Interpretation Of Seismic Data Research Articles

Seismic data summarization with content-aware resizing

Seam carving (SC) is a computer vision algorithm that resizes natural images by removing their least informative regions. We adapt SC as a novel application to reduce the size of 2D and 3D seismic data with amplitude preservation. Unlike decimation and conventional resizing, the proposed structure-aware reduction algorithm keeps the data’s most important structures and textures. In practice, the SC method uses a gradient-based energy operator and dynamic optimization to find the optimal reduction of the seismic data. We introduce an energy function that uses Gaussian kernels of variable size to compute the magnitude of the data derivatives and implement a quantitative measure to compare different SC alternatives. The proposed Gaussian-based algorithm yields reduced seismic data sets that preserve the main structures and textures of the original data even in the presence of noise. The reduced data are not downsized versions of the original image or volume. We see the seismic summary as representative new data that can help interpreters and processors in gaining insight and assessing the results of filters and seismic attributes with fewer computational resources. Keeping this in mind, the proposed content-aware method is a valuable tool for assisting users in seismic data analysis and interpretation.

Seismic interpretation pitfalls caused by interference effects, exemplified by seismic modeling of outcropping chalk successions

Interference and inherent resolution limitations are well-recognized problems in reflection seismic data and have over time led to misinterpretations. Acquisition of seismic data containing a broad range of frequencies, including high frequencies, does not solve this problem but merely moves the problem to a finer scale. Forward seismic modeling of known geologic scenarios is a valuable tool for studying anticipated seismic responses of successions with a given set of geologic and/or rock physical characteristics and for predicting interpretational challenges. We perform finite-difference-based seismic forward modeling on a conceptual geologic model derived from outcropping chalk sections in southeast Denmark and evaluate possible pitfalls that may hamper interpretation of seismic data acquired from strata with similar characteristics. We demonstrate that interbedded strata with contrasting physical properties and variable thickness can result in interference effects resembling faults and fractures. The result has significance for characterization, e.g., geothermal sites, potential CO2 storage targets, groundwater reservoirs, and hydrocarbon exploration sites, in which the proper imaging of faults and fractures from seismic data is an essential task.

Attribute analysis as a tool for determining the areas of the late diagenetic Main Dolomite deposits and assessing the stability of the seismic signal parameters

The results of the lithofacial analysis of data from the Moracz 3D seismic survey were among the main premises leading to the positioning of the new petroleum exploration well in that area. Unfortunately, the reservoir properties of the drilled part of the Main Dolomite carbonates differed significantly from those anticipated by the analysis of the amplitudes of the seismic signal recorded. Such surprisingly negative results impelled the reinterpretation of 3D seismic data. Hence, a number of analyses of the amplitudes, the frequencies, and the variability of phase shift were carried out in order to determine the influence of these parameters on the lithofacial interpretation of seismic data. The results revealed a fundamental error of amplitude with the extraction maps. It appeared that the distribution of amplitudes is not essentially controlled by the reservoir properties of the Main Dolomite carbonates but by the fault shadow effect coming from Mesozoic graben in the overburden. In addition, a large diversity of frequency spectra was found, which, combined with the small thickness of the exploration level, could have contributed to incorrect identification of seismic reflections. There was also a change in seismic signatures from the same reflection in different parts of the survey, raising doubts about the distribution of the phase rotation. In order to recognize phase rotation diversity, a new seismic data analysis was based upon the selected Triassic sediments of high impedance. The obtained maps demonstrated significant variability within the data volume due to attenuation. The reinterpreted data from the Moracz 3D seismic survey proved the uneven and unstable distribution of amplitudes, frequencies, and phase which resulted in erroneous conclusions of petroleum exploration. After modeling with the use of different frequency ranges, an analysis of the amplitude extraction of the horizons related to the Main Dolomite was performed. Then the amplitude ratio attribute was selected which eliminated the influence of the regional amplitude and frequency distribution and showed the distribution of dolomite properties more reliably than the amplitude extraction maps.

Simultaneous estimation of local intersecting slopes

The local slope of a seismic event is one of the most important attributes in seismic data processing and interpretation. In simple cases, only one slope value corresponds to a data location; however, in some complex geologic environments, such as unconformities or faults, two or more seismic events may intersect and yield several slopes. Although there are well-established methods for computing slopes in simple cases, there is no satisfactory algorithm in complex situations. We first detail the multimodality of coherence of intersecting events in the slope domain, and then propose a novel multimodal optimization method to capture their local slopes simultaneously. In the method, we use the neighborhood-based crowding differential evolution (NCDE) multimodal optimization algorithm cascaded by the hill-valley niche detection function and the Nelder-Mead simplex local search algorithm. Using this approach, we can obtain all of the local intersecting slopes simultaneously and avoid the need for a fine search when fully adopting the NCDE algorithm. The results of our numerical analysis indicate that the proposed method is robust, efficient, and accurate. Furthermore, the application of the proposed method to the dip-steering median filter for random noise attenuation shows better results than the iterative [Formula: see text] method in the case of complex wavefields.

Microfacies and Reservoir Connectivity of Shore Sandbar, Southern Indus Basin, Pakistan

Shore sand bar reservoirs have attracted much attention as one of the target intervals with the greatest potential for petroleum exploration and development in marine sedimentary basins. Nevertheless, due to lack of effective research methods, it is difficult to analyze the rapid lateral change and heterogeneity in a sand bar reservoir, which has a major impact on the efficient petroleum development that seriously restricts the rolling evaluation and efficient development of sand-bar reservoirs. In this study, based on integrated analysis of cores, thin sections, logging, 3D seismic data, production test and dynamic data, through a combination analysis of drilling and seismic interpretation data—the petromineral composition, microfacies and reservoir connectivity of the shore sand bar in the southern Indus basin are investigated, which is used for the fine description of the sandbar reservoir. The results show that the shore sand bar is located in a relatively high-energy shore sedimentary environment, which is conducive to forming a favorable lithologic reservoir. Four sedimentary microfacies types are identified, including center bar, bar edge, inter bar and local mudstone interbeds. The sandbar microfacies are changed rapidly, and different microfacies types overlap each other, especially the inter bar and local mudstone interbeds that overlap and intersect in the center bar and bar edge, which significantly reduces the internal reservoir connectivity as well as intensifying the heterogeneity of the sandbar reservoir. The sandbar reservoir is not connected transversely, the physical properties are changing rapidly, and the sandbar reservoir is cut into several relatively independent oil reservoirs.

Seismogeological and structural characteristic of the Riphean sediments within Aldan-Maya petroleum region

The key features of the geological structure of the Riphean sedimentary cover within the Aldan-Maya petroleum region are considered. Using seismic and acoustic logging data, the velocity characteristics of the Riphean deposits were studied. It was shown that the main acoustic contrasts are associated with the formation of sustained intra-Riphean reflectors. They correlate with the boundaries of formations and series. Based on the results of generalization and interpretation of seismic data on 9 projects of regional prospecting, seismogeological sections and structural maps were constructed, which served as the basis for structural-tectonic zoning of the territory within the Aldan-Maya petroleum region. Tectonic maps are presented for two structural stages - Upper Karelian-Lower Riphean and Upper-Middle Riphean, their fundamental difference is shown, in particular, the large May inclined swell is developed only in the reliefs of the lower Riphean not in the Middle-Upper Riphean surfaces.

Transition to the use of digital assistants in the kinematic interpretation of the data of seismic exploration by the example of the problem of improving the quality of seismic data after summation and reliability of the tectonic model forecast

Modern seismic exploration still faces the challenges of automating processes and increasing the reliability of work results, especially in regions with complex geological conditions. An important place in the cycle of seismic surveys is occupied by the stage of kinematic interpretation, the main purpose of which is a detailed understanding of the structural features of the geological section and obtaining a reasonable geological model of a particular region of study.
 The cost of an error at this stage of the work is quite high, but the interpretation processes require significant labor costs, and the results often contain errors. Standard algorithms and methodological approaches do not fully provide solutions to the full range of tasks, which necessitates the search for new approaches to the interpretation of seismic data.
 In recent years, there has been increasing interest in attracting the capabilities of artificial intelligence to solve production problems. New approaches to solving the problems of the stage of kinematic interpretation of seismic data based on the use of artificial intelligence through machine learning and deep neural networks are proposed:
 technology of elimination of irregular noises of the total seismic data to improve the quality of the initial seismic material and simplify the stage of structural interpretation;
 technology of probabilistic forecast of disturbance systems and obtaining a detailed tectonic model.
 Theoretical foundations are presented and the results of applying technologies on a series of real production projects are demonstrated, which confirm the advantages of using neural networks in interpretation to eliminate subjectivity and significantly reduce time costs at the stage of structural constructions in various geological conditions.

Structural reconstructions effect on oil and gas formation of the Yenisei-Khatanga trough eastern part

The article presents the results of research on the influence of structural reconstructions on the hydrocarbon systems evaluation in the eastern part of the Yenisei-Khatanga trough. Based on seismic data interpretation and paleoprofiles construction, several stages of structural reconstructions in the geological evolution of the basin are established: at the Middle and Late Triassic boundary, Late Triassic and Jurassic boundary, in the Bathonian-Callovian time, Tithonian-Valanginian time, in the Barremian-Aptian time, in the Aptian-Albian time, in the Cenomanian time, and powerful reconstructions in the Cenozoic era. Based on interpretation of geochemical information of the well-core and outcrops, the characterization of the type of organic matter, the amount of initial organic carbon, the oil and gas source potential for the Late Triassic, Lower Jurassic, Middle Jurassic, Upper Jurassic, Lower Cretaceous oil and gas source rocks is given. The results of exploration of the geological structure of the region, the geochemical features of oil and gas source rocks became the basis for building a 2D basin model, which made it possible not only to identify generation kitchen, migration routes and accumulation zones of hydrocarbon fluids, but also to estimate the start time of generation and emigration of hydrocarbons, as well as the moments of interruption of these processes during periods of uplifting of the territory. Changes of the structural plan transformed the configuration of the basin, which led, on the one hand, to the formation of areas where rich in organic matter interlayers accumulated, and, on the other hand, to the interruption of hydrocarbon systems evaluation, reconfiguration and even destruction of deposits.

Комплексные геофизические исследования Западно-Тиманского разлома

In this paper we discuss results of complex geophysical works within the southern and middle segments of the West Timan fault. In the study area, based on the nature of potential fields (magnetic, gravitational), various areas of the West Timan fault were identified: the southern part (Beloborsk block), the central part (Nivshera block), and the northern part (Sindor block). These areas were studied by profile magnetometry on foot and express radon survey. The detailed magnetic survey revealed that the West Timan fault was clearly visible in the gradient sections of the magnetic field, with some degree of conventionality it can be identified within the regional maximum, and it is impossible to trace it in the zone of the regional minimum. Based on the interpretation of seismic data, the location of the West Timan fault has been clarified. The nature of the seismic record does not always allow identifying the exact location of the fold planes, only the difference in the record in individual blocks is clearly noted. The border area sometimes captures 5 km. The express emanation survey showed that the West Timan thrust, in general, was characterized by increased values of radon volumetric activity, where they are further traced to the territory of Timan, while areas of different intensity are distinguished.

Application of passive seismic interferometry for mapping mining waste storage facilities: A case study of Pyhäsalmi mine in Finland

Obtaining knowledge about the structural, geotechnical and hydrogeological conditions of mining waste storage facilities (e.g., tailing storage facilities, TSF) is an important task for mining waste management. From the existing applied geophysics techniques, high-resolution controlled source seismic methods are the most appropriate due to their superior spatial and depth resolution. However, the TSF areas are not often accessible for installation of seismic instruments and application of controlled source. Moreover, TSF areas in active mine sites are characterised by high-level of seismic and acoustic noise, produced by mining operations and other human activities at mine sites. In this study, we show that these problems can be addressed by utilizing passive seismic interferometry, in which cross-correlation of ambient seismic noise is used to obtain the Empirical Green's function (EGF's) of the studied medium. We used this method to evaluate seismic velocities in the TSF and in the near-surface bedrock at the site of the Pyhäsalmi underground mine in Finland. We used the ambient seismic noise recorded in two seismic experiments in the area. In the first experiment, the data were acquired in 2013 along a line 10 km long crossing the area of the underground mine. The second experiment was carried out in the TSF area in 2019. We obtained S-wave velocity models of both bedrock and the TSF by applying multichannel analysis of surface waves (MASW) to surface wave parts of Empirical Green's Functions (EGFs). The analysis of autocorrelation functions of passive seismic data recorded on the TSF surface allowed to us retrieve reflected arrivals from the boundaries inside the TSF. At the same time, we used amplitudes of surface wave parts of EGF's to obtain information about attenuation of surface waves in TSF. Our results show that passive seismic interferometry and interpretation of passive seismic data by different techniques can be a useful tool for inspection of TSF of active mines

Fracture Characterization of Lower Cambrian Niutitang Shale in Cen’gong Block, Southern China

The marine shale of southern China is characterized by old sedimentary formations, multiple tectonic activities, and poor preservation conditions. The fracture system in this shale reservoir is extraordinarily complex, greatly adding to difficulties for shale gas exploration and development. Based on field surveys, drilling cores, seismic data interpretation, and experimental tests, we try to characterize the developmental characteristics of shale fractures at different scales and delineate the stages of fractures in the Cen’gong block. The results show that the Cen’gong block is a saddle-shaped structure formed by the northeast-oriented Banxi anticline and the southwest-oriented Lannigan anticline. There are four types of core fractures developed in the study area, namely, pyrite-filled fractures, fibrous veins, subvertical fractures, and slip fractures, and the forming time of these fractures are later in turn based on the intersecting relationships and analysis of filling minerals. The fracture rose diagram and the paleomagnetic orientation experiments indicate that the fracture direction is mainly NNE and partly NW, consistent with the direction of faults identified in the seismic data. Quantitative statistics have been conducted for fracture aperture, length, and density distribution. The fracture abundance has a close relationship with buried depth and regional faults in the study area.

Visual duplicates search of fracture zones of seismic databasesbased on the method of solving the ICP variational problemin closed form and inverted index

In this paper fast methods are proposed for search the fracture zones in seismic databases on two types of data: seismic section (two-dimensional data) and seismic cube (three-dimensional data). These methods are an integral part of the mapping technology for filtering channels and large volumes of seismic data and useful for automating interpretation of heterogeneous seismic data. The proposed methods for searching the similarity of fracture zones were investigated using the Open Seismic Repository reference dataset, which contains information about geological rocks in the area of the North Sea and compared with other known methods for solving this problem, the results were discussed in the article.

Automated fault detection in the Arabian Basin

In recent years, there has been a rapid development of the computer-aided interpretation of seismic data to reduce the otherwise intensive manual labor. A variety of seed detection algorithms for horizon and fault identification are integrated into popular seismic software packages. Recently, there has been an increasing focus on using neural networks for fully automatic fault detection without manually seeding each fault. These networks are usually trained with synthetic fault data sets. These data sets can be used across multiple seismic data sets; however, they are not as accurate as real seismic data, particularly in structurally complex regions associated with several generations of faults. The approach taken here is to combine the accuracy of manual fault identification in certain parts of the data set with a convolutional neural network that can then sweep through the entire data set to identify faults. We have implemented our method using 3D seismic data acquired from the Arabian Basin in Saudi Arabia covering an area of 1051 km2. The network is trained, validated, and tested with samples that included a seismic cube and fault images that are labeled manually corresponding to the seismic cube. The model successfully identifies faults with an accuracy of 96% and an error rate of 0.12 on the training data set. To achieve a robust model, we further enhance the prediction results using postprocessing by linking discontinued segments of the same fault line, thus reducing the number of detected faults. The postprocessing improves the prediction results from the test data set by 77.5%. In addition, we introduce an efficient framework to correlate the predictions and the ground truth by measuring their average distance value. Furthermore, tests using this approach also have been conducted on the F3 Netherlands survey with complex fault geometries and find promising results. As a result, fault detection and diagnosis are achieved efficiently with structures similar to the trained data set.

