Depth Domain Research Articles

Recovery of Web Citations using Time Travel in Journal of Informetrics

The present paper explores the accessibility and recovery of web citations using Time Travel in the Journal of Informetrics during the year 2008-2017. A total of 647 articles were downloaded and 24901 references were extracted. Out of 3546 web citations2084 references contained URLs, DOIs were found in 1298 references and 164 references contained arXiv, WOS article identifier, etc. It was found that 3163 web citations were accessible and the remaining 383 web citations were missing. The study also investigated the characteristic features of display and destination URLs like the path depth, URL length, file format, and top-level domain.

Imaging Top of Volcanic Mounds Using Seismic Time- and Depth-Domain Data Processing

A seismic survey identified a basalt flow that could consist of cap rock of CO2 storage beneath saline aquifer sediment in the Southern Continental Shelf of Korea. To determine the precise depth of the basalt flow, specific depth-domain data processing of migration velocity analysis (MVA) was applied to the seismic survey data. The accurate depth measurement of a target structure provides crucial information when storing and stabilizing injected CO2 beneath basalt cap rock. Strong reflections of seismic amplitude at the volcanic mounds were adjusted from the time domain to the exact depth domain by the iterated velocity using MVA. The confidence of the updated velocity was verified by the horizontal alignment of seismic events sorted according to their common reflection point (CRP). The depth difference in volcanic mounds before and after MVA application ranged from 32.5 to 60 m along the vertical axis, showing the eruption shape on the strong-amplitude contour map in detail. The eruption shape of the top of volcanic mounds was verified with spatial continuity in 3D geological interpretation. The presented results provide suitable information that can be used to locate drilling sites and to prepare CO2 injection. The geological model obtained from both time- and depth-domain processing can significantly influence the calculation of the storage volume and can be useful for history matching studies.

Seismic data interpretation for mapping the subsurface structure thickness of top and base parigi formation, Konro field, northern West Java basin

The Northern West Java Basin is one of the basins which has been proven to have oil content. In the exploration stage, we need an effective method in providing a description of seismic cross section model of the subsurface conditions of a study area. This study aims to map the thickness of the subsurface structure of the Parigi formation and understand the interpretation of seismic data in the time and depth domain. Seismic cross section has interpreted to determine the location of the alleged potential for hydrocarbon accumulation. In this study we focus on the top and base Parigi formation and obtain subsurface structure map in the time and depth domain. We use time to depth conversion (velocity interval method) to map the subsurface structure thickness. The results of the study show that there is anomaly built up which has potential as a gathering place for hydrocarbon on Parigi formation. The difference in thickness between the top and base Parigi is indicated by the differences in appearance of the structure map. The depth range shown on this map is around 1850ft-2135ft. So that the thickness of the Parigi formation in the study area is 285ft.

Time correction to eliminate structural ambiguity on velocity anomaly in the upper cibulakan formation of ITEUNG field, northern West Java basin

Converting seismic data or structural maps from time to depth domain is very important in the stage of oil and gas exploration. Interpretation in time domain often produce inaccurate interpretation especially in zones under high velocity such as sub-salt or sub-carbonate. Under this zone, there are pull up velocity anomalies or pseudo-anticline. Otherwise in zones under low velocity such as water bottoms with sharp or fluctuating slopes (canyons), loose material overburden or rapid sedimentation, under detached electric normal faults and shale flaps, there are push down velocity anomaly or pseudo-syncline. The study area is in the Main and Massive Formation of ITEUNG Field, Northern West Java Basin where is proven to have petroleum potential. In the study area there are pull-up velocity anomaly or pseudo-anticline even though in reality they are just flat or even syncline due to the location in the zone under high velocity. This study aims to correct velocity anomaly by doing time correction and convert the time domain structure map into depth domain structure map with the time-depth curve method to eliminate structural ambiguity on velocity anomaly. The result shows that the map is obtained in the form of a depth domain structure map which is more accurate than the time domain structure map. Depth structure map make the interpretation more accurate because the structures in depth structure map is more similar to the original sovereignty after correlating with well data. In this present study shows that pull up velocity anomaly can be avoided so that interpretation can be done more accurately.

