Seismic stratigraphic relationships within a lowstand reservoir system: examples from the Barrow Group, Southern Exmouth Sub-Basin, NW Australia

2014 ◽  
Vol 54 (2) ◽  
pp. 1 ◽  
Author(s):  
Gerry O’Halloran ◽  
Chris Hurren ◽  
Tim O’Hara
Keyword(s):  
Seismic Data ◽  
Late Stage ◽  
Data Sets ◽  
High Quality ◽  
Seismic Control ◽  
Karoo Basin ◽  
Depositional Processes ◽  
Shelf Slope ◽  
Basin Floor ◽  
Surrounding Areas

The Late Jurassic–Early Cretaceous Eskdale and Macedon members of the lower Barrow Group comprise some of the main oil-bearing reservoirs in the Exmouth Sub-basin. These high quality sandstones form the reservoirs in the Stybarrow and Eskdale oil fields. Understanding the architecture of these deepwater successions is important in both exploration and development projects. This paper documents detailed stratigraphic relationships and depositional geometries as defined on high quality seismic data sets and associated well data. An initial phase of lowstand deposition (Eskdale Member) is recorded by the development of two main canyon systems; the Eskdale and slightly younger Laverda canyons. These systems are remarkably well imaged on 3D seismic data, allowing for detailed definition of channel morphology and associated fill and spill facies. Channel complexes are up to 1 km-wide and 100 m-deep, and display evidence for multiple phases of erosion and in-channel aggradation. Overbank/spill facies are also identifiable, including crevasse lateral lobes and ‘chute’ channels. These canyon systems fed contemporaneous downdip basin floor fans that display a variety of classical fan morphologies and depositional elements including terminal lobes, fan pinchout edges, distributary channel systems and localised outflow facies. The distribution and morphology of the Eskdale and Laverda canyons and associated fan intervals can be related to topographic gradient changes within the basin (i.e. from shelf to slope to basin floor). These topographic changes are in turn a response to regional tectonism, in particular active rifting along basin margins. An ensuing phase of less confined, shelf-slope turbidite deposition (Macedon Member) records late-stage lowstand processes. Detailed well and seismic control from the Stybarrow Field and surrounding areas has identified multicyclic sands recording deposition of stacked turbidite lobes. These lobe complexes are more laterally continuous than the canyon facies and are comprised of amalgamated sheet sands and lower-relief channel sands, and are generally between 15–25 m thick. In the greater Stybarrow area the original lobate geometries have been subsequently modified by a phase of late-stage erosion. Outcrop analogues for the Macedon Member can be seen in the lobe complexes from the Tanqua Fan intervals of the Karoo Basin, which are similar in both scale and morphology. These lobe complexes extend laterally for tens of kilometres with constituent individual lobes often displaying evidence for compensational depositional processes. This paper was originally published in the Proceedings of the West Australian Basins Symposium 2013, which was held from 18–21 August 2013 in Perth, Australia.

scholarly journals Fringe or background: Characterizing deep-water mudstones beyond the basin-floor fan sandstone pinchout

2020 ◽  
Vol 90 (12) ◽  
pp. 1678-1705
Author(s):  
Kévin Boulesteix ◽  
Miquel Poyatos-Moré ◽  
David M. Hodgson ◽  
Stephen S. Flint ◽  
Kevin G. Taylor
Keyword(s):  
Deep Water ◽  
Turbidity Currents ◽  
Stratigraphic Correlation ◽  
Low Density ◽  
Karoo Basin ◽  
Depositional Processes ◽  
Stratigraphic Architecture ◽  
Sand Supply ◽  
Stacking Pattern ◽  
Basin Floor

