188bet zokb Merging of 3D seismic data

Summary

Merging of individual seismic datasets into a single uniform dataset is useful for structure analysis, geological modelling, and seismic attribute analysis for a large area. However, many challenges are met, both from 188bet zokb acquisition aspect to processing of data before merging. 188bet zokb authors investigate in detail 188bet zokb technical difficulties of merging data, and discuss methods to accomplish 188bet zokb goal with an emphasis on post stack seismic merging, as well as merging results from our processing of field seismic datasets.

Key words: Merging seismic data, seismic data processing, special seismic techniques.

1.    Introduction

Seismic survey data has 188bet zokb pioneering role in laterally extending 188bet zokb geological study area. A regional-scale seismic study, such as 188bet zokb study of a basin, may face a stiff challenge where 188bet zokb area is so vast that it might not be coverable by a single seismic survey. In order to do so, 188bet zokb ability to combine and blend information from individual surveys becomes necessary.

Nowadays, a number of  3D  seismic  surveys has been carried out each year on 188bet zokb continental shelf of Vietnam with a typical coverage area ranging from about 100km2 to 3,500km2, usually within a study block. 188bet zokb division of 188bet zokb continental shelf into blocks and assignment to different operation companies also implies that each 3D seismic survey is limited to 188bet zokb block operated by a company. A regional-scale geological assessment, therefore, will be very difficult since 188bet zokb data is a collection of patchy seismic surveys that often have different acquisition characteristics and thus distinctive recorded seismic data characteristics.

Certainly, reacquiring seismic data for 188bet zokb whole region and processing 188bet zokb data as a large single seismic dataset may solve part of 188bet zokb problem of patchy data. However, this is unrealistic and prohibitive due to expensive costs and long computation time, not to mention 188bet zokb regional administrative problems as well as difficulties with 188bet zokb survey design phase to comprehensively cover various local structures’ orientation. A more feasible alternative is to merge available “small” overlapping 3D vintage seismic data into a single dataset with uniform amplitude, frequency, and phase. A merged seismic dataset should provide a reasonable approximation to full area acquired/processed data at a much economical cost and shorter operation/processing time.

In fact, seismic data merging has been performed regularly on many foreign projects [1 - 3] and 188bet zokb results have been very encouraging. Figure 1 shows an example map of several overlapping surveys in India [1] subjected to 188bet zokb merging process.

There are several important applications of merged seismic data. 188bet zokb subsurface image of regions near 188bet zokb edges of a local survey is usually distorted from 188bet zokb migration due to 188bet zokb deficiency of input seismic data, which eventually can be compensated by another overlapped survey data [1]. 188bet zokb most important application is probably 188bet zokb ability to carry out 188bet zokb interpretation of structures continuously and seamlessly on 188bet zokb merged seismic data from one local region to another, and hence enable many geological analyses for a large area such as 188bet zokb structural analysis, sequence stratigraphy analysis, etc. Moreover, many attribute extraction applications can also be performed on 188bet zokb merged dataset such as various seismic attribute analyses, PaleoScan software, etc.

2.    Technical difficulties with merging seismic data

188bet zokb process of merging seismic data is basically related to 188bet zokb compensation for 188bet zokb differences in seismic characteristics of various overlapping datasets. 188bet zokb variation in seismic characteristics between datasets can broadly be categorised  as coming from 2 major sources: 188bet zokb widely varying seismic acquisition configurations and 188bet zokb differences in processing technologies. We will discuss 188bet zokb effect of each type of variations on 188bet zokb seismic characteristics as follow.

    Effect of variations in acquisition schemes

Each seismic survey is usually designed with a specific goal suitable for a particular local region. Thus, different seismic surveys in nearby regions may have different acquisition parameters. We concentrate on a few important acquisition parameters.

Figure 2. Drastic amplitude differences between two overlapping surveys

Figure 3. 188bet zokb impact of 188bet zokb ghost notching frequency on 188bet zokb frequency content of 188bet zokb acquired signal [4]

188bet zokb most obvious differences are due to 188bet zokb acquisition configuration on 188bet zokb survey boat such as 188bet zokb source configuration, including 188bet zokb types of 188bet zokb source - air gun, vibroseis, dynamite, 188bet zokb geometry of 188bet zokb source array, and 188bet zokb volumes of individual guns, etc. In addition, 188bet zokb variation in 188bet zokb configuration of 188bet zokb receiver side may include 188bet zokb number and length of 188bet zokb streamer cables, 188bet zokb interval of 188bet zokb receivers, 188bet zokb type of receivers such as hydrophones, velocity phones, 188bet zokb recording and sampling intervals, 188bet zokb frequency of anti-aliasing filter, etc. Those differences provide decisive impacts on 188bet zokb amplitude and frequency content of 188bet zokb acquired seismic data, 188bet zokb signal to noise ratio (SNR), as well as 188bet zokb fold density at local common middle points. Drastic amplitude differences between two overlapping surveys can be seen in Figure 2.

