An Integrated Seismic and Well-Log Sequence Stratigraphic Study Over 32 Grand Isle/West Delta OCS Blocks

Author(s):  
JOHN R. SUTER ◽  
KENNETH C. ABDULAH ◽  
PATTY D. TRAVIS ◽  
PETER A. GLAGOLA ◽  
JAMES W. YOUNG ◽  
...  
1995 ◽  
Vol 35 (1) ◽  
pp. 372 ◽  
Author(s):  
P. A. Arditto

Recent exploration by BHP Petroleum in VIC/ P30 and VIC/P31, within the eastern Otway Basin, has contributed significantly to our understanding of the depositional history of the Paleocene to Eocene siliciclastic Wangerrip Group. The original lithostratigraphic definition of this group was based on outcrop description and subsequently applied to onshore and, more recently, offshore wells significantly basinward of the type sections. This resulted in confusing individual well lithostratigraphies which hampered traditional methods of subsurface correlation.A re-evaluation of the Wangerrip Group stratigraphy is presented based on the integration of outcrop, wireline well log, palynological and reflection seismic data. The Wangerrip Group can be divided into two distinct units based on seismic and well log character. A lower Paleocene succession rests conformably on the underlying Maastrichtian and older Sherbrook Group, and is separated from an overlying Late Paleocene to Eocene succession by a significant regional unconformity. This upper unit displays a highly progradational seismic character and is named here as the Wangerrip Megasequence.Regional seismic and well log correlation diagrams are used to illustrate a subdivision of the Wangerrip Megasequence into eight third-order sequences. This sequence stratigraphic subdivision of the Wangerrip Group is then used to construct a chronostratigraphic chart for the succession within this part of the Otway Basin.


2019 ◽  
Vol 59 (2) ◽  
pp. 920 ◽  
Author(s):  
Duy Nguyen ◽  
Nadege Rollet ◽  
Emmanuelle Grosjean ◽  
Dianne S. Edwards ◽  
Steve Abbott ◽  
...  

The Roebuck Basin and the adjoining Beagle and Barcoo sub-basins are underexplored areas on Australia’s North West Shelf that are undergoing renewed exploration interest since the discovery of oil at Phoenix South 1 in 2014 and subsequent hydrocarbon discoveries in the Bedout Sub-basin. A well folio of 24 offshore wells across the Beagle, Bedout, Rowley and Barcoo sub-basins has been compiled as part of Geoscience Australia’s hydrocarbon prospectivity assessment across the region. It consists of composite well log plots and well correlations that summarise lithology, lithostratigraphy, Geoscience Australia’s newly acquired biostratigraphic and geochemical data as well as results of petrophysical analysis. A revised sequence-stratigraphic interpretation, key petroleum system elements and drilling results are also documented. The wells dominantly target Triassic shoreward facies (Keraudren Formation) as the primary reservoir objective and Jurassic fluvial-deltaic (Depuch Formation) and/or Lower Cretaceous sandy deltaic facies as the secondary objective. The Keraudren Formation sandstones are sealed intra-formationally either by discontinuous units and/or by the regional Cossigny Member. The Jurassic Depuch Formation sandstones are sealed by regional Lower Cretaceous mudstones. Both charge and structure have been identified as critical issues in the Roebuck Basin. In the Beagle Sub-basin, seal integrity and migration pathways are also considered high risk. Well correlations have identified differences in the basin history and provide insights into the distribution of facies and other characteristics of the Jurassic and Triassic successions.


2021 ◽  
Author(s):  
P. Suseno

The Limau Trend Structure is located in the South Sumatera Basin of Indonesia. The main reservoir in this field is the Talang Akar Formation which is deposited in a fluvial complex that changes gradually into a shallow marine depositional environment in a transgressive phase of 3rd order sequence. The sediment deposit was developed from the Late Oligocene to Middle Miocene. A high-resolution sequence stratigraphic interpretation of the 3rd to 4th order was interpreted from the subsurface data (core and well log) combined with the outcrop observation that resulted in a comprehensive input for building a geological model. Based on this framework, the transgressive phase series in each parasequence set produces restricted sediment deposits that have the potential for stratigraphic traps. On the other hand, the amalgamated sands of the regression phase will be related to the structural traps. The RMS amplitude volume from seismic multi attributes analysis shows that the facies is changing with the reservoir distribution. The seismic attributes such as VpVs indicate a hydrocarbon presence. The combination of all data reveals that the stratigraphic traps are the main trapping mechanism in the Limau field. The field development works are now focusing in the northern area, on the transgressive phase of the 4th order parasequence set. It composes of a fluvial complex cycle that has a high potential for a virgin geometrically restricted (lense shaped) reservoir rather than well-connected and sand-rich maximum regressive reservoir facies. This transgressive phase reservoir of parasequence set (4th order) at the Northern Belimbing Field was proven by 2 (two) recently drilled wells. Both wells showed very good hydrocarbon indications and produced oil with an initial rate of 174 bopd & 1265 bopd respectively. These results confirmed the oil prospectivity within the transgressive phase of the 4th order parasequence set at the Northern Limau Trend. The initial resources estimation in the Northern Belimbing Field contains 65 MMBO. This is very promising for the development of the Belimbing Field, Limau Trend.


2015 ◽  
Vol 3 (1) ◽  
pp. SH1-SH9 ◽  
Author(s):  
Bryan W. Turner ◽  
Carlos E. Molinares-Blanco ◽  
Roger M. Slatt

Understanding mudrocks and shale reservoirs has become a significant area of interest within industry and academia in recent years. Of particular interest is understanding the pervasive variability present within these units. This variability became apparent when conventional approaches, such as lithostratigraphic analysis and well log correlation, were coupled with recent developments in palynostratigraphy and chemostratigraphy. A single shallow Woodford Shale research core in the western Arkoma Basin from Pontotoc County, Oklahoma, was used to identify three scales of stratigraphic cyclicity. By comparing the relative abundances of continental sourced pollen and spores to marine-derived acritarchs over a stratigraphic interval, it was possible to extrapolate the overall trends in shoreline trajectory. Conventional well log analysis, such as gamma ray logs, provided a balanced understanding of the interplay between localized changes in sedimentation and regional shifts in the stratigraphic base level, in addition to providing a means to tie these analyses to extensive subsurface data sets. Chemostratigraphic correlations resolved subtle, but stratigraphically significant, shifts in localized patterns in sedimentation. Using these approaches, the Lower and Middle Woodford Shale can be divided into four chemostratigraphic parasequences within a transgressive systems tract defined by well log and core analysis. The Upper Woodford can be separated into an additional four chemostratigraphic parasequences within a highstand systems tract. Chemostratigraphic data also revealed the changing bottom water conditions present at the time of deposition, with a period of localized anoxic conditions recorded in the Lower and Upper Woodford in this part of the basin. These localized changes in sedimentation and environmental conditions can be nested into two longer term regional transgressions and regressions.


1993 ◽  
Vol 33 (1) ◽  
pp. 151
Author(s):  
Peter A. Arditto

Structural traps at the top 'Barrow Group' are the most successful oil exploration targets in the Barrow/Exmouth Sub-basins. However, a reinterpretation of recent exploration activities undertaken by BHP Petroleum Pty Ltd, combined with regional investigations on the Exmouth Plateau, has cast doubt on the validity of accepted stratigraphic nomenclature for the Neocomian succession. A more geologically rational subdivision of the upper part of the Neocomian succession into two discrete sequence stratigraphic units is proposed.Key seismic data from the Exmouth Plateau, tied into wells with good age control, have enabled precise recognition of the Intra-Valanginian Unconformity within the currently-defined Barrow Group. The Barrow Group (sensu stricto) is redefined in this paper as the Barrow Megasequence (restricted to a Berriasian age succession), comprising a rapid progradational phase, which was abruptly terminated by the Intra-Valanginian event.Local erosion of the Barrow Megasequence along the Novara Arch through an Early Valanginian uplift, during the ensuing Valanginian regional transgression, contributed to the development of a parasitic clastic wedge, previously referred to as the Upper Barrow Delta on the Exmouth Plateau and here named the Zeepaard Sequence, with a nominated section in Zeepaard-1. The Zeepaard sequence is terminated by a Top Valanginian unconformity, upon which a final deltaic clastic pulse was deposited as the Birdrong Sequence. Each successive clastic wedge had a more limited development, with the basinward progradation terminating well short of the underlying stratigraphic unit. The Birdrong Sequence was terminated by an Intra-Hauterivian unconformity upon which the highly glauconitic, thin, Mardie Greensand Member of the Muderong Sequence was developed.The Zeepaard Sequence and overlying Birdrong Sequence can be characterised using both seismic and well log character. Well data in particular has enabled detailed stratigraphic mapping of the Birdrong Sequence which is thin and generally not seismically resolvable across the Barrow Sub-basin. This paper presents a detailed sequence stratigraphic analysis of the Birdrong Sequence using well log data.


2012 ◽  
Vol 49 (12) ◽  
pp. 1417-1462 ◽  
Author(s):  
Janice F. Weston ◽  
R. Andrew MacRae ◽  
Piero Ascoli ◽  
M. Kevin E. Cooper ◽  
Robert A. Fensome ◽  
...  

In this study, we build on a foundation of previous biostratigraphic studies for the Scotian Basin, offshore eastern Canada, by conducting new quantitative multidisciplinary biostratigraphic studies of the Mesozoic sections in eight wells: Bonnet P-23, Chebucto K-90, Cohasset L-97, Glenelg J-48, Glooscap C-63, Mohican I-100, South Desbarres O-76, and South Griffin J-13. These wells were chosen to provide good spatial coverage, stratigraphic penetration, and correlation with the seismic grid. We have also evaluated pre-existing biostratigraphic data and undertaken the well-log sequence-stratigraphic interpretation of Upper Triassic to Cenozoic sediments in 16 additional wells using a consistent multidisciplinary event scheme derived from the new wells. Key to the dating of some horizons has been integration of the palynology and micropaleontology (disciplines mostly used previously on the Scotian Margin) with new nannofossil data. Simultaneously we have closely integrated the biostratigraphic results with lithofacies, well-log, and seismic interpretations. Using this integrated approach, we have identified nine regionally mappable sequence-stratigraphic events (unconformities and maximum flooding surfaces, or MFSs): the Intra-Oligocene Unconformity; the Ypresian Unconformity; the Turonian/Cenomanian Unconformity; the Late Albian Unconformity; the Aptian/Barremian Unconformity; the Intra-Hauterivian MFS; the Near-Base Cretaceous Unconformity; the Tithonian MFS; and the Top-Callovian MFS. Additional events of local extent were also recognized in some wells. Our study has led to significant revision of some previous lithostratigraphic picks. The Early Jurassic on the Scotian Margin remains poorly resolved and may be represented by an unconformity on much of the basin periphery.


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