ABSTRACT Mud dominates volumetrically the fraction of sediment delivered and deposited in deep-water environments, and mudstone is a major component of basin-floor successions. However, studies of basin-floor deposits have mainly focused on their proximal sandstone-prone part. A consequent bias therefore remains in the understanding of depositional processes and stratigraphic architecture in mudstone-prone distal settings beyond the sandstone pinchouts of basin-floor fans. This study uses macroscopic and microscopic descriptions of over 500 m of continuous cores from research boreholes from the Permian Skoorsteenberg Formation of the Karoo Basin, South Africa, to document the sedimentology, stratigraphy, and ichnology of a distal mudstone-prone basin-floor succession. Very thin- to thin-bedded mudstones, deposited by low-density turbidity currents, stack to form bedsets bounded by thin packages (< 0.7 m thick) of background mudstones. Genetically related bedsets stack to form bedset packages, which are bounded by thicker (> 0.7 m thick) background mudstones. Stratigraphic correlation between cores suggests that bedsets represent the distal fringes of submarine fan lobe elements and/or lobes, and bedset packages represent the distal fringes of lobe complexes and/or lobe complex sets. The internal stacking pattern of bedsets and bedset packages is highly variable vertically and laterally, which records dominantly autogenic processes (e.g., compensational stacking, avulsion of feeder channels). The background mudstones are characterized by remnant tractional structures and outsize particles, and are interpreted as deposited from low-density turbidity currents and debris flows before intense biogenic reworking. These observations challenge the idea that mud accumulates only from hemipelagic suspension fallout in distal basin-floor environments. Thin background mudstones separating bedsets (< 0.7 m thick) are interpreted to mainly represent autogenically driven lobe abandonment due to up-dip channel avulsion. The thicker background mudstones separating bedset packages (> 0.7 m thick) are interpreted to dominantly mark allogenically driven regional decrease of sand supply to the basin floor. The recognition of sandstone-prone basin-floor fans passing into genetically linked distal fringe mudstones suggests that submarine lobes are at least ∼ 20 km longer than previously estimated. This study provides sedimentological, stratigraphic, and ichnological criteria to differentiate mudstones deposited in different sub-environments in distal deep-water basin-floor settings, with implications for the accurate characterization of basin-floor fan architecture, and their use as archives of paleoenvironmental change.

Imaging improvements from subsalt 3D VSP acquisitions in the Gulf of Mexico

2019 ◽  
Vol 38 (11) ◽  
pp. 865-871 ◽  
Author(s):  
Jean-Paul van Gestel ◽  
Ken Hartman ◽  
Corey Joy ◽  
Qingsong Li ◽  
Michael Pfister ◽  
...  
Keyword(s):  
Gulf Of Mexico ◽  
Seismic Data ◽  
Large Scale ◽  
Survey Design ◽  
Seismic Profile ◽  
Lessons Learned ◽  
Data Sets ◽  
High Quality ◽  
Business Decisions ◽  
Vsp Data

From 2015 through 2018, BP acquired six large-scale 3D vertical seismic profile (VSP) data sets at their Gulf of Mexico assets, two at each of the Thunder Horse, Mad Dog, and Atlantis fields. The acquisition of these large-scale data sets was enabled by the development of a 100-level wireline tool and the adoption of simultaneous shooting. With those two developments, it became feasible to acquire data sets with the coverage and data density needed to build high-quality images of the subsurface using 3D VSP acquisitions. There have been recent advances in finite difference modeling to guide the survey design and the high-quality processing that is required to create the 3D VSP image volumes. These volumes have two main advantages over conventional surface seismic data. First, in 3D VSP acquisition, the receiver can be located below the overlying salt bodies, which allows for illumination of the reservoirs that cannot be achieved using surface seismic data. Second, the location of the receivers closer to the imaging targets enables higher frequency content of the resulting VSP data compared to conventional surface seismic images. Both imaging enhancements can have a significant business value, and the resulting VSP data sets have demonstrated a clear impact on business decisions. In the three case studies, we demonstrate the business impact of the 3D VSP data acquired through improvement of imaging of stratigraphic edges, improved interpretation of fault geometry and orientation, and related improvement of the quality of well planning and targeting. We conclude with discussion on cost, global impact, and present recommendations and lessons learned for future surveys.