Analysis of subsurface structural trend and stratigraphic architecture using 2D seismic data: a case study from Bannu Basin, Pakistan

The present study is focused on the subsurface geology of Bannu Basin, a part of western Indus foreland Pakistan. For this purpose, some regional seismic profiles and deep exploratory wells data have been used in integration.A total of ten mappabale seismic reflection events have been identifed which are representative of specific geological units. In general, based on the seismic the formation trends, the horizons are dipping in the northwest direction of the study area. The area generally deepens toward the northwest due to sediments load toward the northwest. The seismic profile MWI-83 shows a unique faults bounded anticlinal structure that has also been mapped on the two-dimmensional contour maps. This could be regarded as potential hydrocarbon entrapment. The regional seismic profiles are contoured for the entire grid in both time and depth domain to obtain the clearer image of the subsurface individual stratigraphic units. The 2D contour maps for Lower Permian aged Warcha Sandstone, Middle Triassic aged Tredian Formation and Early Jurrasic aged Datta Formation have been prepared using gridded TWT of the seismic profiles. The time and depth contour maps of the Datta Formation and Tredian Formation show a four way clouser oriented in the southeast dierction. The area of the closure was computed which is 24 Sq km approximately. Furthermore, the formation tops of the five wells have been used to correlate the wells for understanding the lateral and vertical variations in the stratigraphic layers. The correlation shows that the Datta Formation’s thickness increases at the centre of the basin whereas decreases on the east and south flanks of the basin. Reasons of Wells failure were concluded on the basis of the final well report and concluded that these well failure occur due to poor quality of the data and also due to some mechanical problems. Reservoircharacterization using statistical rock physics and petrophysics coupled with core data analysis can provide further insights into the hydrocarbon exploration.

Spatiotemporal analysis of seismic velocity changes at Okmok volcano, Alaska and implications from deformation source modeling

In this study, we use ambient noise interferometry to determine temporal changes in seismic velocity at Okmok volcano, Alaska, during the inter-eruptive period between the 1997 and 2008 eruptions. Specifically, we examine seismic velocity changes between 2005 and 2007. We further calculate seismic velocity changes in the frequency and depth domains. Examination of depth-constrained changes in seismic velocity allow us to distinguish between volcanic and non-volcanic processes occurring at Okmok. We show evidence that the presence of overlying lava flows may result in long term increases in the seismic velocity of the subsurface. Using the software package Coulomb 3.3, complementary theoretical volumetric strain modeling of volcanic deformation at Okmok is also carried out. These strain models are interpreted in tandem with our depth-constrained changes in seismic velocity. This joint analysis technique allows us to determine the location of the volcanic deformation at Okmok during the 1997-2008 inter-eruptive period. The location technique that we develop requires the use of only three seismic stations or station pairs in order to locate the center of volcanic deformation. Thus, this technique is a potentially valuable tool for monitoring the location of active magma storage at sparsely instrumented volcanoes worldwide.

Global receiver function observations of the X-discontinuity reveal recycled basalt beneath hotspots

The distribution of chemical heterogeneity beneath hotspots provides important constraints on the source of magmatism and mantle convection. Chemical heterogeneities in the upper mantle produce discontinuities that can be interrogated seismically. One such discontinuity, the X-discontinuity (230-350 km depth), is observed intermittently across the globe, with multiple possible causal mechanisms. However, to better understand the cause of the X-discontinuity and its relationship to mantle upwellings, we require global short wavelength observations, previously unresolved by reflected phases with broad upper mantle Fresnel zones. Discontinuities resulting from seismically observable impedance contrasts can be targeted using high frequency P wave receiver functions (RFs) possessing short wavelength lateral sensitivity (∼100 km) to structures almost directly beneath the station. Thus, below well-instrumented hotspots we can investigate the properties of the X-discontinuity and constrain the causal mechanisms in these locations.Using P-to-s converted teleseismic phases between 30-90∘, we stack RFs in the depth and time-slowness domains at 28 hotspots and 6 cratons globally. This reveals 15 robust X-discontinuity observations beneath hotspots between 244-344 km depth. A further 10 potential observations are present beneath hotspots, and 6 null observations beneath cratons. Two causal mechanisms remain possible at the elevated mantle temperatures expected beneath hotspots. The coesite-stishovite phase transition occurs in eclogite and/or carbonated silicate melt may form under certain conditions. For either mechanism to provide seismically observable impedance contrasts, the upper mantle must be locally enriched in basalt. Assessing the X-discontinuity global distribution reveals a correlation with the Large Low Velocity Provinces, suggesting that mantle plumes may entrain recycled basalt from the lowermost mantle.