188bet zokb frequency content differences may come from another source. Nearby surveys may have different source depths and receiver  depths  that  can affect 188bet zokb ghost frequencies. Typically, 188bet zokb ghost notch frequency is related to 188bet zokb source or receiver depth by 188bet zokb formula [4]

Where Vwater is 188bet zokb seismic velocity in 188bet zokb water medium, d is 188bet zokb depth of 188bet zokb  source  or  receiver and fnotch is 188bet zokb notching frequency. 188bet zokb effect of 188bet zokb ghost notch on 188bet zokb frequency content is illustrated   in Figure 3.

188bet zokb frequency limitation by 188bet zokb ghost notches, in turn, will affect 188bet zokb signal frequency bandwidth, which will impact 188bet zokb seismic resolution as well as 188bet zokb wavelet shape. Seismic frequency content and resolution differences, as a combination of several factors, can be seen in Figure 4 where 188bet zokb survey on 188bet zokb left has a much lower frequency content and resolution, comparing with 188bet zokb survey on 188bet zokb right.

New acquisition advancements such as PGS’s GeoStreamer/GeoSource [5, 6] or CGG-Veritas’ BroadSeis [7] technologies will further widen 188bet zokb seismic frequency bandwidth/resolution differences comparing to 188bet zokb seismic data acquired from 188bet zokb traditional hydrophone - flat cable configuration.

188bet zokb   presence   of   external    factors    such   as acquisition time (tidal change), changing weather (rough vs quiet sea for marine acquisition), changing unconsolidated layer thickness (for land acquisition) might result   in another class of problems which is 188bet zokb differences in phases and statics between overlapping surveys. 188bet zokb phase/static differences are troublesome for interpretation horizons to align from a seismic dataset to another. 188bet zokb effect and correction for phase/static problem is discussed further in Section 3.

Figure 4. 188bet zokb difference of 188bet zokb signal frequency bandwidth/resolution

Figure 5. Location map showing 188bet zokb Grid orientation and Master grid

A parameter that is also frequently changing from survey to survey is 188bet zokb acquisition azimuth/ orientation. This leads to 188bet zokb differences to 188bet zokb orientation of 188bet zokb migration grid (inline-crossline grid) in 188bet zokb post-acquisition seismic processing workflow. A typical 3 survey overlapping grid configuration is shown in Figure 5. As we can  see, each grid system has a different inline orientation, as well as different grid binning dimensions, not to mention 188bet zokb possible CMP- fold differences.

188bet zokb discrepancy in 188bet zokb grid orientations eventually leads to 188bet zokb need to re-grid seismic datasets in to a common encompassing grid system (master grid) and re-number 188bet zokb inline and crossline during 188bet zokb seismic merging process (Section 3).

A less obvious effect of 188bet zokb differences in 188bet zokb sail-line’s direction is related to 188bet zokb amount of seismic illumination. For a single survey orientation, underground geological objects may have certain seismic features being illuminated better than other depending on 188bet zokb alignment of 188bet zokb object and 188bet zokb sail-line’s direction. This can be illustrated in Figure 6 where, as part of 188bet zokb survey design process at 188bet zokb VPI, we simulate 188bet zokb seismic illumination of a target horizon/ fault under different sail-line azimuths of 188bet zokb survey boat with other acquisition parameters kept 188bet zokb same. As we can see a major fault is illuminated differently under different sail-line orientation. 188bet zokb differences in 188bet zokb amount of seismic illuminations on 188bet zokb same geological object mean that 188bet zokb images of 188bet zokb same object on 188bet zokb final overlapping seismic cube may have different apparent, amplitude and image quality, which requires 188bet zokb amplitude conditioning before merging.
 (a)    (b)    (c)

Figure 6. Different seismic illumination on 188bet zokb same fault depending on 188bet zokb sail line azimuth: a. 168 degree, b. 258 degree, and c. 319 degree. Illumination by 188bet zokb 258 degree sail lineazimuth appears to create 188bet zokb clearest observation of 188bet zokb fault surface.

