Layer | Fill | Outline |
---|
Map layers
Theme | Visible | Selectable | Appearance | Zoom Range (now: 0) |
---|
Fill | Stroke |
---|---|
Collaborating Authors
Western Australia
ABSTRACT In this article, the Editor of G provides an overview of all technical articles in this issue of the journal.
- Oceania > Australia (0.28)
- North America > Canada (0.28)
- Geophysics > Seismic Surveying > Seismic Processing > Seismic Migration (1.00)
- Geophysics > Seismic Surveying > Seismic Modeling (1.00)
- Geophysics > Seismic Surveying > Seismic Interpretation (1.00)
- Oceania > Australia > Western Australia > North West Shelf > Carnarvon Basin > Exmouth Basin > WA-32-L > Stybarrow Field > Macedon Formation (0.99)
- Oceania > Australia > Western Australia > North West Shelf > Carnarvon Basin > Exmouth Basin > WA-255-P > Stybarrow Field > Macedon Formation (0.99)
The Western Australia Modeling project — Part 2: Seismic validation
Shragge, Jeffrey (Colorado School of Mines) | Lumley, David (University of Texas at Dallas, University of Western Australia) | Bourget, Julien (Total SA) | Potter, Toby (Pelagos Consulting and Education) | Miyoshi, Taka (Research Institute of Innovative Technology for the Earth) | Witten, Ben (Nanometrics Inc.) | Giraud, Jeremie (The University of Western Australia) | Wilson, Thomas (Eliis Paleoscan) | Iqbal, Afzal (The University of Western Australia) | Emami Niri, Mohammad (University of Tehran) | Whitney, Beau (Geoter SAS-Fugro Group)
Abstract 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.
- North America > United States > Illinois > Madison County (0.25)
- Oceania > Australia > Western Australia > North West Shelf (0.24)
- Geology > Geological Subdiscipline > Stratigraphy (1.00)
- Geology > Structural Geology > Tectonics > Plate Tectonics > Earthquake (0.46)
The Western Australia Modeling project — Part 1: Geomodel building
Shragge, Jeffrey (Colorado School of Mines) | Bourget, Julien (Total) | Lumley, David (University of Texas at Dallas, University of Western Australia) | Giraud, Jeremie (The University of Western Australia) | Wilson, Thomas (Eliis) | Iqbal, Afzal (The University of Western Australia) | Emami Niri, Mohammad (University of Tehran) | Whitney, Beau (Geoter SAS-Fugro Group) | Potter, Toby (Pelagos Consulting and Education) | Miyoshi, Taka (Research Institute of Innovative Technology for the Earth) | Witten, Benjamin (Nanometrics)
Abstract 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.
- Research Report > Experimental Study (0.68)
- Research Report > New Finding (0.46)
- Phanerozoic > Mesozoic (1.00)
- Phanerozoic > Cenozoic > Quaternary > Pleistocene (0.69)
- Phanerozoic > Cenozoic > Neogene > Miocene (0.68)
- (2 more...)
- Geology > Sedimentary Geology > Depositional Environment > Transitional Environment (1.00)
- Geology > Sedimentary Geology > Depositional Environment > Marine Environment (1.00)
- Geology > Rock Type > Sedimentary Rock > Clastic Rock > Mudrock (1.00)
- (2 more...)
- Geophysics > Seismic Surveying > Surface Seismic Acquisition (1.00)
- Geophysics > Seismic Surveying > Seismic Processing (1.00)
- Geophysics > Seismic Surveying > Seismic Modeling > Velocity Modeling (1.00)
- Geophysics > Seismic Surveying > Seismic Interpretation (1.00)
- Oceania > Australia > Western Australia > Western Australia > Timor Sea > Browse Basin (0.99)
- Oceania > Australia > Western Australia > North West Shelf > Timor Sea > Browse Basin (0.99)
- Oceania > Australia > Western Australia > North West Shelf > Muderong Shale Formation (0.99)
- (8 more...)
Interpretation-based full waveform inversion of a Western Australian data set
Graham, David (University of Texas at Dallas) | Lumley, David (University of Texas at Dallas) | Zhou, Wei (University of Texas at Dallas) | Shragge, Jeffrey (Colorado School of Mines) | Bourget, Julien (University of Western Australia)
ABSTRACT Full-waveform inversion is an iterative data-fitting procedure used to resolve complex subsurface elastic property models. It has the potential to become a tool for quantitative interpretation at stratigraphic and reservoir scales. To illustrate, we make use of a geologically modeled data set, and conventional marine seismic from the Northern Carnarvon Basin, Western Australia. We utilize a data-driven workflow that mitigates bias and exemplifies interpretational constraints on inversion results. Presentation Date: Tuesday, September 17, 2019 Session Start Time: 8:30 AM Presentation Time: 10:35 AM Location: 221B Presentation Type: Oral
- Oceania > Australia > Western Australia (0.58)
- North America > United States > Illinois > Madison County (0.25)
- Geology > Geological Subdiscipline > Stratigraphy (0.51)
- Geology > Rock Type > Sedimentary Rock (0.47)
ABSTRACT Data regularization by azimuthal moveout (AMO) is an important seismic processing step applied to minimize the deleterious effects of irregular and incomplete acquisition in complex geology. Using isotropic AMO operators on data acquired over azimuthally anisotropic media, though, can lead to poor regularization results due to mixing of wavefield information from neighboring traces with azimuthally varying velocity profiles. An elliptical moveout operator (EMO), representing an extension of isotropic AMO to elliptical azimuthally anisotropic media, is sensitive to variations in the magnitude and the orientation of velocity ellipticity. AMO and EMO operators can be applied to regularize data by moving wavefield information from traces acquired at neighboring offsets and midpoints to infill existing data holes. Unlike AMO, though, EMO operators also can be used in a data conditioning procedure to interpolate energy between seismic traces where input and output velocity profiles are azimuthally elliptical and isotropic, respectively. Resulting processed data volumes are approximately free of elliptical azimuthal anisotropy, as can be shown by comparing analytical traveltimes and numerically calculated wavefield arrivals. EMO thus represents a one-step regularization/conditioning procedure for elliptically azimuthally anisotropic media that is more consistent with wave-equation physics and yields more accurate results than when compared with those from isotropic processing and elliptical residual moveout operator static corrections.
