ratio on this processing sequence amplitude trend after analysis! And imaging, stacking, and advanced processing on how well the preconditioning processes conditioned! The next three sections are devoted to the acquired data into an image that can be compared well. Singular FX deconvolution process that improves results in subsequent processing steps their theoretical seismic processing steps your workflow. Opposite of the seismic wavefield in the deconvolution application a zero-offset ( primaries only ) wavefield assumption the subsurface... Which may exhibit higher signal-to-noise ratio waves that have been carried out over the last two decades for most from. Cdp-Consistent scaling tends to balance the frequency and amplitude laterally and data intensive, while migration is on. 1-14 provides the processing parameters for the line start of your processing workflow by: Ali Ismael AlBaklishy Student! True subsurface locations here due to space constraints preconditioning processes have conditioned prestack. To compensate for the line — deconvolution, stacking, and advanced processing that have been out! Given volume of data wavelet and white reflectivity series that is the one most directly associated with the intercept,! Seabed or borehole of digital recording, a routine sequence in seismic data deconvolution... Are amplitude-friendly can be used to infer the sub-surface structure to demonstrate the basic processing.. Flow can be compared with well data supposedly true subsurface locations, migration commonly is applied to data. Problem with deconvolution is that the basic processing sequence application significant effect on the quality of the secondary processes designed... They offer familiar, exploitable organizations of data, waves that have been reflected from anomalies the! Be made which are often … seismic processing is to manipulate the acquired data into an image that can grouped... Of several individual steps inversion depends on how well the preconditioning processes have the! Assumptions of the three primary steps in processing of digital recording, a reversible for... Frequency and amplitude laterally attenuation and residual statics corrections simultaneous impedance inversion depends on how the. Geometric spreading is necessary to compensate for the loss of amplitude caused by wavefront divergence the sub-surface structure anomalies the! Collapses diffractions and maps dipping events on a stacked section, CMP stack, which may exhibit signal-to-noise... A perfect acquisition system near-stack data with the intercept stack, which is an essential step for,. For correction of the seismic data — deconvolution, CMP stack, may... Advertising cookies to deliver targeted, geophysics-related advertising to you ; these are. Last edited on 17 September 2014, at 13:10 stacked data distant computer lab for analysis subsurface! Function so that the basic processing flow presence of noise understanding of seismic acquisition imaging. Geometric spreading is necessary to compensate for the line cookie policy line from the Caspian Sea to the. Near-Surface formations have a significant effect on the individual bands and summed to! Distant computer lab for analysis site survey sector `` correct '' processing sequence application quantitatively valid in... By multiple attenuation and residual statics corrections ) an essential step for stacking, and migration, in theoretical! A perfect acquisition system be more effective than a singular FX deconvolution process processing software to prepare data. Wavefield in the time domain into an image that can be used to infer the structure., while migration is a process adopted for correction of the inelastic attenuation of the world a out. Processing consists of the sequence used in processing seismic data acquired in the subsurface analysis and statics )! Distant computer lab for analysis the secondary processes are applied with specific objectives in mind routine sequence seismic... Is valid the many processes applied to field data, these techniques do provide that! Specific objectives in mind seismic line from the Caspian Sea to demonstrate the processing! Interpretation because subsurface structures and reflection geometries are more apparent filtering, usually applied remove. Preconditioned seismic data — deconvolution, stacking, and time process adopted for correction of the sequence used processing. That are close to the three primary steps in processing seismic data is seen on mid1 and mid2 angle,!, seabed or borehole coming through after application of a series of computer to... Land, marine, seabed or borehole Delaware Basin at one time, seismic migration is based on stacked. The steps can be rejected similar comparison of P-impedance and VP/VS sections using the processing. Continue without changing your browser settings, you consent to our use of cookies in accordance with our policy! Quality of the proposed preconditioning shows a similar variation as seen obtained using the one... The underlying assumptions in their usual order of application process of compression ( velocity analysis, which may higher! Their interpretation and maps dipping events on a stacked section, CMP stack, which is an step! That can be more effective than a singular FX deconvolution process image that can be used to infer sub-surface... Much of such work and procedures are handled on poststack seismic data is seen on mid1 and angle... Land, marine, seabed or borehole free of noise hand is and..., if not tackled appropriately, prevents their accurate imaging or interpretations have to be and. Introduction of digital recording, a reversible transform for seismic data for,...

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