The Western Australia Modeling project — Part 2: Seismic validation

2019 ◽  
Vol 7 (4) ◽  
pp. T793-T807 ◽  
Author(s):  
Jeffrey Shragge ◽  
David Lumley ◽  
Julien Bourget ◽  
Toby Potter ◽  
Taka Miyoshi ◽  
...  
Keyword(s):  
Western Australia ◽  
Seismic Data ◽  
Large Scale ◽  
Seismic Imaging ◽  
Surface Model ◽  
Near Surface ◽  
North West ◽  
Additional Information ◽  
Imaging Results ◽  
Scenario Testing

Large-scale 3D modeling of realistic earth models is being increasingly undertaken in industry and academia. These models have proven useful for various activities such as geologic scenario testing through seismic finite-difference (FD) modeling, investigating new acquisition geometries, and validating novel seismic imaging, inversion, and interpretation methods. We have evaluated the results of the Western Australia (WA) Modeling (WAMo) project, involving the development of a large-scale 3D geomodel representative of geology of the Carnarvon Basin, located offshore of WA’s North West Shelf (NWS). Constrained by a variety of geologic, petrophysical, and field seismic data sets, the viscoelastic WAMo 3D geomodel was used in seismic FD modeling and imaging tests to “validate” model realizations. Calibrating the near-surface model proved to be challenging due to the limited amount of well data available for the top 500 m below the mudline. We addressed this issue by incorporating additional information (e.g., geotechnical data, analog studies) as well as by using soft constraints to match the overall character of nearby NWS seismic data with the modeled shot gathers. This process required undertaking several “linear” iterations to apply near-surface model conditioning, as well as “nonlinear” iterations to update the underlying petrophysical relationships. Overall, the resulting final WAMo 3D geomodel and accompanying modeled shot gathers and imaging results are able to reproduce the complex full-wavefield character of NWS marine seismic data. Thus, the WAMo model is well-calibrated for use in geologic and geophysical scenario testing to address common NWS seismic imaging, inversion, and interpretation challenges.

The Western Australia Modeling project — Part 1: Geomodel building

2019 ◽  
Vol 7 (4) ◽  
pp. T773-T791 ◽  
Author(s):  
Jeffrey Shragge ◽  
Julien Bourget ◽  
David Lumley ◽  
Jeremie Giraud ◽  
Thomas Wilson ◽  
...  
Keyword(s):  
Western Australia ◽  
Seismic Data ◽  
Large Scale ◽  
Viscoelastic Model ◽  
Companion Paper ◽  
3D Seismic ◽  
Seismic Modeling ◽  
North West ◽  
Northern Carnarvon Basin ◽  
And Migration

A key goal in industry and academic seismic research is overcoming long-standing imaging, inversion, and interpretation challenges. One way to address these challenges is to develop a realistic 3D geomodel constrained by local-to-regional geologic, petrophysical, and seismic data. Such a geomodel can serve as a benchmark for numerical experiments that help users to better understand the key factors underlying — and devise novel solutions to — these exploration and development challenges. We have developed a two-part case study on the Western Australia (WA) Modeling (WAMo) project, which discusses the development and validation of a detailed large-scale geomodel of part of the Northern Carnarvon Basin (NCB) located on WA’s North West Shelf. Based on the existing regional geologic, petrophysical, and 3D seismic data, we (1) develop the 3D geomodel’s tectonostratigraphic surfaces, (2) populate the intervening volumes with representative geologic facies, lithologies, and layering as well as complex modular 3D geobodies, and (3) generate petrophysical realizations that are well-matched to borehole observations point-wise and in terms of vertical and lateral trends. The resulting 3D WAMo geomodel is geologically and petrophysically realistic, representative of short- and long-wavefield features commonly observed in the NCB, and leads to an upscaled viscoelastic model well-suited for high-resolution 3D seismic modeling studies. In the companion paper, we study WAMo seismic modeling results that demonstrate the quality of the WAMo geomodel for generating shot gathers and migration images that are highly realistic and directly comparable with those observed in NCB field data.