    Differences in seismic data processing routines

188bet zokb differences in processing workflows from various contractors should also present some problems with merging seismic surveys. Each processing jobs may have dramatically different objectives, and technologies including:

-    Different target objects that may lie at different depth (shallow vs. deep).

-    Different technologies used in 188bet zokb process, such as PSTM, PSDM, and CBM, etc.

-    Different parameters used in 188bet zokb flows (possibly on 188bet zokb same dataset).

We highlight some major aspects, including phase/static, amplitudes, frequencies, and SNR, that 188bet zokb differences impact 188bet zokb merging process.

A common issue is related to 188bet zokb misalignment of events between two overlapping  datasets,  also   known   as 188bet zokb static/phase problem. Beside those originated from 188bet zokb survey configuration differences, 188bet zokb causes of 188bet zokb misalignment might also be traced to several processing routines:

-    188bet zokb difference in velocities used in 188bet zokb seismic migration might lead to some events (dipping reflection planes) to be migrated to a different time/depth comparing to one processed from 188bet zokb other routine.

  -    188bet zokb misalignment may also come from 188bet zokb differences between 188bet zokb time and depth migration, and 188bet zokb dipping features may not align for 188bet zokb PSTM and PSDM converted to time.

-    Another source of misalignments is from 188bet zokb different level of Q-compensation between datasets - leading to different phase shifts.

- Events at 188bet zokb edges of a survey is usually observed to  have  incorrect  imaging  time/depth  due to 188bet zokb insufficient input seismic points for 188bet zokb migration.

Figure 7. Seismic event misalignments of two seismic survey

Figure 8. Technology differences comparison - FX Migration vs PSTM Migration

Figure 9. Technology differences comparison - PSDM vs CBM

 Figure 10. Combination of 188bet zokb differences in seismic acquisition and processing may result in two overlapping seismic sections (left and right) with completely different appearances

Seismic event misalignments are serious because in case you are willing to align those events at a certain depth, events at other depths may still misalign.

Another discrepancy is about 188bet zokb amplitude between overlapping seismic data. Beside 188bet zokb cause from 188bet zokb acquisition configuration  factors (as discussed above), 188bet zokb variation in 188bet zokb seismic amplitude might be 188bet zokb consequence of 188bet zokb difference in migration apertures (each image point receives contributions from a varying number of traces). 188bet zokb processing flow may further contribute to it by various amplitude compensation such as 188bet zokb post stack time-variant scaling, Automatic Gain Control. Amplitude compensation for 188bet zokb absorption (Q-compensation) might be different in workflows from different processing contractors.

Thedifferences in 188bet zokb amount of Q-compensation might also be 188bet zokb source of differences in 188bet zokb frequency content of two overlapping surveys. Besides,  frequency  manipulation  techniques  such as spectral shaping, spectral whitening, spectral bluing, source deconvolution, and source wavelet de-ghosting, etc. might affect 188bet zokb frequency content between two datasets. However, for 188bet zokb marine data, these  drastic  frequency-altering  techniques   are not usually offered by 188bet zokb processing contractor to preserve 188bet zokb original frequency bandwidth (unless requested by 188bet zokb client).

An often-overlooked aspect is 188bet zokb merging of datasets with different SNR, which might make 188bet zokb final results look synthetic (a poor dataset is stitched to a good dataset). Newer computing hardware resources enable more advanced processing/ imaging algorithms that can provide seismic results with enhanced SNR and new seismic features shown up comparing to 188bet zokb vintage. 188bet zokb example shown in Figure 8 is 188bet zokb comparison of 188bet zokb seismic quality from results processed by 188bet zokb old FX migration in 2001 (left) and reprocessed by 188bet zokb PSTM algorithm in 2002, in which, 188bet zokb quality of PSTM seismic data is significantly improved, in terms of details (resolution) and frequency bandwidth, compared to 188bet zokb old (possibly obsoleted) FX migration seismic data.

Figure 9 illustrates another comparison between 188bet zokb old PSDM and 188bet zokb newer CBM processing, where many features, such as faults, top basement show up more clearly on 188bet zokb final CBM stack section, comparing to 188bet zokb vintage PSDM processing. Overlapping seismic datasets with different level of SNR will cause difficulties in matching up data, or lining-up events. A possible remedy is to perform seismic enhancement for poor quality data such as one described in a recent study from our group [8], although 188bet zokb results might be limited after stacking has been performed. Or better, input seismic data might be inspected before merging to select those with similar SNR.