Extracting Q Anomalies From Marine Reflection Seismic Data Using Deep Learning

Anelasticity of the earth subsurface medium, which is quantified by the quality factor <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$Q$ </tex-math></inline-formula> , causes the dissipation of seismic energy. Strong attenuation effect resulting from geology such as gas clouds (gas-filled sandstone) is a challenging problem for high-resolution imaging. To compensate the attenuation effect, first we need to accurately estimate the attenuation parameter. However, it is difficult to directly derive a heterogeneous attenuation Q model. This research letter proposes a method to derive a Q model corresponding to strong attenuative media from marine reflection seismic data using convolutional neural network (CNN), a popular deep learning framework. We treat Q anomaly detection problem as a semantic segmentation task and train a network to perform a pixel-by-pixel prediction to invert a pixel group that belongs to the strong level of attenuation probability. The proposed method uses a volume of marine 3-D reflection seismic data for network training and validation, which needs only a small part of real data as the training set due to the feature of U-Net. In the final stage, to evaluate the attenuation model, we validate the predicted heterogeneous Q model using deabsorption prestack depth migration (Q-PSDM), a high-resolution imaging result in depth domain with appropriate compensation is obtained.

From RGB to Depth: Domain Transfer Network for Face Anti-Spoofing

With the rapid development in face recognition, most of the existing systems can perform very well in unconstrained scenarios. However, it is still a very challenging task to detect face spoofing attacks, thus face anti-spoofing has become one of the most important research topics in the community. Though various anti-spoofing models have been proposed, the generalisation capability of these models usually degrades for unseen attacks in the presence of challenging appearance variations, e.g. , background, illumination, diverse spoofing materials and low image quality. To address this issue, we propose to use a Generative Adversarial Network (GAN) that transfers an input face image from the RGB domain to the depth domain. The generated depth clue enables biometric preservation against challenging appearance variations and diverse image qualities. To be more specific, the proposed method has two main stages. The first one is a GAN-based domain transfer module that converts an input image to its corresponding depth map. By design, a live face image should be transferred to a depth map whereas a spoofing face image should be transferred to a plain (black) image. The aim is to improve the discriminative capability of the proposed system. The second stage is a classification model that determines whether an input face image is live or spoofing. Benefit from the use of the GAN-based domain transfer module, the latent variables can effectively represent the depth information, complementarily enhancing the discrimination of the original RGB features. The experimental results obtained on several benchmarking datasets demonstrate the effectiveness of the proposed method, with superior performance over the state-of-the-art methods. The source code of the proposed method is publicly available at https://github.com/coderwangson/DFA .

On The Efficiency of P‐Wave Coda Autocorrelation in Recovering Crustal Structure: Examples From Dense Arrays in the Eastern United States

AbstractDue to a sharp contrast in elastic properties across the basement rocks of sedimentary basins (SBs), strong reverberations are generated during the passage of seismic waves. Traditional receiver function methods become inadequate for imaging crustal structure due to the existence of these strong reverberations. We investigate the feasibility of an autocorrelation technique to extract vertical component receiver functions from teleseismic earthquake data and the efficiency of the method to image the crustal architecture in presence of a SB. The method involves spectral whitening followed by autocorrelation and stacking in the depth domain. We show promising results when using temporary seismic networks in the eastern United States. Using synthetic and field‐data examples, we demonstrate that vertical autocorrelations are more efficient than classical radial receiver functions for interpretation purposes in an SB context. We also perform a joint analysis of the amplitudes on radial and vertical receiver functions for characterizing the thickness of the Mohorovičić discontinuity (Moho). We find that the Moho in the eastern United States is a transitional layer (up to 5‐km thick) instead of a sharp boundary. Further, we point out that it is challenging to unambiguously pick and interpret reflected phases on autocorrelations because of the effects of reverberations, cross‐mode contaminations, and a narrow frequency band limiting the resolution of velocity gradients. We therefore send a message of caution for future interpretations based on this technique.