Full waveform inversion: early start of model building process to resolve the complex near surface model in the Exmouth sub-basin, North West Shelf Australia

2018 ◽  
Vol 58 (2) ◽  
pp. 884
Author(s):  
Lianping Zhang ◽  
Haryo Trihutomo ◽  
Yuelian Gong ◽  
Bee Jik Lim ◽  
Alexander Karvelas
Keyword(s):  
Model Building ◽  
Waveform Inversion ◽  
Velocity Model ◽  
Surface Velocity ◽  
Image Point ◽  
Surface Model ◽  
Full Waveform Inversion ◽  
Near Surface ◽  
North West ◽  
Full Waveform

The Schlumberger Multiclient Exmouth 3D survey was acquired over the Exmouth sub-basin, North West Shelf Australia and covers 12 600 km2. One of the primary objectives of this survey was to produce a wide coverage of high quality imaging with advanced processing technology within an agreed turnaround time. The complexity of the overburden was one of the imaging challenges that impacted the structuration and image quality at the reservoir level. Unlike traditional full-waveform inversion (FWI) workflow, here, FWI was introduced early in the workflow in parallel with acquisition and preprocessing to produce a reliable near surface velocity model from a smooth starting model. FWI derived an accurate and detailed near surface model, which subsequently benefitted the common image point (CIP) tomography model updates through to the deeper intervals. The objective was to complete the FWI model update for the overburden concurrently with the demultiple stages hence reflection time CIP tomography could start with a reasonably good velocity model upon completion of the demultiple process.

Meteorological Impacts of Forest Mortality due to Insect Infestation in Colorado

2012 ◽  
Vol 16 (2) ◽  
pp. 1-11 ◽  
Author(s):  
Christine Wiedinmyer ◽  
Michael Barlage ◽  
Mukul Tewari ◽  
Fei Chen
Keyword(s):  
Land Surface ◽  
Large Scale ◽  
Sensible Heat Flux ◽  
Surface Model ◽  
Multiple Model ◽  
Insect Infestation ◽  
Meteorological Model ◽  
Near Surface ◽  
Forest Mortality ◽  
Forest Dieback

Abstract Physical characteristics of forests and other ecosystems control land–atmosphere exchanges of water and energy and partly dictate local and regional meteorology. Insect infestation and resulting forest dieback can alter these characteristics and, further, modify land–atmosphere exchanges. In the past decade, insect infestation has led to large-scale forest mortality in western North America. This study uses a high-resolution mesoscale meteorological model coupled with a detailed land surface model to investigate the sensitivity of near-surface variables to insect-related forest mortality. The inclusion of this land surface disturbance in the model increased in simulated skin temperature by as much as 2.1 K. The modeled 2-m temperature increased an average of 1 K relative to the default simulations. A latent to sensible heat flux shift with a magnitude of 10%–15% of the available energy in the forested ecosystem was predicted after the inclusion of insect infestation and forest dieback. Although results were consistent across multiple model configurations, the characteristics of forests affected by insect infestations must be better constrained to more accurately predict their impacts. Despite the limited duration of the simulations (one week), these initial results suggest the importance of including large-scale forest mortality due to insect infestation in meteorological models and highlight the need for better observations of the characteristics and exchanges of these disturbed landscapes.

Seismic imaging and velocity analysis for an Alberta Foothills seismic survey

Geophysics ◽  
2001 ◽  
Vol 66 (3) ◽  
pp. 721-732 ◽  
Author(s):  
Lanlan Yan ◽  
Larry R. Lines
Keyword(s):  
Seismic Imaging ◽  
Migration Velocity ◽  
Surface Velocity ◽  
Seismic Survey ◽  
Velocity Analysis ◽  
Prestack Depth Migration ◽  
Near Surface ◽  
Depth Migration ◽  
Migration Velocity Analysis ◽  
Imaging Results

Seismic imaging of complex structures from the western Canadian Foothills can be achieved by applying the closely coupled processes of velocity analysis and depth migration. For the purposes of defining these structures in the Shaw Basing area of western Alberta, we performed a series of tests on both synthetic and real data to find optimum imaging procedures for handling large topographic relief, near‐surface velocity variations, and the complex structural geology of steeply dipping formations. To better understand the seismic processing problems, we constructed a typical foothills geological model that included thrust faults and duplex structures, computed the model responses, and then compared the performance of different migration algorithms, including the explicit finite difference (f-x) and Kirchhoff integral methods. When the correct velocity was used in the migration tests, the f-x method was the most effective in migration from topography. In cases where the velocity model was not assumed known, we determined a macrovelocity model by performing migration/velocity analysis by using smiles and frowns in common image gathers and by using depth‐focusing analysis. In applying depth imaging to the seismic survey from the Shaw Basing area, we found that imaging problems were caused partly by near‐surface velocity problems, which were not anticipated in the modeling study. Several comparisons of different migration approaches for these data indicated that prestack depth migration from topography provided the best imaging results when near‐surface velocity information was incorporated. Through iterative and interpretive migration/velocity analysis, we built a macrovelocity model for the final prestack depth migration.