188bet zokb accumulation effect of various types of differences from 188bet zokb survey configuration to seismic signal processing may result in seismic sections of 188bet zokb overlapping region with significant different appearances such as one in Figure 10. In this case, a decision will need to be made regarding 188bet zokb merge border, which, in turn, will decide which part of 188bet zokb individual survey will remain in 188bet zokb merged dataset, and which part will be thrown away.

3.    Merging 3D post-stack data

188bet zokb goal of 188bet zokb merging of 3D post-stack seismic surveys is to create a single 3D seismic cube which balances 188bet zokb phase and amplitude of individual stacked input seismic cubes. For geological structure and seismic attribute analysis, 188bet zokb results might be adequate, but certainly cannot be as good as merging pre-migration seismic data. 188bet zokb workflow can be summarised in 5 major processing steps as shown in Figure 11. Note that 188bet zokb flow chart is over-simplified and each major step can be rerun as needed.

    Regrid of seismic data

As discussed in Section 2, due to 188bet zokb differences in survey orientations, overlapping surveys may have different migration grids with different azimuths and different CDP spacings. Re-gridding of seismic data is essentially spatial  resampling   (i.e.   interpolation) of data by points on a common encompassing  master  grid  (Figure  5).  In our experiences, 188bet zokb selection of 188bet zokb master grid may fall into one of 188bet zokb two popular choices:

-    We can select 188bet zokb orientation of 188bet zokb majority of 188bet zokb surveys, which has  188bet zokb benefit of having a smaller number of surveys to be regridded.

-    Or we can select 188bet zokb orientation of 188bet zokb master grid to be orthogonal to 188bet zokb major fault or features of concern.

Figure 11. Five major steps flowchart in merging post-stack seismic data

Various interpolation schemes exist such as bilinear interpolation, bicubic interpolation, polynomial  interpolation or spline interpolation, etc. We chose 188bet zokb sinc function interpolation (Whittaker- Shannon interpolation) since it is 188bet zokb perfect reconstruction of 188bet zokb original (continuous) signal according to 188bet zokb Shannon sampling theorem [9]. In one dimension, 188bet zokb interpolation takes 188bet zokb form of:

Where t is 188bet zokb continuous time/ space variable, sinc(t) = sin(πt)/(πt) and T is usually 188bet zokb sampling rate that gives 188bet zokb samples {x[n]}. From 188bet zokb interpolation formula,  resampling   simply   means  to choose to resample t at a different discrete rate: t = T1, 2T1,…, nT1,… In our case of spatial resampling, we use 188bet zokb extended 2D version of 188bet zokb formula. An illustration of re-gridding can be seen in Figure 12 where spatial data points that misalign with 188bet zokb master grid are resampled into points on 188bet zokb master grid (located at 188bet zokb centre of each new cell).

    Amplitude conditioning

Amplitude equalisation between overlapping seismic dataset usually means correcting 188bet zokb amplitude envelopes of one dataset to match with that of 188bet zokb other one. Since there could be different gain functions applied to 188bet zokb datasets, 188bet zokb amplitude correction is usually time-variant too. Figure 13 illustrates  188bet zokb  results  from amplitude conditioning where 188bet zokb amplitude of 188bet zokb left section is matched to 188bet zokb one on 188bet zokb right section. Care has been taken to preserve relative amplitude so that seismic anomalies (such as Direct Hydro Carbon Indicator (DHI)) still show up correctly after amplitude conditioning, as 188bet zokb amplitude conditioning step only applies a constant smooth gain function (for 188bet zokb most part of 188bet zokb merging seismic cubes). As illustrated in Figure 14, a bright spot remains relatively standing out after amplitude conditioning.

Figure 12. Basemaps grid point before and after re-gridding

Figure 13. Two merging seismic sections before and after amplitude conditioning
(a)    (b)

Figure 14. A stack section with a bright spot before (a) and after (b) amplitude conditioning. Notice 188bet zokb range of amplitude of 188bet zokb original seismic is about -4e5 to 4e5, while 188bet zokb range of amplitude of 188bet zokb merging seismic is about -4 to 4. 188bet zokb bright spot has a relatively high amplitude in both cases.

   Figure 15. Average amplitude spectra from different campaigns [10]

    Frequency conditioning

Some special regions may require frequency conditioning due to 188bet zokb obvious differences in 188bet zokb frequency spectra. Thus, 188bet zokb frequency conditioning step aims to minimise 188bet zokb difference in amplitude spectra (rather than 188bet zokb energy in 188bet zokb different section). This is usually accomplished by a matching or shaping filter.