FischerLab: An Application for Generating Fischer Plots and Dynamic Fischer Plots from Wireline Well-Logs and Stratigraphic Data

Fischer plots are a technique that is used to graph changes in accommodation in cyclic carbonate successions. They typically depict the cumulative departure from the average cycle thickness as a function of the cycle number or stratigraphic depth. Many applications of Fischer plots focus on their construction from exposed cyclic carbonate successions. No published programs allow the direct construction of Fischer plots from digital wireline well-logs or dynamic presentations of Fischer plots. Here, we introduce a program known as FischerLab, which facilitates the generation and analysis of Fischer plots. In addition to accepting interpreted stratigraphic data input, FischerLab facilitates the interpretation of digital wireline logs for the generation of Fischer plots in cycle and depth domains, as well as in a dynamic evolving cycle and relative depth domain from an easy-to-use interface. The dynamic construction facilitates the correlation of specific stratigraphic packages to parts of the accommodation cycle while simultaneously tracking the locus of the mean subsidence vector. We demonstrate the use of FischerLab on data derived from the carbonate succession outcrops of the Al-Athrun Formation, Libya, and the Glen Rose Formation, Central Texas, USA, as well as on wireline well-log data from the Western Great Bahama Bank, the Bahamas.

Adversarial Learning for Depth and Viewpoint Estimation From a Single Image

Estimating a depth map and, at the same time, predicting the 3D pose of an object from a single 2D color image is a very challenging task. Depth estimation is typically performed through stereo vision by following several time-consuming stages, such as epipolar geometry, rectification and matching. Alternatively, when stereo vision is not useful or applicable, depth relations can be inferred from a single image as studied in this paper. More precisely, deep learning is applied in order to solve the problem of estimating a depth map from a single image. Then, that map is used for predicting the 3D pose of the main object depicted in the image. The proposed model consists of two successive neural networks. The first network is based on a Generative Adversarial Neural network (GAN). It estimates a dense depth map from the given color image. A Convolutional Neural Network (CNN) is then used to predict the 3D pose from the generated depth map through regression. The main difficulty to jointly estimate depth maps and 3D poses using deep networks is the lack of training data with both depth and viewpoint annotations. This contribution assumes a cross-domain training procedure with 3D CAD models corresponding to objects appearing in real images in order to render depth images from different viewpoints. These rendered images are then used to guide the GAN network to learn the mapping from the image domain to the depth domain. By exploiting the dataset as a source of training data, the proposed model outperforms state-of-the-art models on the PASCAL 3D+ dataset. The code of the proposed model is publicly available at https://github.com/SaddamAbdulrhman/Depth-and-Viewpoint-Estimation/tree/master.

Petrophysical properties prediction from prestack seismic data using convolutional neural networks

We have built convolutional neural networks (CNNs) to obtain petrophysical properties in the depth domain from prestack seismic data in the time domain. We compare two workflows — end-to-end and cascaded CNNs. An end-to-end CNN, referred to as PetroNet, directly predicts petrophysical properties from prestack seismic data. Cascaded CNNs consist of two CNN architectures. The first network, referred to as ElasticNet, predicts elastic properties from prestack seismic data followed by a second network, referred to as ElasticPetroNet, that predicts petrophysical properties from elastic properties. Cascaded CNNs with more than twice the number of trainable parameters as compared to end-to-end CNN demonstrate similar prediction performance for a synthetic data set. The average correlation coefficient for test data between the true and predicted clay volume (approximately 0.7) is higher than the average correlation coefficient between the true and predicted porosity (approximately 0.6) for both networks. The cascaded workflow depends on the availability of elastic properties and is three times more computationally expensive than the end-to-end workflow for training. Coherence plots between the true and predicted values for both cases show that maximum coherence occurs for values of the inverse wavenumber greater than 15 m, which is approximately equal to 1/4 the source wavelength or λ/4. The network predictions have some coherence with the true values even at a resolution of 10 m, which is half of the variogram range used in simulating the spatial correlation of the petrophysical properties. The Monte Carlo dropout technique is used for approximate quantification of the uncertainty of the network predictions. An application of the end-to-end network for prediction of petrophysical properties is made with the Stybarrow field located in offshore Western Australia. The network makes good predictions of petrophysical properties at the well locations. The network is particularly successful in identifying the reservoir facies of interest with high porosity and low clay volume.