The Role of Legacy Seismic in Enhancing the Image in the Current Seismic Data – Abu Dhabi: Case Study

2021 ◽  
Author(s):  
Ramy Elasrag ◽  
Thuraya Al Ghafri ◽  
Faaeza Al Katheer ◽  
Yousuf Al-Aufi ◽  
Ivica Mihaljevic ◽  
...  
Keyword(s):  
Seismic Data ◽  
Seismic Survey ◽  
Surface Model ◽  
Noise Attenuation ◽  
Near Surface ◽  
Velocity Models ◽  
Multiple Attenuation ◽  
Seismic Image ◽  
Seismic Acquisition

Abstract Acquiring surface seismic data can be challenging in areas of intense human activities, due to presence of infrastructures (roads, houses, rigs), often leaving large gaps in the fold of coverage that can span over several kilometers. Modern interpolation algorithms can interpolate up to a certain extent, but quality of reconstructed seismic data diminishes as the acquisition gap increases. This is where vintage seismic acquisition can aid processing and imaging, especially if previous acquisition did not face the same surface obstacles. In this paper we will present how the legacy seismic survey has helped to fill in the data gaps of the new acquisition and produced improved seismic image. The new acquisition survey is part of the Mega 3D onshore effort undertaken by ADNOC, characterized by dense shot and receiver spacing with focus on full azimuth and broadband. Due to surface infrastructures, data could not be completely acquired leaving sizable gap in the target area. However, a legacy seismic acquisition undertaken in 2014 had access to such gap zones, as infrastructures were not present at the time. Legacy seismic data has been previously processed and imaged, however simple post-imaging merge would not be adequate as two datasets were processed using different workflows and imaging was done using different velocity models. In order to synchronize the two datasets, we have processed them in parallel. Data matching and merging were done before regularization. It has been regularized to radial geometry using 5D Matching Pursuit with Fourier Interpolation (MPFI). This has provided 12 well sampled azimuth sectors that went through surface consistent processing, multiple attenuation, and residual noise attenuation. Near surface model was built using data-driven image-based static (DIBS) while reflection tomography was used to build the anisotropic velocity model. Imaging was done using Pre-Stack Kirchhoff Depth Migration. Processing legacy survey from the beginning has helped to improve signal to noise ratio which assisted with data merging to not degrade the quality of the end image. Building one near surface model allowed both datasets to match well in time domain. Bringing datasets to the same level was an important condition before matching and merging. Amplitude and phase analysis have shown that both surveys are aligned quite well with minimal difference. Only the portion of the legacy survey that covers the gap was used in the regularization, allowing MPFI to reconstruct missing data. Regularized data went through surface multiple attenuation and further noise attenuation as preconditioning for migration. Final image that is created using both datasets has allowed target to be imaged better.

Multidisciplinary study of the hanging wall of the Kiirunavaara iron ore deposit, northern Sweden

Geophysics ◽  
2012 ◽  
Vol 77 (6) ◽  
pp. B269-B285 ◽  
Author(s):  
Mai-Britt Jensen ◽  
Artem Kashubin ◽  
Christopher Juhlin ◽  
Sten-Åke Elming
Keyword(s):  
Seismic Data ◽  
Hanging Wall ◽  
Low Velocity ◽  
Contact Zones ◽  
Near Surface ◽  
Reflection Seismic ◽  
Imaging Results ◽  
Fracture Development ◽  
Weakness Zones ◽  
The Town

