Common Reflection Surface Stack Research Articles

Deep Seismic Reflection Imaging of Mesozoic Kachchh Rift, NW India: Implications for Evolution

AbstractDeep crustal seismic reflection profiling is carried out for first time across various tectonic domains of seismically active Mesozoic Kachchh rift basin, formed during the breakup of Gondwanaland. The seismic data, processed using the common reflection surface stack approach, provided maiden images of the shallow and deep sub‐surface structures in the region. These images reveal a 15 km thick subhorizontal lower crustal reflection fabric and crustal‐scale domal‐type structure extending from the surface to the Moho. We interpret the earlier structure represent magmatic underplating and the latter as the Kachchh Mainland uplift. We find large variations in the thickness of sediments from 150 m to 6.5 km and crustal thickness from 45 to 35 km from north to south, with a Moho up warp of 4 km beneath the Kachchh Mainland fault. The Kachchh rift basin exhibits an unusually thick crust of 45 km, contrary to many rift basins. We interpret the syn‐rifting and the Reunion mantle plume activity, manifested as Deccan volcanics, are responsible for magmatic underplating and crustal thickening. Uplift in the region is multi‐genetic in origin. Present study illuminated new faults and nature of various other faults. Moderate to large earthquakes in the region are attributed to the regional and local stresses resulting from the plate boundary and heterogeneous crustal structure. Based on the mafic lower crust and distribution of aftershocks through the entire crust, we interpret the lower crust is brittle, contrary to most models of continental rheology.

Advanced Processing of 2D Marine Reflection Seismic Data Using the Common Reflection Surface (CRS) Stack Method with K-L Filter Application

Data processing using the seismic reflection method is an important stage in the exploration of natural resources and minerals. This research was conducted to determine the effective and efficient stacking and filtering methods in reconstructing the subsurface geological structure of the earth from the results of data processing using ProMAX software. The data processing method used is the conventional stack and the Common Reflection Surface (CRS) stack. Aperture values of 0 ms – 50 m and 3000 ms – 150 m in the CRS stack process produce the most optimum seismic sections. Both methods produce a different quality of seismic cross-section display. The 2D cross-section model from the conventional stack method looks noisier than the results from the CRS stack method. In addition, the reflector pattern on the cross-section of the results of the CRS stack method is clearer and visible with a relatively large amplitude compared to the results of the conventional stack method. To maximize the quality of data display, data enhancement is applied, which is the K-L filter. The eigenimages value of 0.10% on the K-L filter with a horizontal window width of 120 is used to reduce random noise. Thus, an increase in the S/N ratio will be obtained in the seismic data so that the 2D cross-sectional model of the seismic reflection method can approach the original conditions of the subsurface geological structure.

Data reconstruction combining MWNI and CRS-based interpolation methods

Many seismic processes, such as migration, inversion, and quantitative interpretation, can be improved via multidimensional regularization and interpolation methods. Different algorithms based on signal processing principles have been proposed for multidimensional seismic data reconstruction. Similarly, the Common Reflection Surface (CRS) stack method, a technique based on ray-theory principles, can also be used for regularization and interpolation. CRS-based reconstruction requires determining the wavefront attributes of the CRS stacking operator directly from the data. These wavefront attributes are commonly searched through global optimization algorithms, where a coherence measure is maximized. The precision and reliability of the wavefront attributes (also called CRS attributes) depend on the optimization method used in their search and the quality of the input data. Onshore field data with missing traces and gaps due to missing shot records can introduce attribute errors and create artifacts that contaminate seismic stacks. To solve this problem, we propose applying the Minimum Weighted Norm Interpolation (MWNI) method for the reconstruction of the prestack data before estimating the CRS attributes. Then we use the wavefront attributes to CRS-based prestack data reconstruction and denoising. We validate the combination of MWNI and CRS-based interpolation methods with synthetic data and show that the CRS attributes extracted by the combined approach are very similar to the reference values. The proposed processing flow shows excellent results on an onshore vintage dataset from the Parnaíba Brazilian basin, where MWNI operates as a fold regularization. The reconstructed data obtained by combining MWNI and CRS show significant improvements compared to the reconstructed data using the two algorithms separately. Prestack time migration images show increased quality when the two methods are adopted in the processing flow.