Angle‐domain imaging of relative impedance perturbation

ABSTRACTImpedance is a physical parameter that plays an important role in seismic data processing and interpretation. A relative impedance perturbation (the ratio of the impedance perturbation and the impedance for the background models) imaging method in depth domain based on the reflection wave equation is proposed. Under the small perturbation assumption, primary wave and high‐frequency approximation condition, a linear propagation equation of the primary reflection waves based on the relative impedance perturbation was first derived. On this basis, we further derived the imaging formula of the relative impedance perturbation using a linear inversion theory. Then, the source–receiver bidirectional illumination compensation was used to improve the image quality of the subsurface structures. The image result obtained by this method can be used to estimate the relative impedance perturbation. In the angle domain, the extracted near‐angle‐domain image gather with amplitude compensation can estimate the relative impedance perturbation, and the far‐angle image gather provides the estimation of the relative velocity perturbation (the ratio of the velocity perturbation and the background velocity). Finally, several numerical tests demonstrate the effectiveness of the method.

Multiple joint wavefield inversions: Theory and field data implementations

Accurate velocity models for the near surface and overburden are needed for seismic processing and reliable depth imaging. Seismic with multiphysics data, well logs, and geology information need to be quantitatively integrated to obtain high-resolution velocity models. We detail our development and application of the joint wavefield inversion software platform, which enables flexible algorithmic schemes for the integration of multiparameter data and constraints. Inversion is performed in cascade or simultaneously using a variety of input data to constrain the velocity field reconstruction at multiple scales. Coupling mechanisms based on structure similarity together with rock-physics relations are optimally combined to boost resolution and enhance accuracy of the inverted velocity models. Ill-posed inversion problems are then solved using extensive geologic and rock-physics regularization instead of relying on smoothness constraints alone. We detail workflows and algorithms to guide the application of multiparameter joint inversion for velocity model building whether the input data are seismic traveltimes, electromagnetics (time/frequency domains), gravity, and/or surface waves. Extensive applications of multiparameter joint inversion are presented for a variety of complex geologic scenarios in which various multiparameter coupling strategies are illustrated. Robust velocity modeling and enhanced seismic imaging in time and depth domains are obtained as a result, proving the importance of multiphysics integration for reliable earth model parameter estimation.

A fast multipole boundary element method for the three dimensional linear water wave-structure interaction problem with arbitrary bottom topography

We present a numerical method that allows for the efficient solution of general linear water-wave problems with multiple arbitrarily shaped bodies and seabed geometry when the number of unknowns in the problem N is large. The problem domain is divided into an internal region that is modeled using a simple-source boundary integral equation and an outer domain of uniform water depth. The contribution of this work is in introducing an adpative fast-multipole method to the solution procedure, thereby changing the complexity of the problem from O(N3) (or O(N2) with iterative solvers) to O(N) when N is large. The memory requirements scale linearly with N as well. This methodology is needed when the number of bodies is large, when structures with complex shapes are modeled, or when the bottom topography for a problem varies considerably. We use the procedure developed to study the effects of topography over two case examples of floating bodies: 4 truncated vertical cylinders over a bottom protrusion, for which results indicate how variations in topography cause changes to wave loads on the bodies and a configuration of 16 cylinders (with N ~ 150, 000) and the effects of the variable ocean floor are again considered.

Diffraction waves on large aspect ratio rectangular submerged breakwaters

In this paper, hydrodynamic characteristics of two-dimensional submerged breakwaters in water of finite depth and infinite domain interacting with sinusoidal waves are studied from both analytical and numerical approaches. Added mass and damping coefficients are obtained following the determination of radiation potentials in three degrees of freedom (sway, heave and roll). Diffraction problem is then solved according to the linear wave theory and the resulting forces are derived. To verify the results, a comparison of the solution from the analytical method with those obtained by the boundary element method is made and a good agreement is observed. Additionally, high aspect ratio horizontal and vertical flat submerged breakwaters are proposed and their hydrodynamic characteristics are analysed using the numerical and analytical methods. Results show that the horizontal flat submerged breakwater generates low transmitted waves. However, the vertical flat submerged breakwater transmits almost the entire incident wave energy. A parametric study on the effect of submergence depth and the width of the structure on the maximum diffraction wave amplitude, which is responsible for the transmitted wave energy, is carried out and a better understanding of the variation of diffraction wave amplitudes with respect to dominant parameters and wave frequency is achieved.

