Using palaeogeographic reconstructions to understand lithological variability within the Early Cretaceous Gage Sandstone and South Perth Shale in the Vlaming Sub-Basin, offshore southern Perth Basin

2014 ◽  
Vol 54 (2) ◽  
pp. 535
Author(s):  
Megan Lech ◽  
Chris Southby ◽  
David Lescinsky ◽  
Luiqi Wang ◽  
Diane Jorgensen ◽  
...  
Keyword(s):  
Early Cretaceous ◽  
Sedimentary Basins ◽  
Sediment Supply ◽  
Seismic Facies ◽  
Depositional History ◽  
Shale Formations ◽  
Sequence Stratigraphic ◽  
Stratigraphic Analysis ◽  
Well Log Analysis ◽  
Breakup Unconformity

The Early Cretaceous Gage Sandstone and South Perth Shale formations are a prospective reservoir-seal pair in the Vlaming Sub-basin. Plays include post-breakup pinch-outs in the Gage Sandstone with the South Perth Shale forming top seal. The Gage reservoir has porosities of 23–30% and permeabilities of 200–1,800 mD. It was deposited in palaeotopographic lows of the Valanginian breakup unconformity and is the lowstand component of the thick deltaic South Perth (SP) Supersequence. To characterise the reservoir-seal pair, a detailed sequence stratigraphic analysis was conducted by integrating 2D seismic interpretation, well log analysis and new biostratigraphic data. Palaeogeographic reconstructions for the SP Supersequence were derived from mapping higher-order prograding packages and establishing changes in sea level and sediment supply. Higher resolution Gage reservoir reconstructions were based on seismic facies mapping. The Gage reservoir forms part of a sand-rich submarine fan system and ranges from canyon confined inner fan deposits to middle fan deposits on a basin plain. Directions of sediment supply are complex, with major sediment contributions from a northern and southern canyon adjacent to the Badaminna Fault Zone. The characteristics of the SP Supersequence differ markedly between the northern and southern parts of the sub-basin due to variations in palaeotopography and sediment supply. Palaeogeographic reconstructions reveal a series of regressions and transgressions leading to infilling of the palaeo-depression. Palaeogeographic reconstructions for the SP Supersequence portray a complex early post-rift depositional history in the central Vlaming Sub-basin. The developed approach is applicable for detailed studies of other sedimentary basins.

Seismic-Scale Geometries and Sequence-Stratigraphic Architecture of Early Cretaceous Syn-Post Rift Carbonate Systems, Presalt Section, Brazil

2020 ◽  
pp. SP509-2019-78
Author(s):  
M. Minzoni ◽  
A. Cantelli ◽  
J. Thornton ◽  
B. Wignall
Keyword(s):  
Early Cretaceous ◽  
Bottom Topography ◽  
Seismic Facies ◽  
Carbonate Production ◽  
Sequence Stratigraphic ◽  
Stratigraphic Architecture ◽  
Platform Margin ◽  
Lacustrine Carbonate ◽  
Sequence Boundaries ◽  
The Impact

AbstractRegional and detailed seismic stratigraphic analyses of Early Cretaceous (Aptian) presalt carbonate sections from offshore Brazil reveal the complex stratigraphic architecture of late- and post-rift lacustrine carbonate systems. The lateral and vertical distribution of calibrated seismic facies within this framework highlights the evolution through time of the carbonate system and bathymetry of the host lacustrine basin. Despite the simple, largely abiotic and microbial components, lacustrine carbonate accumulations formed complex geometries that closely resemble those observed from marine systems, suggesting that a downward tapering carbonate production profile must have occurred. The complexity of the stratigraphic architecture reflects lateral variations in subsidence patterns combined with the interference of the basement topography, palaeo-wind directions, and basinal filling patterns. Well-imaged clinoforms several hundred meters high attest to both the existence of significant lake-bottom topography, locally in excess of 800 meters, and the occurrence of deep water at time of deposition. Platform margin trajectory and vertical and lateral architecture of clinoform packages through time reveal distinct sequence boundaries that can be correlated in detail only locally, demonstrating the impact of syndepositional tectonics, and possibly recurrent isolation of smaller lakes during lowstands. Depositional models from this study fill a gap in current understanding of lacustrine carbonate systems and offer a template for exploration and appraisal of the presalt play.