Interpretation of depositional facies from seismic data

Geophysics ◽  
1979 ◽  
Vol 44 (2) ◽  
pp. 131-160 ◽  
Author(s):  
J. B. Sangree ◽  
J. M. Widmier
Keyword(s):  
Seismic Data ◽  
Depositional Environments ◽  
Depositional Facies ◽  
Interval Velocity ◽  
Seismic Resolution ◽  
Depositional Processes ◽  
Basin Floor ◽  
Seismic Sections ◽  
Seismic Reflections ◽  
Seismic Lines

Depositional environments can be predicted from seismic data through an orderly approach to the interpretation of seismic reflections. One keystone to this approach is an understanding of the effects of lithology and bed spacing on reflection parameters. Amplitude, frequency, and continuity are some of the parameters most useful for interpreting environments. Reflection amplitude contains information on the velocity and density contrasts at individual interfaces and on the extent of interbedding. Frequency is primarily a characteristic of the nature of the seismic pulse, but it is also related to such geologic factors as the spacing of reflectors or lateral changes in interval velocity. Continuity of reflections is closely associated with continuity of bedding (e.g., continuous reflections suggest widespread, layered deposits). A second keystone to this interpretive approach is the parallelism of reflection cycles to gross bedding and, therefore, to physical surfaces that separate older from younger sediments. Exceptions to this concept include (1) fluid contact reflections, (2) limitations imposed by seismic resolution, and (3) various non‐geologic coherent events. In spite of these exceptions, this concept provides a powerful tool for the analysis of reflection patterns. Reflection cycle patterns include the configuration of reflections (i.e., layered, chaotic, and reflection‐free) and the nature of cycle terminations at the depositional unit boundaries. The external form of the depositional unit can be analyzed from a grid of seismic lines and is valuable in interpreting the depositional processes responsible for the unit. Sheet, sheet drape, wedge, lens, fan, and other forms are described. The areal associations of these forms are often critical to environmental interpretation. Examples of facies interpretation from seismic sections are shown for depositional environments ranging from shelf to basin floor.

Simultaneous deblending and data reconstruction to supply proper time-lapse data sets throughout the field life in a cost-effective and efficient manner

2019 ◽  
Vol 220 (1) ◽  
pp. 568-584
Author(s):  
Shotaro Nakayama ◽  
Gerrit Blacquière
Keyword(s):  
Seismic Data ◽  
Proper Time ◽  
Cost Effective ◽  
Time Lapse ◽  
Data Reconstruction ◽  
Data Sets ◽  
High Quality ◽  
Efficient Manner ◽  
Field Development ◽  
Regulatory Constraints

SUMMARY Acquisition of multiple seismic data sets at different moments in time is capable of satisfying the continuously increasing demand for high-quality subsurface images to reveal both static and dynamic elements during the field development. However, in practice, challenges of pursuing this strategy lie in different perspectives related to budgetary, operational and regulatory constraints. Seismic surveys performed in a compressed manner in time and/or space can provide high-quality seismic data sets in a cost-effective and productive manner. This way of acquisition normally accompanies decompression of recorded data such as deblending and/or data reconstruction. The performance of the recovery process is of fundamental importance in determining the technical success of compressed measurements. Our proposed approach aims at realizing the benefits from compression in data acquisition, contributing to cost and efficiency, while recovering deblended and reconstructed data of sufficient quality. The approach deals jointly with deblending and data reconstruction via a sparse inversion in the frequency–wavenumber domain, coupled with constraints on causality and coherency. Additionally, we formulate a single objective function aimed at sharing static information among vintages and, at the same time, at extracting dynamic changes in the reservoir of interest according to prior subsurface information. We apply the proposed approach to both synthetic and real data. A comparison with a strategy that independently recovers compressed data sets demonstrates the viability of the proposed simultaneous method to effectively enhance the quality of recovered data and extract reliable time-lapse signatures.

scholarly journals Integrated magnetotelluric and seismic investigation of Cenozoic graben structure near Obrzycko, Poland

2021 ◽  
Author(s):  
Adam Cygal ◽  
Michał Stefaniuk ◽  
Anna Kret
Keyword(s):  
Seismic Data ◽  
Geophysical Methods ◽  
Geological Structure ◽  
Data Sets ◽  
Low Velocity ◽  
Shallow Subsurface ◽  
Geophysical Model ◽  
Novel Approach ◽  
Loose Deposits ◽  
Static Corrections