- Geophysics > Seismic Surveying > Seismic Processing > Seismic Migration (0.68)
- Geophysics > Seismic Surveying > Seismic Modeling > Velocity Modeling (0.67)
- Information Technology > Data Science (0.46)
- Information Technology > Software (0.34)
Seismic images of the earth’s interior can be significantly distorted by complex wave propagation effects arising from 3D structural velocity variations, combined with the presence of azimuthal velocity anisotropy within some of the rock layers. Most image-processing techniques attempt to separate and compensate for both of these phenomena sequentially; they rarely address both simultaneously. These approaches implicitly assume that the effects of 3D structural velocity and azimuthal anisotropy are separable, whereas in fact, both effects are coupled together in the seismic data. In the presence of strong azimuthal velocity anisotropy, this can lead to significant errors in seismic velocity estimation and degraded quality of subsurface images, especially for large source-receiver offsets, wide azimuths, and steep geologic dips. Such imaging errors can greatly increase the uncertainty associated with exploring, characterizing, developing and monitoring subsurface geologic features for hydrocarbons, geothermal energy, sequestration, and other important geophysical imaging applications. Our approach simultaneously addressed velocity structure and azimuthal anisotropy by development of an elliptic dip moveout (DMO) operator. We combined the structural-velocity insensitivity of isotropic DMO with elliptic moveout representative of azimuthal velocity anisotropy. Forward and adjoint elliptical DMO operators were then cascaded together to form a single elliptical moveout (EMO) operation, which had a skewed saddle-like impulse response that resembles an isotropic azimuthal moveout operator. The EMO operator can be used as a prestack data conditioner, to estimate azimuthal anisotropy in a domain that is relatively insensitive to 3D velocity structure, or to compensate and map the data back to its original prestack domain in its approximately equivalent isotropic wavefield form. We demonstrated that EMO can reduce structural dip image errors of 10°–20° or more for realistic azimuthal velocity anisotropy values at far offsets.
- Oceania > Australia > Western Australia (0.67)
- North America (0.67)
- Geology > Structural Geology (0.49)
- Geology > Geological Subdiscipline > Stratigraphy (0.35)
- Geophysics > Seismic Surveying > Seismic Processing > Seismic Migration (1.00)
- Geophysics > Seismic Surveying > Seismic Modeling > Velocity Modeling > Seismic Anisotropy (0.46)
- Geophysics > Seismic Surveying > Seismic Interpretation > Seismic Reservoir Characterization > Amplitude vs Offset (AVO) (0.46)
- Oceania > Australia > Western Australia > North West Shelf > Carnarvon Basin > North West Shelf > WA-5-L > Tidepole Field (0.99)
- Oceania > Australia > Western Australia > Great Australian Bight > Bight Basin > Bremer Basin (0.99)
- Oceania > Australia > Western Australia > Carnarvon Basin (0.99)
- (4 more...)
ABSTRACT Seismic reflection data exhibiting the effects of azimuthal velocity variation can be generated by waves propagating through geologic layers containing intrinsic horizontal transverse isotropic (HTI) velocity anisotropy, or through isotropic layers deformed into complex 3D velocity structures, or through both. Most current approaches to processing such data attempt to compensate separately for one physical mechanism or the other, but not both simultaneously. Many azimuthal anisotropy (AA) processing flows initially assume zero structural dip to calculate an azimuthal residual moveout (RMO) correction that flattens CMP gathers after standard isotropic normal moveout. Other approaches initially assume no intrinsic HTI velocity anisotropy in order to generate isotropic migration image gathers, which subsequently are flattened through an azimuthal RMO operator. Both approaches address intrinsic anisotropy and complex 3D structure separately, where in fact both effects may be coupled in the data. This leads to velocity estimation errors and degraded image quality, especially for large offsets, strong velocity anisotropy, and steep geologic dips. The most accurate solution to this problem is to perform iterative full anisotropic prestack depth migration velocity analysis, but this is impractical with current computational resources. For elliptical HTI media and complex 3D structure, we develop a computationally efficient anisotropic elliptical moveout (EMO) operator to precondition and regularize seismic wavefields by incorporating azimuthal velocity profile ellipticity. Forward and adjoint elliptical DMO operators are cascaded together to form a single EMO operation,which has a skewed saddle-like impulse response resembling that of the isotropic azimuthal moveout (AMO) operator, and can correct structural dip image errors commonly 10–20° or more for typical far offset and ellipticity values. EMO can be used to improve imaging results by data regularization to interpolate the azimuthally anisotropic seismic wavefield, and/or by applying data preconditioning to create an approximately equivalent isotropic data set.
- Geology > Structural Geology (0.87)
- Geology > Geological Subdiscipline > Stratigraphy (0.54)
- Geophysics > Seismic Surveying > Seismic Processing > Seismic Migration (1.00)
- Geophysics > Seismic Surveying > Seismic Modeling > Velocity Modeling > Seismic Anisotropy (0.34)