Migration velocity analysis based on focusing diffractions generated from CRS wavefront attributes: Application to real land data

In land seismic data processing, the prestack time migration (PSTM) image remains the standard imaging output, but a reliable migrated image of the subsurface depends on the accuracy of the migration velocity model. We have adopted two new algorithms for time-domain migration velocity analysis based on wavefield attributes of the common-reflection-surface (CRS) stack method. These attributes, extracted from multicoverage data, were successfully applied to build the velocity model in the depth domain through tomographic inversion of the normal-incidence-point (NIP) wave. However, there is no practical and reliable method for determining an accurate and geologically consistent time-migration velocity model from these CRS attributes. We introduce an interactive method to determine the migration velocity model in the time domain based on the application of NIP wave attributes and the CRS stacking operator for diffractions, to generate synthetic diffractions on the reflection events of the zero-offset (ZO) CRS stacked section. In the ZO data with diffractions, the poststack time migration is applied with a set of constant velocities, and the migration velocities are then selected through a focusing analysis of the simulated diffractions. We also introduce an algorithm to automatically calculate the migration velocity model from the CRS attributes picked for the main reflection events in the ZO data. We determine the precision of our diffraction focusing velocity analysis and the automatic velocity calculation algorithms using two synthetic models. We also applied them to real 2D land data with low quality and low fold to estimate the time-domain migration velocity model. The velocity models obtained through our methods were validated by applying them in the Kirchhoff PSTM of real data, in which the velocity model from the diffraction focusing analysis provided significant improvements in the quality of the migrated image compared to the legacy image and to the migrated image obtained using the automatically calculated velocity model.

Research progress on seismic imaging technology

High-precision seismic imaging is the core task of seismic exploration, guaranteeing the accuracy of geophysical and geological interpretation. With the development of seismic exploration, the targets become more and more complex. Imaging on complex media such as subsalt, small-scale, steeply dipping and surface topography structures brings a great challenge to imaging techniques. Therefore, the seismic imaging methods range from stacking-to migration-to inversion-based imaging, and the imaging accuracy is becoming increasingly high. This review paper includes: summarizing the development of the seismic imaging; overviewing the principles of three typical imaging methods, including common reflection surface (CRS) stack, migration-based Gaussian-beam migration (GBM) and reverse-time migration (RTM), and inversion-based least-squares reverse-time migration (LSRTM); analyzing the imaging capability of GBM, RTM and LSRTM to the special structures on three typical models and a land data set; outlooking the future perspectives of imaging methods. The main challenge of seismic imaging is to produce high-precision images for low-quality data, extremely deep reservoirs, and dual-complex structures.

Improvement of Seismic Sections and Well Logs for Joint Geophysical Interpretation

Seismic and well-logging data are useful for comparison and then integratation for a comprehensive geophysical interpretation. In the course of this work, seismic results were compared with well-logging geophysical data and profiles for more reliable evaluation of groundwater formations in the Tokaj region, north-east Hungary. The seismic results and profiles were obtained by the Common Reflection Surface (CRS) stacking technique. This is an advantageous stacking technique that is expected to greatly improve seismic profiles. In connection with this, we also examined some well-logging geophysical profiles so that we can improve later results. By comparing and examining the two types of sections together, we provide a basis for various method developments that improve the sections. Thus, the aim is to fill in the missing data, so that the well-logging and seismic sections can be examined together as accurately as possible in order to gain a more accurate picture of the subsurface formations. It is important to determine the lithology and petrophysical characteristics using well logs. The section replacement the improvement of the units is done using machine learning-based and inversion methods such as factor analysis or cluster analysis. An important outcome in the application of geophysical inversion methods is that the results of different methods can be jointly interpreted and this can significantly increase the reliability of the results. The application of these methods and their development is expected to reduce uncertainty and ambiguity and to increase the accuracy of the sections.