188bet zokb process of frequency matching may contain an inherent conflict goal. On 188bet zokb one hand, we want uniform frequency bandwidth on 188bet zokb merged cube for 188bet zokb attribute analysis on 188bet zokb final result and 188bet zokb easiest way is to choose 188bet zokb seismic cube with 188bet zokb lowest frequency bandwidth as 188bet zokb reference and band-limit 188bet zokb frequency of other higher-quality cubes. Certainly, this approach will degrade 188bet zokb quality of some input seismic. On 188bet zokb other hand, we also desire to preserve as much frequency bandwidth/time resolution as possible, this implies to use 188bet zokb seismic cube with wider bandwidth as 188bet zokb reference and to perform shaping filter to enhance 188bet zokb frequency content of 188bet zokb seismic data with lower bandwidth (whitening 188bet zokb data). However, 188bet zokb result might be limited as whitening 188bet zokb data too much will amplify 188bet zokb noise. In drastic cases, a decision on a compromise frequency bandwidth might be made.

An example of performing frequency conditioning can be seen in Figure 15 [10] where 188bet zokb authors apply spectral whitening to smooth out frequency spectra across 188bet zokb datasets.

Figure 16. Two merging seismic sections before and after static conditioning

188bet zokb differences in 188bet zokb amount of Q-compensation might be another aspect that is crucial to 188bet zokb discrepancy in 188bet zokb frequency content on 188bet zokb deeper section. Thus, techniques such as to apply inverse Q-compensation  and  reapply  an equal amount of Q can also be carried out if information from 188bet zokb processing report is available.

    Static/phase conditioning

This  step  is  to  match  188bet zokb  timing  and  phase  of reflection events on 188bet zokb overlapping region. Static/phase conditioning is crucial to merging and responsible for 188bet zokb smooth/seamless look of 188bet zokb merged cube. In 188bet zokb actual processing, 188bet zokb first thing to consider is to make sure all seismic dataset has 188bet zokb same polarity. This is usually obvious by inspecting major events. Optionally, performing Q-conditioning on 188bet zokb phase, again, might also be helpful to improve alignments of events on 188bet zokb deeper sections.

Static/phase conditioning, then, try to align events by 188bet zokb sub-sample levels. Techniques to estimate 188bet zokb amount of misalignment may include 188bet zokb time correlation or 188bet zokb phase spectra matching. This conditioning step then adjusts 188bet zokb data by static shifts and phase rotation. In our experiences, events at  188bet zokb outermost edges might not be easily matched due to 188bet zokb migration distortion, but they are usually discarded anyway in 188bet zokb next step.

Figure 16 shows 188bet zokb effect of matching 188bet zokb statics from two different datasets. As we can see, major events can be matched and, hence, run continuously between 188bet zokb two surveys. However, 188bet zokb result is not perfect as some small residual artifacts of 188bet zokb borders remain. This is 188bet zokb basic limitation of performing merging  on 188bet zokb post-stack dataset as static/phase conditioning may not be able to match  all events from 188bet zokb shallow to 188bet zokb deeper intervals.

    Stitching final results

188bet zokb last step is to merge conditioned seismic cube together. This involves border design and throwing away redundant seismic data (as shown in Figure 10). 188bet zokb usual added benefit is that discarded seismic is usually 188bet zokb data at 188bet zokb edges of 188bet zokb surveys where major distortions occur.

4.    Field data results

We present field data results from 188bet zokb merging process performed at EPC-VPI. Some more merging results are shown in Figure 17 where we had a seismic section before and after 188bet zokb merging process. As we can see, events are continuous and 188bet zokb whole merged section has a uniform amplitude, giving 188bet zokb perception of a dataset from a single seismic acquisition. 188bet zokb continuity of 188bet zokb events can be further illustrated in Figure  18  where  we took a time slice before  and  after  188bet zokb merging. In this case, after merging, 188bet zokb border disappears and events are continuous from one side of 188bet zokb border to 188bet zokb other side.

Figure 17. Two merging seismic sections before and after merging process

Figure 18. Time slice of two merging seismic sections before and after merging process

Figure 19. RMS analysis on 188bet zokb merged seismic cube

We also attempted to run an RMS seismic attribute extraction from 188bet zokb merged seismic cube on a horizon within 188bet zokb Oligocene layer and 188bet zokb result is successful (Figure 19). 188bet zokb attribute map looks continuous throughout 188bet zokb merge borders, allowing an interpretation of features and abnormal amplitudes, although some minor artifacts from a very small overlapping area (low fold edge region) may remain.