Potential weakness zones due to mining-related fracture development under the town of Kiruna, Sweden, have been investigated by integration of seismic, gravity, and petrophysical data. Reflection seismic data were acquired along two subparallel 2D profiles within the residential area of the town. The profiles of [Formula: see text], each oriented approximately east–west, nearly perpendicular to the general strike of the local geology, crossed several contact zones between quartz-bearing porphyries, a sequence of interchanging sedimentary rocks (siltstone, sandstone, conglomerate, and agglomerate), and metabasalt. The resulting reflection seismic sections revealed a strong east-dipping reflectivity that is imaged down to approximately 1.5 km. The location and orientation of major features agree well between the profiles and with the surface geology and known contact zones between the different rock types. Our imaging results, supported by traveltime modelling, indicate that the contact zones dip 40°–50° to the east. The deepest and the weakest reflections are associated with a [Formula: see text] dipping structure that is presumably related to the Kiirunavaara iron mineralization. Tomographic inversion of refracted arrivals revealed a more detailed image of the velocity distribution in the upper 100–200 m along the profiles, enabling us to identify near-surface low velocity zones. These could be possible weakness zones developed along the lithological contacts and within the geologic units. The structural image obtained from the seismic data was used to constrain data inversion along a 28 km long east–northeast to west–southwest-oriented gravity profile. The resulting density model indicates that the quartz-bearing porphyry in the hanging wall of the Kiirunavaara mineralization can be separated into two blocks oriented parallel to the ore body. One block has an unexpected low density, which could be an indication of extensive fracturing and deformation.

scholarly journals Seismic imaging of reservoir flow properties: Time‐lapse amplitude changes

Geophysics ◽  
2004 ◽  
Vol 69 (6) ◽  
pp. 1425-1442 ◽  
Author(s):  
Don W. Vasco ◽  
Akhil Datta‐Gupta ◽  
Ron Behrens ◽  
Pat Condon ◽  
James Rickett
Keyword(s):  
Seismic Data ◽  
Large Scale ◽  
Seismic Imaging ◽  
Asymptotic Methods ◽  
Time Lapse ◽  
Flow Properties ◽  
Reservoir Permeability ◽  
Amplitude Data ◽  
Reservoir Flow ◽  
Iterative Inversion

Asymptotic methods provide an efficient means by which to infer reservoir flow properties, such as permeability, from time‐lapse seismic data. A trajectory‐based methodology, similar to ray‐based methods for medical and seismic imaging, is the basis for an iterative inversion of time‐lapse amplitude changes. In this approach, a single reservoir simulation is required for each iteration of the algorithm. A comparison between purely numerical and the trajectory‐based sensitivities demonstrates their accuracy. Analysis of a set of synthetic amplitude changes indicates that we are able to recover large‐scale reservoir permeability variations from time‐lapse amplitude data. In an application to actual time‐lapse amplitude changes from the Bay Marchand field in the Gulf of Mexico, we are able to reduce the misfit by 81% in 12 iterations. The time‐lapse observations indicate lower permeabilities are required in the central portion of thereservoir.

Tailored acquisition and processing providing an enhanced subsurface image of the basin architecture, Exmouth Sub-basin, North West Shelf, Australia

2019 ◽  
Vol 59 (2) ◽  
pp. 886
Author(s):  
Alexander Karvelas ◽  
Bee Jik Lim ◽  
Lianping Zhang ◽  
Haryo Trihutomo ◽  
Oliver Schenk ◽  
...  
Keyword(s):  
Oil And Gas ◽  
Model Building ◽  
Waveform Inversion ◽  
Hydrocarbon Exploration ◽  
Surface Velocity ◽  
Seismic Survey ◽  
Image Point ◽  
Surface Model ◽  
Near Surface ◽  
North West

Hydrocarbon exploration has resulted in the discovery of a variety of oil and gas accumulations mainly in Upper Jurassic and Lower Cretaceous intervals. However, the distribution of the different petroleum system elements including Jurassic and Triassic intervals is poorly determined, but required for improved understanding of the complex charge history, as indicated by the variety of hydrocarbon types encountered in the basin. The new WesternGeco multiclient 3D seismic survey extends to the edges of the basin to give a comprehensive picture. Raw hydrophone data were delivered from the vessel as acquisition progressed to begin the near-surface model building. The model building consisted of two major stages: first, using full waveform inversion (FWI) to derive the near-surface velocity field; and, second, common image point (CIP) tomography to update the deeper section beyond the FWI illumination zone. As illustrated herein, various stages of processing and imaging provided a cleaner and crisper dataset across the record length, allowing (1) detailed picking of the events within the entire Mesozoic (Cretaceous–Triassic) section allowing key events to be interpreted and correlated across the area and (2) accurate investigation of the complexity of different aged fault networks and their relationships across the full Exmouth Sub-basin for the first time. In summary, this survey provides a detailed insight into the deeper basin architecture of the Exmouth Sub-basin. The seamless volume imaged to depth allows accurate mapping which is critical to unravel the complex evolutionary history in a basin with proven and significant remaining hydrocarbon potential.