Study on the Velocity Analysis Method of Low SNR Seismic Data

When the signal to noise ratio of seismic data is very low, velocity spectrum focusing will be poor., the velocity model obtained by conventional velocity analysis methods is not accurate enough, which results in inaccurate migration. For the low signal noise ratio (SNR) data, this paper proposes to use partial Common Reflection Surface (CRS) stack to build CRS gathers, making full use of all of the reflection information of the first Fresnel zone, and improves the signal to noise ratio of pre-stack gathers by increasing the number of folds. In consideration of the CRS parameters of the zero-offset rays emitted angle and normal wave front curvature radius are searched on zero offset profile, we use ellipse evolving stacking to improve the zero offset section quality, in order to improve the reliability of CRS parameters. After CRS gathers are obtained, we use principal component analysis (PCA) approach to do velocity analysis, which improves the noise immunity of velocity analysis. Models and actual data results demonstrate the effectiveness of this method.

Thick-skinned tectonics of the Achankovil Shear Zone, southern India, inferred from new deep seismic reflection image: Constraints on the East African Orogen

The East Gondwana was formed by the assembly of continental fragments, namely India, Madagascar, Sri Lanka, and Antarctica, with the evolution of 2000 km long East African Orogen around 550 Ma. Lack of knowledge on the subsurface structure of the orogen led to a wide range of evolutionary models. The present study attempts to resolve various models’ ambiguity by presenting new results of the first deep seismic reflection study across the Achankovil Shear Zone, Southern Granulite Terrain, India that was evolved during the East African Orogen. The seismic study is also the first of its kind among the east Gondwana fragments. The Common reflection surface stack images of the present study reveal hitherto unknown details along with a unique south-dipping reflection fabric extending from the surface to upper mantle depth. We interpret this fabric is formed due to subduction-accretion of Madurai and Trivandrum blocks during the East African Orogen and represents a suture zone. Two deep-seated shear zones, the Achankovil and Tenmalai were also developed at both ends of collision fabric with strike-slip characteristics. Orogenic collapse and post-orogenic extension are inferred from the subhorizontal lower-crustal reflection fabric, which is interpreted as an equilibrated younger Moho. The present study provided an opportunity to understand the formation and exhumation of granulites, which act as a window on the inaccessible lower continental crust. Gravity modelling is performed along the seismic profile. Integration of present results with the existing geological and geophysical data provided basic constraints on the structure and tectonics of east Gondwana fragments and the East African Orogen.

Improving 3D water column seismic imaging using the Common Reflection Surface method

Water column processing has gained attention in recent years since a seismic model of a water column could assist marine data processors to correctly image the sub-seafloor geology, which is the target of primary interest. In addition to seismic processing, water column imaging has gained interest in the physical oceanography community for improved study of oceanographic processes. However, seismic water column processing is challenging since the internal reflections of the ocean are inherently weak and are often masked by noise. In this work, we adopt the common reflection surface stack technique in order to improve the imaging of ocean water layers. The common reflection surface stack is a robust data preconditioning and stacking technique in seismic processing that relies on the kinematic wavefront attributes of seismic waves. The method is applied to a multichannel 3D data set collected for oil and gas exploration in the deep-water Gulf of Mexico. The method greatly improves inline sections but does not significantly enhance crosslines and horizontal slices, which are more sensitive to both the acquisition geometry and the temporal variability of ocean water masses.