AbstractThis article presents the results of an integrated interpretation of measurements made using Audio-Magnetotellurics and Seismic Reflection geophysical methods. The obtained results were used to build an integrated geophysical model of shallow subsurface cover consisting of Cenozoic deposits, which then formed the basis for a detailed lithological and tectonic interpretation of deeper Mesozoic sediments. Such shallow covers, consisting mainly of glacial Pleistocene deposits, are typical for central and northern Poland. This investigation concentrated on delineating the accurate geometry of Obrzycko Cenozoic graben structure filled with loose deposits, as it was of great importance to the acquisition, processing and interpretation of seismic data that was to reveal the tectonic structure of the Cretaceous and Jurassic sediments which underly the study area. Previously, some problems with estimation of seismic static corrections over similar grabens filled with more recent, low-velocity deposits were encountered. Therefore, a novel approach to estimating the exact thickness of such shallow cover consisting of low-velocity deposits was applied in the presented investigation. The study shows that some alternative geophysical data sets (such as magnetotellurics) can be used to significantly improve the imaging of geological structure in areas where seismic data are very distorted or too noisy to be used alone

scholarly journals Comparing global tomography-derived and gravity-based upper mantle density models

2020 ◽  
Vol 221 (3) ◽  
pp. 1542-1554 ◽  
Author(s):  
B C Root
Keyword(s):  
Seismic Tomography ◽  
Upper Mantle ◽  
Seismic Data ◽  
Gravity Data ◽  
Heterogeneous Data ◽  
Clear Correlation ◽  
Data Sets ◽  
Satellite Gravity ◽  
Similar Density ◽  
Similar Peak

SUMMARY Current seismic tomography models show a complex environment underneath the crust, corroborated by high-precision satellite gravity observations. Both data sets are used to independently explore the density structure of the upper mantle. However, combining these two data sets proves to be challenging. The gravity-data has an inherent insensitivity in the radial direction and seismic tomography has a heterogeneous data acquisition, resulting in smoothed tomography models with de-correlation between different models for the mid-to-small wavelength features. Therefore, this study aims to assess and quantify the effect of regularization on a seismic tomography model by exploiting the high lateral sensitivity of gravity data. Seismic tomography models, SL2013sv, SAVANI, SMEAN2 and S40RTS are compared to a gravity-based density model of the upper mantle. In order to obtain similar density solutions compared to the seismic-derived models, the gravity-based model needs to be smoothed with a Gaussian filter. Different smoothening characteristics are observed for the variety of seismic tomography models, relating to the regularization approach in the inversions. Various S40RTS models with similar seismic data but different regularization settings show that the smoothening effect is stronger with increasing regularization. The type of regularization has a dominant effect on the final tomography solution. To reduce the effect of regularization on the tomography models, an enhancement procedure is proposed. This enhancement should be performed within the spectral domain of the actual resolution of the seismic tomography model. The enhanced seismic tomography models show improved spatial correlation with each other and with the gravity-based model. The variation of the density anomalies have similar peak-to-peak magnitudes and clear correlation to geological structures. The resolvement of the spectral misalignment between tomographic models and gravity-based solutions is the first step in the improvement of multidata inversion studies of the upper mantle and benefit from the advantages in both data sets.

scholarly journals Improved Interpretation of Deep Seismic Reflection Data in Areas of Complex Geology Through Integration With Passive Seismic Data Sets

2018 ◽  
Vol 123 (12) ◽  
pp. 10,810-10,830
Author(s):  
Michael Dentith ◽  
Huaiyu Yuan ◽  
Ruth Elaine Murdie ◽  
Perla Pina-Varas ◽  
Simon P. Johnson ◽  
...  
Keyword(s):  
Seismic Data ◽  
Seismic Reflection ◽  
Data Sets ◽  
Seismic Reflection Data ◽  
Deep Seismic Reflection ◽  
Reflection Data ◽  
Passive Seismic ◽  
Complex Geology

Sparse reflectivity inversion for nonstationary seismic data with surface-related multiples: Numerical and field-data experiments

Geophysics ◽  
2017 ◽  
Vol 82 (3) ◽  
pp. R199-R217 ◽  
Author(s):  
Xintao Chai ◽  
Shangxu Wang ◽  
Genyang Tang
Keyword(s):  
Seismic Data ◽  
Resolution Enhancement ◽  
Synthetic Data ◽  
Data Sets ◽  
Data Set ◽  
Anelastic Attenuation ◽  
Seismic Resolution ◽  
Text Filtering ◽  
The Stability ◽  
Reflectivity Inversion

Seismic data are nonstationary due to subsurface anelastic attenuation and dispersion effects. These effects, also referred to as the earth’s [Formula: see text]-filtering effects, can diminish seismic resolution. We previously developed a method of nonstationary sparse reflectivity inversion (NSRI) for resolution enhancement, which avoids the intrinsic instability associated with inverse [Formula: see text] filtering and generates superior [Formula: see text] compensation results. Applying NSRI to data sets that contain multiples (addressing surface-related multiples only) requires a demultiple preprocessing step because NSRI cannot distinguish primaries from multiples and will treat them as interference convolved with incorrect [Formula: see text] values. However, multiples contain information about subsurface properties. To use information carried by multiples, with the feedback model and NSRI theory, we adapt NSRI to the context of nonstationary seismic data with surface-related multiples. Consequently, not only are the benefits of NSRI (e.g., circumventing the intrinsic instability associated with inverse [Formula: see text] filtering) extended, but also multiples are considered. Our method is limited to be a 1D implementation. Theoretical and numerical analyses verify that given a wavelet, the input [Formula: see text] values primarily affect the inverted reflectivities and exert little effect on the estimated multiples; i.e., multiple estimation need not consider [Formula: see text] filtering effects explicitly. However, there are benefits for NSRI considering multiples. The periodicity and amplitude of the multiples imply the position of the reflectivities and amplitude of the wavelet. Multiples assist in overcoming scaling and shifting ambiguities of conventional problems in which multiples are not considered. Experiments using a 1D algorithm on a synthetic data set, the publicly available Pluto 1.5 data set, and a marine data set support the aforementioned findings and reveal the stability, capabilities, and limitations of the proposed method.

scholarly journals OPEN URBAN AND FOREST DATASETS FROM A HIGH-PERFORMANCE MOBILE MAPPING BACKPACK – A CONTRIBUTION FOR ADVANCING THE CREATION OF DIGITAL CITY TWINS

2021 ◽  
Vol XLIII-B1-2021 ◽  
pp. 125-131
Author(s):  
S. Blaser ◽  
J. Meyer ◽  
S. Nebiker
Keyword(s):  
High Performance ◽  
City Centre ◽  
Data Sets ◽  
High Quality ◽  
Mobile Mapping ◽  
Street Level ◽  
Localization And Mapping ◽  
Digital Twins ◽  
Potential Applications ◽  
The Creation

Abstract. With this contribution, we describe and publish two high-quality street-level datasets, captured with a portable high-performance Mobile Mapping System (MMS). The datasets will be freely available for scientific use. Both datasets, from a city centre and a forest represent area-wide street-level reality captures which can be used e.g. for establishing cloud-based frameworks for infrastructure management as well as for smart city and forestry applications. The quality of these data sets has been thoroughly evaluated and demonstrated. For example, georeferencing accuracies in the centimetre range using these datasets in combination with image-based georeferencing have been achieved. Both high-quality multi sensor system street-level datasets are suitable for evaluating and improving methods for multiple tasks related to high-precision 3D reality capture and the creation of digital twins. Potential applications range from localization and georeferencing, dense image matching and 3D reconstruction to combined methods such as simultaneous localization and mapping and structure-from-motion as well as classification and scene interpretation. Our dataset is available online at: https://www.fhnw.ch/habg/bimage-datasets

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