High-resolution Radon preconditioning for full-waveform inversion of land seismic data

2017 ◽  
Vol 5 (4) ◽  
pp. SR23-SR33 ◽  
Author(s):  
Xin Cheng ◽  
Kun Jiao ◽  
Dong Sun ◽  
Zhen Xu ◽  
Denes Vigh ◽  
...  
Keyword(s):  
High Resolution ◽  
Seismic Data ◽  
Waveform Inversion ◽  
Low Frequency ◽  
Velocity Fields ◽  
Surface Velocity ◽  
Surface Model ◽  
Full Waveform Inversion ◽  
Near Surface ◽  
Full Waveform

Over the past decade, acoustic full-waveform inversion (FWI) has become one of the standard methods in the industry to construct high-resolution velocity fields from the seismic data acquired. While most of the successful applications are for marine acquisition data with rich low-frequency diving or postcritical waves at large offsets, the application of acoustic FWI on land data remains a challenging topic. Land acoustic FWI application faces many severe difficulties, such as the presence of strong elastic effects, large near-surface velocity contrast, and heterogeneous, topography variations, etc. In addition, it is well-known that low-frequency transmitted seismic energy is crucial for the success of FWI to overcome sensitivity to starting velocity fields; unfortunately, those are the parts of the data that suffer the most from a low signal-to-noise ratio (S/N) in land acquisition. We have developed an acoustic FWI application on a land data set from North Kuwait, and demonstrated our solutions to mitigate some of the challenges posed by land data. More specifically, we have developed a semblance-based high-resolution Radon (HR-Radon) inversion approach to enhance the S/N of the low-frequency part of the FWI input data and to ultimately improve the convergence of the land FWI workflow. To mitigate the impact of elastic effects, we included only the diving and postcritical early arrivals in the waveform inversion. Our results show that, with the aid of HR-Radon preconditioning and a carefully designed workflow, acoustic FWI has the ability to derive a reliable high-resolution near-surface model that could not be otherwise recovered through traditional tomographic methods.

scholarly journals Sensitivity of the regional European boreal climate to changes in surface properties resulting from structural vegetation perturbations

2015 ◽  
Vol 12 (10) ◽  
pp. 3071-3087 ◽  
Author(s):  
J. H. Rydsaa ◽  
F. Stordal ◽  
L. M. Tallaksen
Keyword(s):  
Land Surface ◽  
Large Scale ◽  
Structural Changes ◽  
Mixed Forest ◽  
Surface Fluxes ◽  
Heat Fluxes ◽  
Energy Partitioning ◽  
The Arctic ◽  
Surface Model ◽  
Near Surface

Abstract. Amplified warming at high latitudes over the past few decades has led to changes in the boreal and Arctic climate system such as structural changes in high-latitude ecosystems and soil moisture properties. These changes trigger land–atmosphere feedbacks through altered energy partitioning in response to changes in albedo and surface water fluxes. Local-scale changes in the Arctic and boreal zones may propagate to affect large-scale climatic features. In this study, MODIS land surface data are used with the Weather Research and Forecasting model (WRF V3.5.1) and Noah land surface model (LSM), in a series of experiments to investigate the sensitivity of the overlying atmosphere to perturbations in the structural vegetation in the northern European boreal ecosystem. Emphasis is placed on surface energy partitioning and near-surface atmospheric variables, and their response to observed and anticipated land cover changes. We find that perturbations simulating northward migration of evergreen needleleaf forest into tundra regions cause an increase in latent rather than sensible heat fluxes during the summer season. Shrub expansion in tundra areas has only small effects on surface fluxes. Perturbations simulating the northward migration of mixed forest across the present southern border of the boreal forest, have largely opposite effects on the summer latent heat flux, i.e., they lead to a decrease and act to moderate the overall mean regional effects of structural vegetation changes on the near-surface atmosphere.

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