Appication of ZO-CRS Stack on Residual PP Removal of PS Component in Converted-Wave Sesimic Reflection Processing

A high-quality image of the PS component is needed since applying the converted-wave seismic method has increased significantly in hydrocarbon exploration, especially in interpreting the detail and complexity of structure or reservoir zones. The incident P-wave on a surface produces a reflected and converted P-S wave. Converted-wave seismic uses the multicomponent receiver that records both vertical and horizontal components. The vertical component is assumed to correspond to the compressional PP wave, and the horizontal corresponds to the PS converted-wave. To better understand how to image better the PS component, synthetic seismic data with the shallow gas and relatively complex model are constructed by the full-waveform modeling. This study aims to improve the imaging quality in the PS section to remove the residual PP events on the horizontal data refer to our previous study. In this study, to obtain the more reliable PS data, the residual PP reflections have been removed by applying the Zero Offset Common Reflection Surface (ZO CRS) Stack of the PS component. The results of this study, the imaging quality is better than that in the previous study.

3-D seismic exploration across the deep geothermal research platform Gro\xdf Sch\xf6nebeck north of Berlin/Germany

The North German Basin is one of the three major type localities in Germany for deep geothermal energy. Here, the pore space is the dominant parameter, in contrast to fractures (Rhine Graben) and karst (Molasse Basin). To further develop the geothermal research platform Groß Schönebeck located in the Northeast German Basin, a subset of the North German Basin, we investigated the geological structure and the existence of possible fault systems in the subsurface. For this purpose, we carried out a high-resolution 3-D reflection seismic survey at the location to overcome methodical restrictions of the few 2-D seismic profiles that cross the area of interest, such as spatial focusing effects and fault imaging. The survey area extends 8 km × 8 km at the surface and focusses down to reservoir depths at 4 km. With four vibrators as source (12–96 Hz sweep, 12 s duration), we used a source line spacing of 700 m and a receiver line spacing of 400 m with both 50 m source and geophone spacing. Data processing encompassed CRS (Common Reflection Surface) stacking, post-stack time migration and depth conversion. We observed a smooth doming of the Zechstein salt from 0.6 to 1 km thickness above the continuous top of the Rotliegend Group at around 4 km depth, and the Mesozoic horizons above appear as mainly continuous reflection surfaces with gentle undulations and occasional normal faulting. We highly resolved the supra-salt sequences in the study area for the first time, which allowed us image an almost complete suite of reflectors mapped in other parts of the Northeast German Basin. However, less resolved, lower frequency images are encountered deeper than ~ 4 km. Two important factors for further field development are that we do not observe an apparent influence of crustal-scale faults, which were expected from former conceptual models for the region, and that at the current status of work, the reservoir does not show a fracture-dominated character.

Analysis of Common Surface Reflection (CSR) Methods 2D Multichannel Data in Morowali Sea Waters

One of the processes contained in this seismic data processing is Stacking. The conventional Stacking process uses CMP which is at the same midpoint point. In other words, the reflector fields that are in the same point will be combined. This process is called the NMO correction process (normal move out correction). This CRS Stack is a conventional method of CMP Stack erby using different approaches. The purpose of this study is to process 2D seismic data at Morowali Sulawesi waters using the Common Reflection Surface (CRS) method so that it gets an overview of the Morowali Sulawesi Aquatic structure. In CDP 7701782 above we can see various differences in cross-section. But in the CRS aperture operator with a value of 887.5 (far offset) and 0-0, 1000-179, 2000-416, 3000-568, 4000- 713, 5000- 48 radius of the Fresnel zone) there is no significant difference, this because basically if 5400887.5 (TWT-Aperture) TWT is between 0 to 5400 the Aperture value is between 0 to 887.5. This parameter has covered the entire area.