Tectonostratigraphic framework and depositional history of the Cretaceous–Danian succession of the Danish Central Graben (North Sea) – new light on a mature area

2017 ◽  
Vol 8 (1) ◽  
pp. 9-46 ◽  
Author(s):  
F. S. P. van Buchem ◽  
F. W. H. Smit ◽  
G. J. A. Buijs ◽  
B. Trudgill ◽  
P.-H. Larsen
Keyword(s):  
North Sea ◽  
Depositional Facies ◽  
Depositional History ◽  
Sequence Stratigraphic ◽  
Stratigraphic Analysis ◽  
The North ◽  
Economic Significance ◽  
History Of ◽  
The North Sea ◽  
Depositional Systems

AbstractAn integrated tectonic and sequence stratigraphic analysis of the Cretaceous and Danian of the Danish Central Graben has led to significant new insights critical for our understanding of the chalk facies as a unique cool-water carbonate system, as well as for the evaluation of its potential remaining economic significance.A major regional unconformity in the middle of the Upper Cretaceous chalk has been dated as being of early Campanian age. It separates two distinctly different basin types: a thermal contraction early post-rift basin (Valanginian–Santonian), which was succeeded by an inversion tectonics-affected basin (Campanian–Danian). The infill patterns for these two basin types are dramatically different as a result of the changing influence of the tectonic, palaeoceanographic and eustatic controlling factors.Several new insights are reported for the Lower Cretaceous: a new depositional model for chalk deposition along the basin margins on shallow shelves, which impacts reservoir quality trends; recognition of a late Aptian long-lasting sea-level lowstand (which hosts lowstand sandstone reservoirs in other parts of the North Sea Basin); and, finally, the observation that Barremian–Aptian sequences can be correlated from the Boreal to the Tethyan domain. In contrast, the Late Cretaceous sedimentation patterns have a strong synsedimentary local tectonic overprint (inversion) that influenced palaeoceanography through the intensification of bottom currents and, as a result, the depositional facies. In this context, four different chalk depositional systems are distinguished in the Chalk Group, with specific palaeogeography, depositional features and sediment composition.The first formalization of the lithostratigraphic subdivision of the Chalk Group in the Danish Central Graben is proposed, as well as an addition to the Cromer Knoll Group.

Application of Seismic Sequence Stratigraphy for Delineating Mishrif Prospects in Western Onshore, Abu Dhabi, UAE

2021 ◽  
Author(s):  
Subrata Chakraborty ◽  
Monica Maria Mihai ◽  
Nacera Maache ◽  
Gabriela Salomia ◽  
Abdulla Al Blooshi ◽  
...  
Keyword(s):  
Abu Dhabi ◽  
Seismic Sequence ◽  
Large Area ◽  
Oil Accumulation ◽  
Sequence Stratigraphic ◽  
Stratigraphic Analysis ◽  
Seismic Sequence Stratigraphy ◽  
Well Data ◽  
Seismic Reflectors ◽  
Sweet Spots

Abstract In Abu Dhabi, the Mishrif Formation is developed in the eastern and western parts conformably above the Shilaif Formation and forms several commercial discoveries. The present study was carried out to understand the development of the Mishrif Formation over a large area in western onshore Abu Dhabi and to identify possible Mishrif sweet spots as future drilling locations. To achieve this objective, seismic mapping of various reflectors below, above, and within the Mishrif Formation was attempted. From drilled wells all the available wireline data and cores were studied. Detailed seismic sequence stratigraphic analysis was carried out to understand the evolution of the Mishrif Formation and places where the good porosity-permeability development and oil accumulation might have happened. The seismic characters of the Mishrif Formation in dry and successful wells were studied and were calibrated with well data. The Mishrif Formation was deposited during Late Cretaceous Cenomanian time. In the study area it has a gross thickness ranging from 532 to 1,269 ft as derived from the drilled wells; the thickness rapidly decreases eastward toward the shelf edge and approaching the Shilaif basin. The Mishrif was divided into three third-order sequences based on core observations from seven wells and log signatures from 25 wells. The bottom-most sequence Mishrif 1.0 was identified is the thickest unit but was also found dry. The next identified sequence Mishrif 2.0 was also dry. The next and the uppermost sequence identified as Mishrif 3.0 shows a thickness from 123 to 328 ft. All the tested oil-bearing intervals lie within this sequence. This sequence was further subdivided into three fourth-order sequences based on log and core signatures; namely, Mishrif 3.1, 3.2, and 3.3. In six selected seismic lines of 181 Line Km (LKM) cutting across the depositional axis, seismic sequence stratigraphic analysis was carried out. In those sections all the visible seismic reflectors were picked using a stratigraphic interpretation software. Reflector groups were made to identify lowstand systems tract, transgressive systems tract, maximum flooding surface, and highstand systems tract by tying with the observations of log and core at the wells and by seismic signature. Wheeler diagrams were generated in all these six sections to understand the lateral disposition of these events and locales of their development. Based on stratigraphic analysis, a zone with likely grainy porous facies development was identified in Mishrif 3.0. Paleotopography at the top of Mishrif was reconstructed to help delineate areas where sea-level fall generated leaching-related sweet spots. Analysis of measured permeability data identified the presence of local permeability baffles affecting the reservoir quality and hydrocarbon accumulation. This study helped to identify several drilling locations based on a generic understanding of the Mishrif Formation. Such stratigraphic techniques can be successfully applied in similar carbonate reservoirs to identify the prospect areas.

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