5.    Towards 3D premigration pre-stack seismic data merging

As we have seen in Sections 3 and 4, 188bet zokb problem of misalignments of seismic events can be partially solved by matching phase/static from post-stack seismic cubes (Section 3.2). However, residual artifacts are frequently observed, especially on 188bet zokb dipping events. This problem can only be solved completely by performing a merge on 188bet zokb premigration pre-stack seismic data (merging before imaging) such as 188bet zokb studies in [10 - 13].

Technically, reprocessing and merging from raw data should provide a better result due to 188bet zokb combination of a common processing/conditioning routine, a common velocity analysis, a common migration grid, and a common migration algorithm. 188bet zokb advantages of 188bet zokb premigration- prestack merge results comparing to 188bet zokb post-stack merge results can be shown in Figure 20 [13] where results from 188bet zokb premigration-prestack seismic merging show significantly more details in 188bet zokb overlapping region due to 188bet zokb added complementary data for migration. Another illustration is shown in Figure 21 [14] from Sino Geophysical with similar observations.

Many issues that have been discussed in Section 2 may remain with premigration-prestack data merging such as 188bet zokb discrepancies in 188bet zokb shot records such as shot length, shot density, or receiver intervals, cable length which can be solved by 188bet zokb shot record regularisation. Another discrepancy might be related to 188bet zokb CDP folds (midpoint density) and require a CDP fold regularisation also. Usually, trace regularisations (such as 188bet zokb shot record or cdp fold regularisation) can be accomplished by 188bet zokb combination of 188bet zokb trace decimation and 5D trace interpolation.

Old post stack merging section                                                                         New prestack merging section by WEFOX

Figure 20. A comparison of post-stack and pre-stack merging [12]  

Figure 21. A comparison of post-stack and pre-stack merging [14]

Pre-stack merging of seismic data will be very  useful for pre-stack analyses such as AVO and inversion analyses, although at 188bet zokb cost of some serious technical difficulties. Common sense indicates that 188bet zokb process of merging premigration data requires huge processing resource requirements (machines and workforces), a long processing time, and a high cost. Various issues like seismic illumination and frequency bandwidth might still be present.

6.    Conclusions

3D merging of seismic surveys recorded in different acquisition processes with various acquisition geometries, orientation and processing workflows is a very intricate process. Major problems are 188bet zokb mismatch of amplitude, frequency bandwidth, static/phases and SNR between overlapping seismic dataset. Fundamentally  resolving each problem is necessary to achieve 188bet zokb goal of treatment and help 188bet zokb interpreters to meet 188bet zokb geological objectives. Our hunt for 188bet zokb solutions has resulted in an in-house merging workflow for 188bet zokb post-stack data that is relatively fast to execute and cheap to implement on 188bet zokb available computing hardware. Results processed at 188bet zokb Vietnam Petroleum Institute (VPI) show a sufficiently good merged dataset that meets 188bet zokb requirements of uniform amplitudes/frequencies/phases, with a seamless look of 188bet zokb sections/time slices, and reflection events running continuously from one area to another. Our resultant merged datasets thus look quite promising that they  could be used for seamless geological interpretation or continuous seismic attribute analysis. 188bet zokb limitations of 188bet zokb post-stack merging process including some dipping events might not be to align very well, some artifacts may remain due to small overlapping area (low fold at 188bet zokb edge/ migration distortion), and sometimes high-quality data may need to be downgraded to match low-quality data. Those imperfections, although looking minor, sometimes may have serious consequences in applications such as ambiguity in interpretation or producing seismic anomaly in attribute analysis, thus extreme care must be taken both during 188bet zokb process of performing post-stack seismic merging and during QC and recommendations, as well as during actual usage.

Looking towards 188bet zokb future, we would like to explore 188bet zokb implementation of a 3D prestack-premigration merging workflows, which should promise better, more uniform, more seamless merging results, although at a possibly much more expensive computational cost, more complex algorithms/workflows and longer run time.

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10.    Bera. Prestack 3D land data merging a case history from south Asian shelf India. SPG India - 11th Biennial International Conference and Exposition. 2015.

11.    Wang Lixin. 188bet zokb pre-stack merging imaging techniques and its applications. SEG Technical Program Expanded Abstract. 2010: p. 2870 - 2874.

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13.    A.K.Srivastav, C.Chakravorty, K.V. Krishnan. Some issues in 3D Pre-stack merging. 8th Biennial International Conference & Exposition on Petroleum Geophysics. 2010.

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