3D wavefront attribute determination and conflicting dip processing

The knowledge of 3D wavefront attributes allows many important applications, such as stacking, 5D interpolation, 3D diffraction separation and imaging, and 3D wavefront tomography, just to name a few. For the determination of wavefront attributes, we use the common-reflection-surface (CRS) operator. We adopt a simultaneous search for the determination of wavefront attributes and combine it with conflicting dip processing. For the simultaneous search, we compare three heuristic global optimization algorithms such as particle swarm optimization (PSO), genetic algorithm (GA), and differential evolution (DE). For conflicting dip processing, a dip angle decomposition method for the probed sample is introduced and the simultaneous search is independently performed in specified dip ranges to individually obtain attributes and semblance for each range. Results for the laterally heterogeneous 3D SEG C3WA data indicate that DE has superior performance to determine the 3D wavefront attributes when compared with PSO, GA, and the conventional pragmatic approach because a higher semblance and an improved set of wavefront attributes are achieved. A comparison of the data-driven wavefront attributes obtained from the DE with the model-driven wavefront attributes computed by kinematic and dynamic ray tracing reveals the validity of the data-driven wavefront attributes. Combining the simultaneous search with conflicting dip processing for the 3D CRS stack further improved reflected energy and diffraction details when compared with results without simultaneous search and/or conflicting dip processing.

Global optimization strategies for implementing 3D common-reflection-surface stack using the very fast simulated annealing algorithm: Application to real land data

The 3D common-reflection-surface (CRS) stack operator depends on eight kinematic wavefield attributes that must be extracted from the prestack data. These attributes are obtained by an efficient optimization strategy based on the maximization of the coherence measure of the seismic reflection events included by the CRS stacking operator. The main application of these kinematic attributes is to simulate zero-offset stacked data; however, they can also be used for regularization of the prestack data, prestack migration, and velocity model determination. The initial implementations of the 3D CRS stack used grid-search techniques to determine the attributes in several steps with the drawback that accumulated errors can deteriorate the final result. In this work, the global optimization very fast simulated annealing algorithm is used to search for the kinematic attributes by applying three optimization strategies for implementing CRS stacking: (1) simultaneous global search of five kinematic attributes of the 3D common-diffraction-surface stacking operator, (2) two-step global optimization strategy to first search for three attributes and then five attributes of the CRS stacking operator, and (3) simultaneous global search of eight kinematic attributes of the CRS operator. The proposed CRS stacking algorithms are applied to land data of the Potiguar Basin, Brazil. It is demonstrated that the one-step optimization strategy of the eight parameters produces the best results, however, with a higher computational cost.

A comparative study of common-reflection-surface prestack time migration and data regularization: Application in crooked-line data

To improve the time-domain imaging of poor-quality seismic data, the common-reflection-surface (CRS) stack method was introduced to simulate zero-offset (ZO) stacked sections from a multicoverage data set based on automatic coherence analysis of seismic signals. This method produces improved ZO stacked sections with a high signal-to-noise ratio (S/N) and good continuity of reflection events. However, the stacking results may have some undesirable artifacts that can degrade the poststack migrated image. To overcome these drawbacks, I have developed a prestack data regularization method, based on CRS partial stacks, which produces prestack data with high S/N and enhanced reflection events. The regularized data are usually applied for velocity analysis and conventional prestack migration in the time and depth domains. Recently, the CRS stacking operator has also been applied for developing a new type of prestack beam migration. This new migration combines the classic Kirchhoff migration with the CRS stack method, in which the beam-forming process stacks locally coherent events that are performed using the CRS operator during migration. This work reviews this CRS-based prestack migration method in the time domain and presents a comparative study with the main standard applications of the CRS stack method, such as CRS stacking plus poststack time migration and CRS-based regularization plus prestack time migration (PSTM). To evaluate its effectiveness and reliability, CRS-based PSTM and CRS-based prestack data regularization were applied in a crooked line. The time-migrated image resulting from the regularized data has strong migration artifacts due to the crookedness of the seismic line; in contrast, the CRS-based time migration provides a good-quality image without migration artifacts.

Common Reflection Surface Stack Imaging of the Proterozoic Chambal Valley Vindhyan Basin and Its Boundary Fault in the Northwest India: Constraints on Crustal Evolution and Basin Formation

AbstractThe Vindhyan basin of northwestern and central India is one of the largest undeformed Meso‐Neoproterozoic basins in the world with likely potential of hydrocarbons. Crustal seismic reflection data along a 165‐km long Chandli‐Bundi‐Kota‐Kunjer profile of the Chambal Valley Vindhyan basin processed using common reflection surface stack method brought out new crustal features, which were missing in earlier images. A gently dipping structure of the basin is imaged with a maximum of 7.5‐km thick Proterozoic sediments, 1.5‐km thick volcanic sequence, and the granitic basement at 9.0‐km depth. The Great Boundary Thrust, a NW dipping crustal‐scale regional tectonic feature outcropping at Bundi, and a new NW dipping reflection band from 9‐ to 30‐km depth, named here as the Chambal thrust, are imaged beneath Bundi‐Kota segment. Subduction and collision are responsible for evolution of these thrusts implying horizontal crustal growth. Seismic images of compression on one side and extension on another side along with differences in the Moho characteristics and other constraints from geophysical data around Kota indicate the presence of a new tectonic boundary with a strong lateral discontinuity and strike‐slip features. The Moho topography is delineated for the first time revealing a crustal thickness ranging from 40 to 44 km. A 9‐ to 12‐km thick mafic underplating at the lower crust suggests an important postcollisional process indicating vertical crustal growth. Based on the images from the present reflection study, a geodynamic model of the region is suggested in a plate tectonic framework, which may apply to similar Paleoproterozoic collisional areas and associated basin formation.

The use of Graphic User Interface for development of a user-friendly CRS-Stack software

The development of a user-friendly Common Reflection Surface (CRS) Stack software that has been built by implementing Graphical User Interface (GUI) is described in this paper. The original CRS-Stack software developed by WIT Consortium is compiled in the unix/linux environment, which is not a user-friendly software, so that a user must write the commands and parameters manually in a script file. Due to this limitation, the CRS-Stack become a non popular method, although applying this method is actually a promising way in order to obtain better seismic sections, which have better reflector continuity and S/N ratio. After obtaining successful results that have been tested by using several seismic data belong to oil companies in Indonesia, it comes to an idea to develop a user-friendly software in our own laboratory. Graphical User Interface (GUI) is a type of user interface that allows people to interact with computer programs in a better way. Rather than typing commands and module parameters, GUI allows the users to use computer programs in much simple and easy. Thus, GUI can transform the text-based interface into graphical icons and visual indicators. The use of complicated seismic unix shell script can be avoided. The Java Swing GUI library is used to develop this CRS-Stack GUI. Every shell script that represents each seismic process is invoked from Java environment. Besides developing interactive GUI to perform CRS-Stack processing, this CRS-Stack GUI is design to help geophysicists to manage a project with complex seismic processing procedures. The CRS-Stack GUI software is composed by input directory, operators, and output directory, which are defined as a seismic data processing workflow. The CRS-Stack processing workflow involves four steps; i.e. automatic CMP stack, initial CRS-Stack, optimized CRS-Stack, and CRS-Stack Supergather. Those operations are visualized in an informative flowchart with self explanatory system to guide the user inputting the parameter values for each operation. The knowledge of CRS-Stack processing procedure is still preserved in the software, which is easy and efficient to be learned. The software will still be developed in the future. Any new innovative seismic processing workflow will also be added into this GUI software.

Utilizing diffractions in wavefront tomography

Wavefront tomography is known to be an efficient and stable approach for velocity inversion that does not require accurate starting models and does not interact directly with the prestack data. Instead, the original data are transformed to physically meaningful wavefront attribute fields. These can be automatically estimated using local-coherence analysis by means of the common-reflection-surface (CRS) stack, which has been shown to be a powerful tool for data analysis and enhancement. In addition, the zero-offset wavefront attributes acquired during the CRS stack can be used for sophisticated subsequent processes such as wavefield characterization and separation. Whereas in previous works, wavefront tomography has been applied mainly to reflection data, resulting in smooth velocity models suitable for migration of targets with moderately complex overburden, we have emphasized using the diffracted contributions in the data for velocity inversion. By means of simple synthetic examples, we reveal the potential of diffractions for velocity inversion. On industrial field data, we suggest a joint inversion based on reflected and diffracted contributions of the measured wavefield, which confirms the general finding that diffraction-based wavefront tomography can help to increase the resolution of the velocity models. Concluding our work, we compare the quality of a reverse time migrated result using the estimated velocity model with the result based on the inversion of reflections, which reveals an improved imaging potential for a complex salt geometry.

Seismic image enhancement of mud volcano bearing complex structure by the CDS method, a case study in SE of the Caspian Sea shoreline

Improving seismic image quality in complex geological structures remains a challenge in seismic imaging. In complex media, imaging of geological structures such as the boundary of salt diapirs, faults, folding systems, overthrust zones, and unconformities are controversial and challenging tasks. Therefore, new imaging methods such as full waveform inversion, path-integral seismic imaging, reverse time migration, and the optimized common reflection surface stack methods were introduced to face these challenges. The common reflection surface stack method was used frequently to resolve some of the problems in complex structure seismic imaging. However, besides its great advantage in enhancing the quality of seismic section, it faces a problem with conflicting dips. The common reflection surface stack operator is an approximation of the reflection response of a curved interface in an inhomogeneous medium. In this study, a new strategy in the common reflection surface stack is introduced, which completely resolves the problem of conflicting dips in complex structures. Compared to the common reflection surface stack, the new stacking operator is the approximation of diffraction response of a diffraction point in depth. The kinematic wavefield attributes are defined for that diffraction point, whereas curvature of the interface is not fully considered. In the introduced strategy, there would be a stacking operator for each diffraction ray from the diffractor to the surface. Thus, the new operator gathers more energy that might get lost in imaging due to simplified operator in the other methods. The new method was applied to seismic data from a complex geological mud volcano bearing structure from south east of the Caspian Sea shoreline. This area includes numerous mud volcanoes which act as indicators of gas reservoirs. As a natural phenomenon, mud absorbs the seismic energy and deteriorates the quality of the final seismic section. Therefore, obtaining accurate image of the subsurface structures here, in the boundary portion of the mud volcano, is questionable. To overcome this problem, the new method was used to obtain a stacked section with all the possible diffraction energies. Subsequently, the stacked section underwent post stack depth migration. The final depth image proves the advantage of the new stacking operator for imaging in complex structures. Finally it could be concluded that this method could be used for imaging structures with sharp reflector truncations such as faults, diapirs, and unconformities.

Seismic data enhancement and regularization using finite offset Common Diffraction Surface (CDS) stack

The Common Reflection Surface stack is a robust method for simulating zero-offset and common-offset sections with high accuracy from multi-coverage seismic data. For simulating common-offset sections, the Common-Reflection-Surface stack method uses a hyperbolic traveltime approximation that depends on five kinematic parameters for each selected sample point of the common-offset section to be simulated. The main challenge of this method is to find a computationally efficient data-driven optimization strategy for accurately determining the five kinematic stacking parameters on which each sample of the stacked common-offset section depends. Several authors have applied multi-step strategies to obtain the optimal parameters by combining different pre-stack data configurations. Recently, other authors used one-step data-driven strategies based on a global optimization for estimating simultaneously the five parameters from multi-midpoint and multi-offset gathers. In order to increase the computational efficiency of the global optimization process, we use in this paper a reduced form of the Common-Reflection-Surface traveltime approximation that depends on only four parameters, the so-called Common Diffraction Surface traveltime approximation. By analyzing the convergence of both objective functions and the data enhancement effect after applying the two traveltime approximations to the Marmousi synthetic dataset and a real land dataset, we conclude that the Common-Diffraction-Surface approximation is more efficient within certain aperture limits and preserves at the same time a high image accuracy. The preserved image quality is also observed in a direct comparison after applying both approximations for simulating common-offset sections on noisy pre-stack data.