Seismic characterization of a blocky mass-transport deposit in the Trealla Limestone Formation, North Carnarvon Basin, Australia

2020 ◽  
Vol 8 (4) ◽  
pp. SR53-SR58
Author(s):  
Laura Ortiz-Sanguino ◽  
Javier Tellez ◽  
Heather Bedle ◽  
Dilan Martinez-Sanchez
Keyword(s):  
Mass Transport ◽  
Seismic Data ◽  
Information Management System ◽  
Data Set ◽  
Differential Dissolution ◽  
Passive Margins ◽  
The North ◽  
Seismic Characterization ◽  
The Individual ◽  
Carnarvon Basin

The deepwater Cenozoic strata in the North Carnarvon Basin, Australia, represent an interval of interest for stratigraphic studies in passive margins settings of mixed siliciclastic-carbonate environments. We have explored the geomorphological characteristics of a mass-transport deposit (MTD) within the Trealla Limestone Formation to describe in detail the differences among the blocks. To characterize the individual geometry and structural configuration of the blocks within the MTD, we used geometric seismic attributes such as coherence, curvature, dip azimuth, and dip magnitude using horizon slices and vertical profiles. The evaluation finds two types of blocks: remnant and glide (or rafted) blocks. Remnant blocks are in situ and stratigraphically continuous fragments with the underlying strata. This type of block is frequently fault-bounded and displays low deformation evidence. Glide blocks are part of the transported material detached from a paleoslope. These blocks are deformed and occasionally appear as “floating” fragments embedded within a chaotic matrix in the MTD. Glide blocks are used as kinematic indicators of the direction of deposition of MTDs. We evaluate these elements in a modern continental analog that resembles a similar setting for a better understanding of the slide occurrence. Geological feature: Glide blocks, North Carnarvon Basin, Australia Seismic appearance: Discrete angular blocks with internal reflectors Alternative interpretations: Differential dissolution in a mixed siliciclastic-carbonate environment Features with a similar appearance: Carbonate buildups, differential dissolution blocks Formation: Trealla Limestone Formation, North Carnarvon Basin Age: Early-Middle Miocene Location: Offshore Northwest Australia, North Carnarvon Basin Seismic data: Obtained from Western Australian Petroleum and Geothermal Information Management System, Draeck 3D seismic data set Analysis tools: Visualization software (Petrel 2019) and attribute performance software (AASPI 6.0)

Stochastic inversion of pressure and saturation changes from time-lapse AVO data

Geophysics ◽  
2006 ◽  
Vol 71 (5) ◽  
pp. C81-C92 ◽  
Author(s):  
Helene Hafslund Veire ◽  
Hilde Grude Borgos ◽  
Martin Landrø
Keyword(s):  
Stochastic Model ◽  
Seismic Data ◽  
Synthetic Data ◽  
Time Lapse ◽  
Bayesian Framework ◽  
Reservoir Modeling ◽  
Data Set ◽  
The North ◽  
Fluid Saturation ◽  
Likelihood Model

Effects of pressure and fluid saturation can have the same degree of impact on seismic amplitudes and differential traveltimes in the reservoir interval; thus, they are often inseparable by analysis of a single stacked seismic data set. In such cases, time-lapse AVO analysis offers an opportunity to discriminate between the two effects. We quantify the uncertainty in estimations to utilize information about pressure- and saturation-related changes in reservoir modeling and simulation. One way of analyzing uncertainties is to formulate the problem in a Bayesian framework. Here, the solution of the problem will be represented by a probability density function (PDF), providing estimations of uncertainties as well as direct estimations of the properties. A stochastic model for estimation of pressure and saturation changes from time-lapse seismic AVO data is investigated within a Bayesian framework. Well-known rock physical relationships are used to set up a prior stochastic model. PP reflection coefficient differences are used to establish a likelihood model for linking reservoir variables and time-lapse seismic data. The methodology incorporates correlation between different variables of the model as well as spatial dependencies for each of the variables. In addition, information about possible bottlenecks causing large uncertainties in the estimations can be identified through sensitivity analysis of the system. The method has been tested on 1D synthetic data and on field time-lapse seismic AVO data from the Gullfaks Field in the North Sea.

Processing, inversion, and interpretation of a 2D seismic data set from the North Viking Graben, North Sea

Geophysics ◽  
2003 ◽  
Vol 68 (3) ◽  
pp. 837-848 ◽  
Author(s):  
Gislain B. Madiba ◽  
George A. McMechan
Keyword(s):  
Seismic Data ◽  
Dynamic Range ◽  
Velocity Ratio ◽  
Total Porosity ◽  
Shear Velocity ◽  
Seismic Section ◽  
Data Set ◽  
Amplitude Variation With Offset ◽  
Fluid Content ◽  
The North

Simultaneous elastic impedance inversion is performed on the 2D North Viking Graben seismic data set used at the 1994 SEG workshop on amplitude variation with offset and inversion. P‐velocity (Vp), S‐velocity (Vs), density logs, and seismic data are input to the inversion. The inverted P‐impedance and S‐impedance sections are used to generate an approximate compressional‐to‐shear velocity ratio (Vp/Vs) section which, in turn, is used along with water‐filled porosity (Swv) derived from the logs from two wells, to generate fluid estimate sections. This is possible as the reservoir sands have fairly constant total porosity of approximately 28 ± 4%, so the hydrocarbon filled porosity is the total porosity minus the water‐filled porosity. To enhance the separation of lithologies and of fluid content, we map Vp/Vs into Swv using an empirical crossplot‐derived relation. This mapping expands the dynamic range of the low end of the Vp/Vs values. The different lithologies and fluids are generally well separated in the Vp/Vs–Swv domain. Potential hydrocarbon reservoirs (as calibrated by the well data) are identified throughout the seismic section and are consistent with the fluid content estimations obtained from alternative computations. The Vp/Vs–Swv plane still does not produce unique interpretation in many situations. However, the critical distinction, which is between hydrocarbon‐bearing sands and all other geologic/reservoir configurations, is defined. Swv ≤ 0.17 and Vp/Vs ≤ 1.8 are the criteria that delineate potential reservoirs in this area, with decreasing Swv indicating a higher gas/oil ratio, and decreasing Vp/Vs indicating a higher sand/shale ratio. As these criteria are locally calibrated, they appear to be valid locally; they should not be applied to other data sets, which may exhibit significantly different relationships. However, the overall procedure should be generally applicable.

Hierarchical exploration of single station seismic data with unsupervised learning

2021 ◽  
Author(s):  
René Steinmann ◽  
Leonard Seydoux ◽  
Michel Campillo
Keyword(s):  
Unsupervised Learning ◽  
Seismic Data ◽  
Acoustic Emissions ◽  
Agglomerative Clustering ◽  
Data Set ◽  
Seismic Waveforms ◽  
The North ◽  
Signal Features ◽  
Single Station ◽  
Seismic Crisis

<p>Seismic datasets contain an enormous amount of information and a large variety of signals with different origins. We usually observe signatures of earthquakes, volcanic and non-volcanic tremors, rockfalls, road and air traffic, atmospheric perturbations and many other acoustic emissions. More and more seismic sensors are deployed worldwide and record the seismic wavefield in a continuous fashion, generating massive volumes of data that cannot be analyzed manually in decent times. Therefore, identifying classes of signals in seismic data with automatic strategies is a crucial stage towards the understanding of the underlying physics of geological objects. For that reason seismologists have developed different tools to detect and classify certain types of signals. Recently, machine learning gained much attention due to its ability to recognize patterns. While supervised learning is a great tool for detecting and classifying signals within already-known classes, it cannot be used to infer new classes of signals, and can be strongly biased by the labels we impose. We here propose to overcome this limitation with unsupervised learning. In this study, we present a new way to explore single-station continuous seismic data with a dendrogram produced by agglomerative clustering. Our method is motivated by the idea that labels in a seismic data set follow a hierarchical order with different levels of details. For example earthquakes belong to the larger class of stationary signals and can be also divided into subclasses with different focal mechanism or magnitudes. We first use a scattering network (a convolutional neural network that makes use of wavelet filers) in order to extract a multi-scale representation of the continuous seismic waveforms. We then select the most meaningful features by means of independent component analysis, and apply an agglomerative clustering on this representation. We finally explore the dendrogram in a systematic way in order to explore the different signal classes revealed by the strategy. We illustrate our method on seismic data continuously recorded in the vicinity of the North-Anatolian fault, in Turkey. During this time period, a seismic crisis with more than 200 micro-earthquakes occurred, together with many other anthropogenic and meteorological events. By exploring the classes revealed by the dendrogram with <em>a posteriori</em> signal features (occurrence, within-class correlations, etc.) we show that the strategy is capable of retrieving the seismic crisis as well as signals related to anthropogenic and meteorogical activities.</p>

Nonstretch moveout correction of long-offset multichannel seismic data for subbasalt imaging: Example from the North Atlantic

Geophysics ◽  
2010 ◽  
Vol 75 (4) ◽  
pp. R83-R91 ◽  
Author(s):  
Hassan Masoomzadeh ◽  
Penny J. Barton ◽  
Satish C. Singh
Keyword(s):  
North Atlantic ◽  
Seismic Data ◽  
Cost Effective ◽  
Data Set ◽  
Velocity Function ◽  
The North ◽  
Long Offset ◽  
The North Atlantic ◽  
New Processing ◽  
Multichannel Seismic Data

We have developed a pragmatic new processing strategy to enhance seismic information obtained from long-offset multichannel seismic data. The conventional processing approach, which treats data on a sample-by-sample basis, is applied at a coarser scale on groups of samples. Using this approach, a reflected event and its vicinity remain unstretched during the normal moveout correction. Isomoveout curves (lines of equal moveout) in the time-velocity panel are employed to apply a constant moveout correction to selected individual events, leading to a nonstretch stack. A zigzag stacking-velocity function is introduced as a combination of segments of appropriate isomoveout curves. By employing a zigzag velocity function, stretching of key events is avoided and thus information at far offset is preserved in the stack. The method is also computationally cost-effective. However, the zigzag stacking-velocity field must be consistent with target horizons. This method of horizon-consistent nonstretch moveout has been applied to a wide-angle data set from the North Atlantic margin, providing improved images of the basement interface, which was previously poorly imaged.

Quantifying the uncertainty in an AVO interpretation

Geophysics ◽  
2002 ◽  
Vol 67 (1) ◽  
pp. 117-125 ◽  
Author(s):  
Richard T. Houck
Keyword(s):  
North Sea ◽  
Seismic Data ◽  
Reflection Coefficients ◽  
Amplitude Variation ◽  
Data Set ◽  
Amplitude Variation With Offset ◽  
Full Characterization ◽  
The North ◽  
The North Sea

Lithologic interpretations of amplitude variation with offset (AVO) information are ambiguous both because different lithologies occupy overlapping ranges of elastic properties, and because angle‐dependent reflection coefficients estimated from seismic data are uncertain. This paper presents a method for quantifying and combining these two components of uncertainty to get a full characterization of the uncertainty associated with an AVO‐based lithologic interpretation. The result of this approach is a compilation of all the lithologies that are consistent with the observed AVO behavior, along with a probability of occurrence for each lithology. A 2‐D line from the North Sea illustrates how the method might be applied in practice. For any data set, the interaction between the geologic and measurement components of uncertainty may significantly affect the overall uncertainty in a lithologic interpretation.

CARNARVON BASIN ARCHITECTURE AND STRUCTURE DEFINED BY THE INTEGRATION OF MINERAL AND PETROLEUM EXPLORATION TOOLS AND TECHNIQUES

2002 ◽  
Vol 42 (1) ◽  
pp. 287 ◽  
Author(s):  
L.L. Pryer ◽  
K.K. Romine ◽  
T.S. Loutit ◽  
R.G. Barnes
Keyword(s):  
Seismic Data ◽  
Structural Model ◽  
Mineral Exploration ◽  
Petroleum Exploration ◽  
Block Rotation ◽  
North West ◽  
The North ◽  
Northern Carnarvon Basin ◽  
Migration Pathways ◽  
Carnarvon Basin

The Barrow and Dampier Sub-basins of the Northern Carnarvon Basin developed by repeated reactivation of long-lived basement structures during Palaeozoic and Mesozoic tectonism. Inherited basement fabric specific to the terranes and mobile belts in the region comprise northwest, northeast, and north–south-trending Archaean and Proterozoic structures. Reactivation of these structures controlled the shape of the sub-basin depocentres and basement topography, and determined the orientation and style of structures in the sediments.The Lewis Trough is localised over a reactivated NEtrending former strike-slip zone, the North West Shelf (NWS) Megashear. The inboard Dampier Sub-basin reflects the influence of the fabric of the underlying Pilbara Craton. Proterozoic mobile belts underlie the Barrow Sub-basin where basement fabric is dominated by two structural trends, NE-trending Megashear structures offset sinistrally by NS-trending Pinjarra structures.The present-day geometry and basement topography of the basins is the result of accumulated deformation produced by three main tectonic phases. Regional NESW extension in the Devonian produced sinistral strikeslip on NE-trending Megashear structures. Large Devonian-Carboniferous pull-apart basins were introduced in the Barrow Sub-basin where Megashear structures stepped to the left and are responsible for the major structural differences between the Barrow and Dampier Sub-basins. Northwest extension in the Late Carboniferous to Early Permian marks the main extensional phase with extreme crustal attenuation. The majority of the Northern Carnarvon basin sediments were deposited during this extensional basin phase and the subsequent Triassic sag phase. Jurassic extension reactivated Permian faults during renewed NW extension. A change in extension direction occurred prior to Cretaceous sea floor spreading, manifest in basement block rotation concentrated in the Tithonian. This event changed the shape and size of basin compartments and altered fluid migration pathways.The currently mapped structural trends, compartment size and shape of the Barrow and Dampier Sub-basins of the Northern Carnarvon Basin reflect the “character” of the basement beneath and surrounding each of the subbasins.Basement character is defined by the composition, lithology, structure, grain, fabric, rheology and regolith of each basement terrane beneath or surrounding the target basins. Basement character can be discriminated and mapped with mineral exploration methods that use non-seismic data such as gravity, magnetics and bathymetry, and then calibrated with available seismic and well datasets. A range of remote sensing and geophysical datasets were systematically calibrated, integrated and interpreted starting at a scale of about 1:1.5 million (covering much of Western Australia) and progressing to scales of about 1:250,000 in the sub-basins. The interpretation produced a new view of the basement geology of the region and its influence on basin architecture and fill history. The bottom-up or basement-first interpretation process complements the more traditional top-down seismic and well-driven exploration methods, providing a consistent map-based regional structural model that constrains structural interpretation of seismic data.The combination of non-seismic and seismic data provides a powerful tool for mapping basement architecture (SEEBASE™: Structurally Enhanced view of Economic Basement); basement-involved faults (trap type and size); intra-sedimentary geology (igneous bodies, basement-detached faults, basin floor fans); primary fluid focussing and migration pathways and paleo-river drainage patterns, sediment composition and lithology.

Mesozoic tectonostratigraphic evolution of the North Carnarvon Basin unlocked using regional 3D seismic

2016 ◽  
Vol 56 (2) ◽  
pp. 564
Author(s):  
Daniel Bishop ◽  
Megan Halbert ◽  
Katherine Welbourn ◽  
Ben Boterhoven ◽  
Stacey Mansfield ◽  
...  
Keyword(s):  
Seismic Data ◽  
Regional Scale ◽  
Depositional Environments ◽  
Single Channels ◽  
Data Sets ