FLATTENED TIME SLICES—A STRATIGRAPHIC APPROACH TO 3D SEISMIC INTERPRETATION ON THE NORTH WEST SHELF OF AUSTRALIA

2003 ◽  
Vol 43 (1) ◽  
pp. 255
Author(s):  
K. Martens
Keyword(s):  
Vertical Section ◽  
Depositional Environments ◽  
Time Slice ◽  
North West ◽  
The North ◽  
Exploration Tool ◽  
Depositional Systems ◽  
Complex Channel ◽  
Structural Volume ◽  
Depositional Elements

Conventional time slices are a powerful method of integrating horizon picks and fault picks into a unified interpretation and are a handy way of viewing structures, especially in faulted areas. The limitation is that time slices are seldom useful in viewing the morphology of a horizon. A 3D cube is the present day structural volume; it retains any structure imparted on the geology after deposition. When a time slice is defined, the structural dip limits the area of the integral depositional elements that can be imaged. For example, a depositional surface developed as part of a fluvial-deltaic system is seldom one event and it cannot be easily identified and picked in a vertical section. Flattened time slices take out the regional dip and allow a complete depositional surface to be viewed.The North West Shelf of Australia and especially the Barrow Sub-basin is a particularly suitable place to apply this exploration technique. The entire sedimentary package, laid down in a variety of depositional environments, has been tilted to the northwest by an average of 3°. This strong post-depositional tilt limits the uses of conventional time slices to imaging only the diprelated features of an area. Whereas conventional time slices only make apparent the dip of the section, flattened time slices can reveal subtle and intricate stratigraphic architecture.This paper describes the seismic features of a number of depositional systems from the Barrow Sub-basin and outlines how complex channel systems can be determined by the use of the flattened time slice approach. Given the importance of stratigraphic plays in the Barrow Subbasin, the technique outlined in this paper is considered to be an important exploration tool.

THE DEVELOPMENT AND REGIONAL SIGNIFICANCE OF RIFT-RELATED DEPOSITIONAL SYSTEMS IN THE DAMPIER SUB-BASIN

1996 ◽  
Vol 36 (1) ◽  
pp. 369 ◽  
Author(s):  
L.R. Miller ◽  
S.A. Smith
Keyword(s):  
Time Scale ◽  
Close Association ◽  
Temporal Frequency ◽  
Absolute Error ◽  
Geological Time ◽  
Sediment Distribution ◽  
North West ◽  
The North ◽  
Depositional Systems ◽  
The Relationship

The influence of tectonic control is more apparent than eustatic control on the rift-related stratigraphy of the Dampier Sub-basin. The correlation of observed depositional events to causative processes and global events is problematic due to the use of alternative geological time scales, causing ambiguity and uncertainty. The Harland (1989) time scale with a revised palynological allocation, combined with genetic sequence stratigraphy, and Prosser's concept of the tectonic systems tract, has proved useful during evaluation of the stratigraphy of the Dampier Sub-basin.Palaeo-topography was a major factor in sediment distribution and facies architecture of rift-related strata in the Dampier Sub-basin. This must be considered when assessing the stratigraphic trapping potential for hydrocarbons. There is a close association between the styles of depositional systems observed in the Dampier Sub-basin and stage of rifting and basin development. Five tectonic systems tracts, each with unique depositional systems have been identified and described; pre-rift, rift initiation, rift climax, immediate post-rift and late post-rift tectonic systems tracts.The use of a single time scale has enhanced the relationship between tectonic systems tracts (super-cycles) and the timing of depositional events recorded during previous genetic stratigraphic studies in the North West Shelf. The tectonic nature of super-cycle scale events should be temporally and spatially assessed in detail before the effects of eustatic change are evaluated for rift-related successions of the North West Shelf. The problem can be further exacerbated when the absolute error of chronological dating exceed the temporal frequency of eustacy, causing tenuous correlations of depositional events to a global eustatic curve.