Parabolic fitting method for quality factor estimation

The quality factor [Formula: see text] has a wide application range in seismic data processing and interpretation. Compared with the commonly used methods of Q estimation (e.g., the spectral ratio method and the centroid frequency shift method), the logarithmic spectral area difference (LSAD) method exhibits better noise immunity. However, the LSAD method uses the area difference in one frequency band, and the [Formula: see text] values estimated using this method are still unstable under the influence of noise. We have developed a new parabolic fitting (PF) method to estimate Q. This method is an extension of the LSAD method. We derive an analytical relationship between [Formula: see text] and area difference curve of the logarithmic amplitude spectra. Using the logarithmic area difference of multiple frequency bands to fit the parabola, we improve the accuracy and stability of [Formula: see text] estimation. In addition, the PF method does not require special assumptions regarding the source wavelet. We test the PF method in the presence of noise and at varying bandwidths and compare the results with those obtained using the LSAD method. The results of the theoretical examples indicate that the PF method is noise resistant and stable. Applying the PF method to real zero-offset vertical seismic profiling records also indicates that the proposed method can reasonably and stably estimate the [Formula: see text] value of the formation.

Возможности количественной интерпретации результатов спектральной декомпозиции сейсмических данных МОГТ-3D

This paper analyzes the possibility of using the spectral decomposition results for the quantitative prediction of thin layer thickness. The forward wedge-modelling results are considered in order to determine the influence of the thickness of a thin layer on the amplitude response in a band-limited frequency range. A field case of the application of the proposed technique of quantitative spectral decomposition interpretation of the 3D common depth point seismic data is presented.

System design and laboratory tests of an autonomous seismic station for space applications

We introduce a reference concept for a small and lightweight instrument carrier system for operation in isolated areas on Earth (or even on other celestial bodies) that autonomously records data after deployment at a site remote from the main station, thus called Remote Unit (RU). In particular, we present here concepts for realizing an autonomously operating seismometer, including support functions provided by encapsulating the actual instrument into the RU carrier. The conceptualization of the RU is based on the design of MASCOT, and intended for evolving into an instrument carrier for lunar exploration. Still in this paper we focus on the functionality needed for realizing the remote and autonomous aspects of the concept. Evolutionary steps needed for the system design to survive on a planetary body are briefly discussed, but not intensively covered in this paper, but elsewhere.We developed two prototypes of this RU including three seismic sensors each, either fixed, the other one with a built-in self-leveling mechanism. We used standard seismic sensors, which were integrated into a lightweight instrument carrier equipped with all required support structures for remote terrestrial operation, including power, thermal control, and data acquisition (total mass of prototypes not exceeding 3 ​kg and 10 ​kg, respectively). We have carried out laboratory tests and evaluated seismic data from these two types of RU to evaluate noise levels, spectral response, and overall performance of the systems. We demonstrate that the systems provide reproducible data at high signal levels, which warrant comfortable scientific interpretation of seismic data from active and passive experiments. Noise level and detected spectral anomalies (due to mechanical structure and associated Eigenfrequencies) are well within expectations.

Characteristics of High Saturation Hydrate Reservoirs in the Low-Angle Subduction Area of the Makran Accretionary Prism

To delineate the spatial distribution of high saturation gas hydrate reservoirs in the low-angle subduction areas of the Makran Accretionary Prism, we conducted seismic data interpretation and impedance inversion of gas hydrates in the Makran Accretionary Prism and comprehensively analyzed the characteristics of the high saturation gas hydrate reservoirs in the Nankai Trough in Japan and the Shenhu Area in the South China Sea. The results show that the Makran Accretionary Prism features thick sediments, developed transport systems of “two-way gas supply” (i.e., thrust fault and normal fault, thrust fault and high permeable strata), and clear and continuous bottom simulating reflector (BSR). Meanwhile, strong-amplitude reflectors and strong-impedance anomalies coexist in the anticline wing above the BSR. Combined with the proven characteristics of high saturation gas hydrate reservoir, the high saturation gas hydrate reservoirs in the Makran Accretionary Prism are probably mainly distributed in the anticline wings immediately above the BSR. These results provide useful information for the exploration and development of gas hydrate in the low-angle subduction area of the Makran Accretionary Prism.

Fault Recognition Method Based on Attention Mechanism and the 3D-UNet.

Oil and gas reservoirs are of great significance for economic benefits. Faults act as important conduits for transporting hydrocarbons and as essential sealing conditions. The location and morphology of faults reflect changes in the shape of the strata, so fault interpretation of seismic data has been an essential task in oil and gas exploration and development. The traditional fault identification method is time-consuming and inaccurate with large uncertainties. This paper proposed a fault recognition method based on 3D-UNet that added attention mechanisms to a convolutional neural network (CNN). This approach takes advantage of the UNet end-to-end architecture and the attention mechanism to focus on essential areas and suppress irrelevant information, allowing the model to focus on more valuable features. A fault identification network for seismic data was proposed by combining the 3D-UNet architecture with the Squeeze-and-Excitation (SE) attention mechanism. The 3D-UNet architecture comprises two parts: encoding and decoding, and the network architecture realizes end-to-end training. At the same time, SE was used to focus on the advantages of feature channels, further improving the accuracy of the network. The model performance was evaluated using the synthetic dataset provided by Wu. Experimental results show that the proposed model has better prediction performance in terms of accuracy, better recognition continuity, and richer fault detail.

Karmaşık jeolojik ortamlarda gelişen hidrokarbon kapan türlerinin patlayan yansıtıcı yöntemi ile modellenmesi

Structural and stratigraphic hydrocarbon (oil, gas) traps that develop in complex geological environments are formed in regions subjected to tectonically deformation or where there are impermeable rocks in the lateral direction and accumulate significant amounts of hydrocarbons. Reflections from the subsurface media including such traps indicate highly complex behaviour. Therefore, understanding seismic wave propagation in such environments provide important contributions to the interpretation stage. In this study, the modeling of structural and stratigraphic hydrocarbon traps was carried out with exploding reflector (ER) technique. The most important advantages of the method is that the seismic source is located at the reflective interfaces and recorded by the receivers at the surface with the one way travel time. Therefore, as a result of the calculation, directly zero offset sections could be obtained. Numerical calculation of the seismic waves propagated from the source was made by the finite difference method (FDM) which is very useful due to the ability to choose arbitrary input models with different features and provide direct solutions to wave propagation problems. Thus, seismic models of channel, anticline, syncline, normal fault type traps which are frequently encountered in hydrocarbon explorations were calculated easily and quickly by means of the solution of the full wave field with FDM based on the exploding reflector technique. As a result, it has been shown that obtaining zero offset sections (stacked sections) with the ER technique will practically make important contributions to the interpreter during the interpretation of real seismic data.

Two dimensional dynamically focused beam migration in weakly anisotropic media

Anisotropy exists widely in the earth medium. For anisotropic medium, the traditional isotropic migration will lead to the inaccurate images and unfocused energy. Especially for a deep target exploration, ignoring anisotropy will further affect the subsequent seismic data interpretation. As an improved ray method, Gaussian beam migration overcomes the imaging problems of caustics and shadow zones in Kirchhoff migration, and avoids the time-consuming problems of wave equation migrations. However, the imaging quality of the Gaussian beam migration is controlled by the initial beam width at the surface. In this paper, we extend Nowack (2011)’s algorithm to anisotropic media and present an anisotropic dynamically focused beam migration by modifying the propagator of the Gaussian beams. We use anisotropic kinematic and dynamic ray tracing with optimized coefficients to obtain travel times, trajectories and dynamic information. We then use dynamically focused beams for weakly anisotropic media to calculate the Green's function and the Claerbout imaging condition to obtain images. This strategy enables us to improve the imaging quality in the middle and deep layers without reducing the imaging quality in the shallow layers, which will help to overcome the limitation of the initial beam width in Gaussian beam migration. The results for a VTI fault model and the Shengli complex structure model show the accuracy and validity of the proposed method in this paper.