A Study of Availability and Recovery of URLs in Library and Information Science Scholarly Journals

The present study examines the availability and recovery of web references cited in scholarly journals selected based on their high impact factor published between 2008 and 2017. A PHP script was used to crawl the Uniform Resource Locators (URL) collected from the references. A total of 5720 articles were downloaded and 237418 references were extracted. A total of 33512 URLs were checked for their availability. Further the lexical features of URLs like file extension, path depth, character length and top-level domain was determined. The research findings indicated that out of 33512 web references, 20218 contained URLs, DOIs were found in 12799 references and 495 references contained arXiv or WOS identifier. It was found that 29760 URLs were accessible and the remaining 3752 URLs were missing. Most errors were due to HTTP 404 error code (Not found error). The study also tried to recover the inaccessible URLs through Time Travel. Almost 60.55% of inaccessible URLs were archived in various web archives. The findings of the study will be helpful to authors, publishers, and editorial staff to ensure that web references will be accessible in future.

Validity of DMIST for monitoring healing of diabetic foot ulcers.

A new diabetic foot evaluation scale was proposed, using the seven domains of depth, maceration, inflammation/infection, size, tissue type of the wound bed, type of wound edge, and tunneling/undermining. This scale was named "DMIST" as an acronym from the initials of the domains. The purpose of this study was to evaluate the validity of DMIST. Secondary analysis was conducted in three investigations performed using the diabetic foot ulcer assessment scale (DFUAS) in Japan and Indonesia. Secondary analysis was assessed using DMIST, PUSH, and DESIGN for 4 weeks based on DFUAS score and photographs of diabetic foot ulcers by researchers. Concurrent validity was determined from the correlation of total DMIST scores with PUSH and DESIGN scores. Construct validity was determined by comparisons between total DMIST score and grade of the Wagner classification. Predictive validity was determined by receiver operating characteristic curve analysis for wound non-healing 4 weeks later. Subjects comprised 35 Japanese patients and 118 Indonesian patients. Correlations of total DMIST score with PUSH and DESIGN scores were 0.831 and 0.822, respectively. Comparison of total DMIST scores with grade of the Wagner classification (Grade I vs. Grade II/III vs. Grade IV/V) was p < 0.001. Based on an area under the curve of 0.872, a DMIST score of 9 was selected as a cut-off, offering sensitivity of 0.855 and specificity of 0.786 for wound non-healing 4 weeks later. Our findings suggest that DMIST offers high validity.

Confirmed detection of Palaeogene and Jurassic orbitally-forced sedimentary cycles in the depth domain using False Discovery Rates and Bayesian probability spectra

It has been common practice to assume that power spectral backgrounds in cyclostratigraphy conform to a first-order autoregressive (AR1) model. Vaughan et al. (2011, Paleoceanography) argued that an unbiased approach to fitting the spectral backgrounds, as well as adjustment of confidence levels for multiple frequency testing, should be mandatory during the search in the depth domain for significant spectral peaks. To address these requirements Smoothed Window Averaging to find spectral backgrounds are combined with False Discovery Rates (FDR) for setting confidence levels and were applied to time series from seven Oligocene and Jurassic formations. Bayesian probability spectra provide an alternative method for detecting regular cyclicity. Pre-whitening the linearly detrended time series prior to calculation of Bayesian probabilities avoids confounding effects due to red noise. In all seven formations there are sub-sections associated with spectral peaks exceeding the 5% FDR, in four formations they even exceed the 0.01% FDR. Elevated Bayesian probability at the same frequencies as these significant power spectral peaks, supports the detection of regular cyclicity. This prevalence of detections conflicts with the assertion of Vaughan et al. (2011) that “almost certainly the vast majority of cycle detections … in the stratigraphy literature are false.” In previous publications spectral peaks exceeding the standard 95% level were considered significant so very high confidence levels were not reported. Nevertheless, the examples re-studied demonstrate that pre-Neogene cyclostratigraphic time series do indeed contain regular cycles most likely linked to orbital-forcing.