THE STAG OILFIELD

1996 ◽  
Vol 36 (1) ◽  
pp. 130 ◽  
Author(s):  
J. Crowley ◽  
E.S. Collins
Keyword(s):  
Water Saturation ◽  
Vertical Section ◽  
Far East ◽  
Total Porosity ◽  
Analysis Data ◽  
Effective Porosity ◽  
Seismic Survey ◽  
North West ◽  
The North ◽  
Southeastern Margin

The Stag Oilfield is located approximately 65 km northwest of Dampier and 25 km southwest of the Wandoo Oilfield near the southeastern margin of the Dampier Sub-basin, on the North West Shelf of Western Australia,.The Stag-1 discovery well was funded by Apache Energy Ltd (formerly Hadson Energy Ltd), Santos Ltd and Globex Far East in June 1993 under a farmin agreement with BHP Petroleum Pty Ltd, Norcen International Ltd and Phillips Australian Oil Co. The well intersected a gross oil column of 15.5 m within the Lower Cretaceous M. australis Sandstone. The oil column intersected at Stag-1 was thicker than the pre-drill mapped structural closure.A 3D seismic survey was acquired over the Stag area in November 1993 to define the size and extent of the accumulation. Following processing and interpretation of the data, an exploration and appraisal program was undertaken. The appraisal wells confirmed that the oil column exceeds mapped structural closure and that there is a stratigraphic component to the trapping mechanism. Two of the appraisal wells were tested; Stag-2 flowed 1050 BOPD from a 5 m vertical section and Stag-6 flowed at 6300 BOPD on pump from a 1030 m horizontal section.Evaluation of the well data indicates the M. australis Sandstone at the Stag Oilfield is genetically related to the reservoir section at the Wandoo Oilfield. The reservoir consists of bioturbated glauconitic subarkose and is interpreted to represent deposition that occurred on a quiescent broad marine shelf. Quantitative evaluation of the oil-in-place has been hampered by the effects of glauconite on wireline log, routine and special core analysis data. Petrophysical evaluation indicates that core porosities and water saturations derived from capillary pressure measurements more closely match total porosity and total water saturation than effective porosity and effective water saturation.A development plan is currently being prepared and additional appraisal drilling in the field is expected.

Stratigraphy of the Birdrong: an integrated approach

2012 ◽  
Vol 52 (2) ◽  
pp. 684
Author(s):  
Jessica Trainor ◽  
Jeffery Goodall ◽  
Kathryn Amos
Keyword(s):  
Integrated Approach ◽  
Predictive Tool ◽  
Palynological Analysis ◽  
North West ◽  
The North ◽  
Study Interval ◽  
Depositional Systems ◽  
Northern Carnarvon Basin ◽  
Facies Modelling ◽  
Sequence Boundaries

A detailed study of the Early Cretaceous Birdrong Sequence (S. areolata - P. burgeri) has been undertaken in the East Spar and Woollybutt fields, which lie in the northern end of the Barrow Delta complex in the Barrow Sub-basin, Northern Carnarvon Basin. This project integrates palynological, sedimentological and seismic stratigraphic interpretations to progress our understanding of the way in which the Barrow Delta evolved. The results will help develop remaining hydrocarbon prospectivity in the northern Barrow area. Palynological analysis within the Helby, Morgan and Partridge (2004) zonation scheme for the North West Shelf has enabled the identification of several significant biostratigraphic events, which have allowed further subdivision of the existing broad palynological zones. These palynological events represent influxes of specific dinoflagellate cyst taxa that may be tied to key stratal surfaces. These surfaces include transgressive ravinement surfaces, sequence boundaries and flooding surfaces. The palynological and sedimentological data, when combined, indicate a strong facies relationship between specific taxa and interpreted depositional environment. Such taxa include Gagiella, freshwater and brackish algae, and fully marine dinoflagellate cysts including Kaiwaradinium scrutillinum, Systematophora areolata, Phoberocysta neocomica and Cribroperidinium muderongense. The integration of sedimentology and palynology provides a powerful tool in interpreting depositional systems in shallow marine palaeoenvironments. Initial results indicate this may be used as a predictive tool for reservoir correlation and facies modelling. Key stratal surfaces identified through palynological and sedimentological study will be tested against 3D seismic to understand fully the stratigraphy of the study interval.

LITHOSTRATIGRAPHY OF THE LOWER EROMANGA BASIN SEQUENCE IN SOUTH WEST QUEENSLAND

1987 ◽  
Vol 27 (1) ◽  
pp. 196
Author(s):  
B.H. John ◽  
C.S. Almond
Keyword(s):  
High Energy ◽  
Depositional Environments ◽  
Oil Fields ◽  
North West ◽  
The North ◽  
Investigation Area ◽  
South West ◽  
Basin Surface ◽  
Petroleum Wells ◽  
Eromanga Basin

Five fully-cored and wire-line logged stratigraphic bores have been drilled by the Queensland Department of Mines, relatively close to producing oil fields in the Eromanga Basin, south-west Queensland. Correlations between the stratigraphic bores and petroleum wells have established lithologic control in an area where lithostratigraphy is interpreted mainly from wire-line logs. The Eromanga Basin sequence below the Wallumbilla Formation has been investigated, and a uniform lithostratigraphic nomenclature has been applied; in the past, an inconsistent nomenclature system was applied in different petroleum wells.Accumulation of the Eromanga Basin sequence was initiated in the early Jurassic by major epeirogenic downwarping; in the investigation area the pre-Eromanga Basin surface consists mainly of rocks comprising the Thargomindah Shelf and the Cooper Basin. The lower Eromanga Basin sequence in the area onlaps the Thargomindah Shelf and thickens relatively uniformly to the north-west. The sequence comprises mainly Jurassic/Cretaceous terrestrial units in which vertical and lateral distribution is predominantly facies-controlled. These are uniformly overlain by the mainly paralic Cadna-owie Formation, signalling the initiation of a major Cretaceous transgression over the basin.The terrestrial sequence over most of the area comprises alternating coarser and finer-grained sedimentary rocks, reflecting major cyclical changes in the energy of the depositional environment. The Hutton Sandstone, Adori Sandstone and 'Namur Sandstone Member' of the Hooray Sandstone comprise mainly sandstone, and reflect high energy fluvial depositional environments. Lower energy fluvial and lacustrine conditions are reflected by the finer-grained sandstone, siltstone and mudstone of the Birkhead and Westbourne Formations, and 'Murta Member' of the Hooray Sandstone. Similar minor cycles are represented in the 'basal Jurassic' unit. The Algebuckina Sandstone, recognised only in the far south-west of the investigation area, comprises mainly fluvial sandstones.

The Prospectivity and Reservoirs Characteristics of the Triassic Depositional Systems of the North West Shelf, Australia: New Insights

2015 ◽  
Author(s):  
Carl A. Watkins* ◽  
Lisa Buckley ◽  
Peter Baillie ◽  
John Watson ◽  
Andrea Pardon ◽  
...  
Keyword(s):  
North West ◽  
The North ◽  
Depositional Systems

GREENSAND RESERVOIRS IN SILICICLASTIC SHORELINE SYSTEMS: FACIES MODELS FOR HYDROCARBON EXPLORATION

1998 ◽  
Vol 38 (2) ◽  
pp. 132
Author(s):  
I.A. Dyson
Keyword(s):  
Oil And Gas ◽  
Depositional Environments ◽  
Sediment Supply ◽  
Hydrocarbon Exploration ◽  
Correct Identification ◽  
North West ◽  
Sequence Stratigraphic ◽  
The North ◽  
Stratigraphic Framework ◽  
Physical And Chemical

Greensand reservoirs are particularly significant in siliciclastic shoreline systems. Formation of autochthonous glauconite is restricted almost exclusively to the rising limb of the relative sea level (RSL) curve. Depositional environments that are typically developed in response to a rise in RSL are estuaries, barrier bars and shoreface sands. In this setting, the greensands are diachronous and exploration for hydrocarbon reservoirs should ideally be based on a sequence stratigraphic framework. These deposits are characterised by a number of significant surfaces that differ greatly in their origin, geographic extent and chronostratigraphic significance, and their thickness depends on the rate of RSL rise and sediment supply. The identification of significant surfaces bounding or contained within depositional sequences is critical, especially where drillhole samples are either unreliable or not available for geochemical and palynological analysis. Abrupt physical and chemical changes often occur on or across these surfaces, e.g. porosity, permeability and the presence of Fe-rich authigenic minerals such as glauconite and siderite. Greensands deposited in estuarine, barrier bar and shoreforce environments have excellent oil and gas potentail. Early Cretaceous greensand reservoirs from the North West Shelf are best developed where they overlie ravinement surfaces. Recognition of greensands within estuarine, barrier bar and shoreface environments is dependent on the correct identification of facies and the subsequent interpretation of the bounding discontinuities.

The Granular Structure of Two Marine Carbonate Sediments

2018 ◽  
Author(s):  
Ryan D. Beemer ◽  
Alexandre N. Bandini-Maeder ◽  
Jeremy Shaw ◽  
Ulysse Lebrec ◽  
Mark J. Cassidy
Keyword(s):  
3D Models ◽  
Optical Microscope ◽  
Depositional Environments ◽  
Carbonate Sediments ◽  
Micro Computed Tomography ◽  
North West ◽  
The North ◽  
Geological Processes ◽  
Microscope Images ◽  
Hemipelagic Sediment

