STRUCTURE AND DEVELOPMENT OF THE SOUTHERN MARGIN OF AUSTRALIA

1975 ◽  
Vol 15 (1) ◽  
pp. 33 ◽  
Author(s):  
M. G. Boeuf ◽  
H. Doust
Keyword(s):  
Continental Margin ◽  
Seismic Data ◽  
Lower Cretaceous ◽  
Rift Valley ◽  
Upper Cretaceous ◽  
Structural Data ◽  
Theoretical Models ◽  
Palaeomagnetic Data ◽  
Geological Evolution ◽  
Seismic Records

Off the southern coast of Australia, exploration results and deep-water reconnaissance seismic data support the concept of an aseismic Atlantic-type continental margin. Characteristic is a sedimentary wedge which extends from the shelf to the abyssal plains and includes crustal elements of continental and oceanic origin.Oceanward, a continuous level of diffractions ascribed to the top of oceanic crust can be observed on seismic records, steeply dipping beneath the continental rise towards a smooth, flat, often faulted reflector which is correlated with top Precambrian or Palaeozoic continental basement.The sedimentary wedge which overlies the block-faulted and collapsed continental basement is subdivided by unconformities into: (a) a continental Lower Cretaceous unit and a fluviodeltaic unit of Upper Cretaceous-Danian age which are taken to represent rift valley stages of deposition controlled by extensional tectonics and (b) a post-breakup sequence of Tertiary units representing regional collapse and out-building of the shelf. The Upper Cretaceous sequence is missing along much of the continental edge where Tertiary sediments appear to rest directly on the Lower Cretaceous unit.Our interpretation suggests that a prolonged period of uplift took place along the axis of the rift valley prior to continental break-up. On the basis of palaeomagnetic data and biostratigraphic analysis the breakup phase started in the Upper Paleocene.From the continent outward several structural zones can commonly be recognised: (a) a zone of shallow basement with a thin Lower Cretaceous cover normally faulted and overlain by thin gently dipping Tertiary beds, (b) a zone of faulted and landwards tilted basement blocks and Lower Cretaceous sediments overlain (sometimes with clear unconformity) by thick Upper Cretaceous sediments, (c) a zone of thick, moderately deformed Tertiary sediments whose axis of deposition is generally offset to the south of the Upper Cretaceous basinal axis, (d) a zone of rotational faults and associated toe thrusts affecting the Cretaceous sediments and apparently related to the time of margin collapse, (e) an area of little disturbed Cretaceous and Tertiary sediments overlying continental basement. This zone extends into the "magnetic quiet zone" which is therefore believed to be, at least in part, a collapsed portion of the continental margin adjacent to oceanic crust.The interpretation of the geological evolution of the southern Australian margin based on the stratigraphic and structural data presently available can be related to current theoretical models on continental margin development.

Old challenges, new developments and new plays in Irish offshore exploration

2016 ◽  
Vol 8 (1) ◽  
pp. 171-185 ◽  
Author(s):  
Patrick M. Shannon
Keyword(s):  
Data Quality ◽  
Seismic Data ◽  
Lower Cretaceous ◽  
New Developments ◽  
Commercial Success ◽  
Petroleum Systems ◽  
Technological Advances ◽  
Geological Evolution ◽  
Exploration Drilling ◽  
Atlantic Margin

AbstractMore than 46 years of exploration in the Irish offshore has yielded modest commercial success. However, working petroleum systems have been proven in all the offshore basins. The pace of exploration has been controlled by: (a) data quality and technological advances; (b) geological understanding and plays; (c) fiscal and infrastructural environments; and (d) international conditions. Irish offshore exploration drilling started in the Celtic Sea basins in 1970 and the region has seen a recent renewal of exploration interest, stimulated by new and much improved seismic data. In the Atlantic margin basins west of Ireland, there has been a recent significant improvement in the understanding of the geological evolution and petroleum systems, especially in the hyperextended basins such as the Porcupine and Rockall basins. Here the major targets of current exploration are stratigraphic traps at Lower Cretaceous and Lower Cenozoic levels. The application of new and innovative seismic and other geophysical technologies in a number of the Irish offshore basins has led to significant enhancement in data quality and in resolving imaging challenges. Combined with recent geological learnings, they offer renewed hope for exploration success in the Irish offshore basins.

DEPOSITIONAL ENVIRONMENTS AND GEOTECTONIC FRAMEWORK: SOUTHERN AUSTRALIAN CONTINENTAL MARGIN

1976 ◽  
Vol 16 (1) ◽  
pp. 25 ◽  
Author(s):  
I. Deighton ◽  
D.A. Falvey ◽  
D.J. Taylor
Keyword(s):  
Continental Margin ◽  
Rift Valley ◽  
Upper Cretaceous ◽  
Deep Ocean ◽  
Ocean Basin ◽  
Depositional Environments ◽  
Ocean Current ◽  
Spreading Ridge ◽  
Marine Influence ◽  
Sea Floor Spreading

Three principal phases occurred in the development of the basins of the southern Australian continental margin: epi-continental, marginal continental and oceanic. These correspond generally to the phases of margin development proposed by Falvey (1974): pre-rift, rift valley, and post-breakup; but tectonic and depositional transitions are not necessarily contemporaneous.Prior to the Upper Cretaceous, the region of the present day southern Australian margin lay well within the Eastern Gondwanaland continent, essentially barred from deep ocean basins. During the Upper Cretaceous the series of epicontinental basins was increasingly subjected to marine breakthroughs. Thus marine ingressive horizons were deposited along an incipient rift valley between the primitive Indian Ocean and Tasman Sea. Rift valley subsidence, possibly related to deep crustal metamorphism, was most significant on the flanks of the rift zone. Further marine influence during the Paleocene ('infra-breakup') and early Eocene corresponded to the onset of seafloor spreading between Australia and Antarctica. The neo-breakup phase is dominated by shelf and plateau subsidence and spreading ridge development, with topography influencing ocean current. The changing palaeogeography can be accurately illustrated by computer-derived reconstructions based on quantitative sea-floor spreading data. Quantitative thermal uplift/subsidence models can be used to estimate post-breakup water depth of the subsiding ocean basin and the continental margin. A complex pattern of transgressive continental deposition and submarine erosion diminished with the gradual widening of the Southern Ocean and the establishment of circumpolar ocean current paths. Oceanic basins dominated the margin through the Neogene.

scholarly journals Using Chaos and Ant Track Attributes to Recognize The Faulting Systems and Subtle Faults of a Jurassic - Cretaceous Sedimentary Packages in Merjan_West Kifl Oil Fields - Central Iraq

2019 ◽  
pp. 1350-1361
Author(s):  
Mohammed Sadi Fadhil ◽  
Ali M. Al-Rahim
Keyword(s):  
Gravitational Collapse ◽  
Seismic Data ◽  
Lower Cretaceous ◽  
Upper Cretaceous ◽  
Three Dimensional ◽  
Lower Jurassic ◽  
Passive Margin ◽  
Oil Fields ◽  
Normal Faults ◽  
Seismic Sections

Study of three dimensional seismic data of Merjan area-central Iraq has shown that the Jurassic – Cretaceous succession is affected by faulting system. Seven major normal faults were identified and mapped. Synthetic traces have been calculated by using sonic and density log data of the well Me-1.Two exploration wells were drilled in the area Me-1 and Wkf-1 wells, the distance between them is 15.82 km. Discussion about the effect of this system on the sedimentary package has been presented. The tight faults that couldn’t be distinguished it on seismic sections were determined using seismic attributes. They have different strike and limited in their vertical and horizontal extension. They are system facilitates the movement or migration of the fluid across the stratigraphic column in the study area. Faulting framework can be divided into two groups: the first affects the Jurassic and lower Cretaceous rocks and the second effect the upper Cretaceous and lower Tertiary rocks. The first group is associated with the post rift thermal sag, passive margin progradation and gravitational collapse (lower Jurassic – upper Cretaceous (Turonian) 022 – 93 Ma); approximately Sargelue – NahrUmr depositional time. The second group is few and is associated with the rifting creating the Euphrates graben (Late Turonian – Maastrichtian 90 – 70 Ma) approximately Tanuma shale / Sadi – Shiranish) depositional time.

Regularization and datuming of seismic data by weighted, damped least squares

Geophysics ◽  
2006 ◽  
Vol 71 (5) ◽  
pp. U67-U76 ◽  
Author(s):  
Robert J. Ferguson
Keyword(s):  
Least Squares ◽  
Seismic Data ◽  
Synthetic Data ◽  
Real Data ◽  
Structural Data ◽  
Irregular Sampling ◽  
Data Set ◽  
Near Surface ◽  
Damped Least Squares ◽  
Wavefield Extrapolation

The possibility of improving regularization/datuming of seismic data is investigated by treating wavefield extrapolation as an inversion problem. Weighted, damped least squares is then used to produce the regularized/datumed wavefield. Regularization/datuming is extremely costly because of computing the Hessian, so an efficient approximation is introduced. Approximation is achieved by computing a limited number of diagonals in the operators involved. Real and synthetic data examples demonstrate the utility of this approach. For synthetic data, regularization/datuming is demonstrated for large extrapolation distances using a highly irregular recording array. Without approximation, regularization/datuming returns a regularized wavefield with reduced operator artifacts when compared to a nonregularizing method such as generalized phase shift plus interpolation (PSPI). Approximate regularization/datuming returns a regularized wavefield for approximately two orders of magnitude less in cost; but it is dip limited, though in a controllable way, compared to the full method. The Foothills structural data set, a freely available data set from the Rocky Mountains of Canada, demonstrates application to real data. The data have highly irregular sampling along the shot coordinate, and they suffer from significant near-surface effects. Approximate regularization/datuming returns common receiver data that are superior in appearance compared to conventional datuming.

Radon Transform Removes Correlation Noise Produced by Vibroseis

2014 ◽  
Vol 672-674 ◽  
pp. 1964-1967
Author(s):  
Jun Qiu Wang ◽  
Jun Lin ◽  
Xiang Bo Gong
Keyword(s):  
Radon Transform ◽  
Seismic Data ◽  
Cross Correlation ◽  
Random Noise ◽  
Seismic Record ◽  
Electromagnetic Drive ◽  
Seismic Records ◽  
Correlation Noise

Vibroseis obtained the seismic record by cross-correlation detection calculation. compared with dynamite source, cross-correlation detection can suppress random noise, but produce more correlation noise. This paper studies Radon transform to remove correlation noise produced by electromagnetic drive vibroseis and impact rammer. From the results of processing field seismic records, we can see that Radon transform can remove correlation noise by vibroseis, the SNR of vibroseis seismic data is effectively improved.

Combined Application of Deep Boundary Detection Tool, Multilayer Data Inversion and 3D Visualization of Seismic Data in Real Time for Geosteering on the Oilfield in the Russian Federation

2021 ◽  
Author(s):  
Chingis Oshakbayev ◽  
Roman Romanov ◽  
Valentin Vlassenko ◽  
Simon Austin ◽  
Sergey Kovalev ◽  
...  
Keyword(s):  
Real Time ◽  
Oil Recovery ◽  
Seismic Data ◽  
3D Visualization ◽  
Structural Data ◽  
Boundary Detection ◽  
Integrated Analysis ◽  
Horizontal Section ◽  
Recovery Method ◽  
Detection Tool

Abstract Currently drilling of horizontal wells is a common enhanced oil recovery method. Geosteering services are often used for accurate well placement, which makes it possible to achieve a significant increase in production at relatively low cost. This paper describes the result of using seismic data in three-dimensional visualization for high-quality geosteering using a deep boundary detection tool and multilayer inversion in real time. Crossing the top of the reservoir while drilling horizontal sections at the current oilfield is unacceptable, due to the presence of reactive mudstones. In case of crossing the top of reservoir, further work on running and installing the liner becomes impossible due to instability and may lead to well collapse. Based on prewell analysis of the structural data, the well was not supposed to approach the top of the target formation along the planned profile. However, while preparing geosteering model and analyzing seismic data it became possible to reveal that risk, elaborate its mitigation and eventually increase the length of the horizontal section. Such integrated analysis made it possible to maintain the wellbore within the target reservoirs, as well as to update the structural bedding of the top based on the multilayer inversion results.

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