Calcareous sediments are prominent throughout the low-latitudinal offshore environment and have been known to be problematic for offshore foundation systems. These fascinating soils consist largely of the skeletal remains of single-celled marine organisms (plankton and zooplankton) and can be as geologically complex as their onshore siliceous counter parts. To enable an adequate understanding of their characteristics, in particular, their intra-granular micro-structure, it is important that geotechnical engineers do not forget about the multifaceted biological origins of these calcareous sediments and the different geological processes that created them. In this paper, the 3D models of soils grains generated from micro-computed tomography scans, scanning electeron microscope images, and optical microscope images of two calcareous sediments from two different depositional environments are presented and their geotechnical implications discussed. One is a coastal bioclastic sediment from Perth, Western Australia that is geologically similar to carbonate sediments typically used in micro-mechanics and particle crushing studies in the literature. The other is a hemipelagic sediment from a region of the North West Shelf of Australia that has historically been geotechnically problematic for engineers. The results show there is a marked difference between coastal bioclastic and hemipelagic sediments in terms of geological context and the associated particle micro-structures. This brings into question whether a coastal bioclastic calcareous sediment is a good micro-mechanical substitute for a hemipelagic one.

scholarly journals Geology of the Lower Cretaceous in the Falkebjerg area, Wollaston Forland, northern East Greenland

2020 ◽  
Vol 68 ◽  
pp. 155-169
Author(s):  
Stefan Piasecki ◽  
Jørgen A. Bojesen-Koefoed ◽  
Peter Alsen
Keyword(s):  
Lower Cretaceous ◽  
Depositional Environment ◽  
Depositional Environments ◽  
Petroleum Reservoir ◽  
Dinoflagellate Cysts ◽  
Marine Fauna ◽  
East Greenland ◽  
North West ◽  
The North ◽  
New Good

New data on the Lower Cretaceous Falskebugt Member (Palnatokes Bjerg Formation) and Stratumbjerg Formation in easternmost Wollaston Forland, northern East Greenland, are interpreted here. The type locality of the Falskebugt Member on the north-west corner of the Falkebjerg ridge has been revisited, and additional new good exposures were found in a riverbed just north of Falkebjerg and more in river beds on the plain further to the north, where both the Falskebugt Member and the Stratumbjerg Formation are exposed. Previously, only a limited marine fauna was reported providing a restricted middle Valanginian age of the Falskebugt Member. New fossil faunas in other parts of the Falskebugt Member suggest an early Valanginian – Hauterivian age and confirm lateral correlation with the Albrechts Bugt and Rødryggen Members of the Palnatokes Bjerg Formation. However, in places where the Falskebugt Member is exposed in contact with the lower Stratumbjerg Formation, dinoflagellate cysts from these units indicate Barremian and late Barremian ages, respectively. The stratigraphic range of the combined biostratigraphic data from the Falskebugt Member indicates an early Valanginian – late Barremian age. Dinoflagellate cysts from part of the assemblage in the Stratumbjerg Formation suggest a marginal marine/brackish water depositional environment. Comparable depositional environments are also recorded in upper Barremian sediments on Store Koldewey and in the Ladegårdsåen Formation on Peary Land much farther to the north in Greenland. The dark mudstones of the Stratumbjerg Formation show no potential for generation of liquid hydrocarbons, and the immature and poorly sorted sediments of the Falskebugt Member have little potential as a petroleum reservoir.

SEM and TEM observations of sperm development in the testis of the freshwater fish Oreochromis mossambicus

1990 ◽  
Vol 48 (3) ◽  
pp. 58-59
Author(s):  
Daryl A. Cornish ◽  
George L. Smit
Keyword(s):  
Morphological Characteristics ◽  
Oreochromis Mossambicus ◽  
Breeding Cycle ◽  
Limited Information ◽  
North West ◽  
The North ◽  
Sem And Tem ◽  
Sperm Development ◽  
Ultrastructural Characteristics ◽  
The University

Oreochromis mossambicus is currently receiving much attention as a candidater species for aquaculture programs within Southern Africa. This has stimulated interest in its breeding cycle as well as the morphological characteristics of the gonads. Limited information is available on SEM and TEM observations of the male gonads. It is known that the testis of O. mossambicus is a paired, intra-abdominal structure of the lobular type, although further details of its characteristics are not known. Current investigations have shown that spermatids reach full maturity some two months after the female becomes gravid. Throughout the year, the testes contain spermatids at various stages of development although spermiogenesis appears to be maximal during November when spawning occurs. This paper describes the morphological and ultrastructural characteristics of the testes and spermatids.Specimens of this fish were collected at Syferkuil Dam, 8 km north- west of the University of the North over a twelve month period, sacrificed and the testes excised.

Sign in / Sign up

Export Citation Format

Share Document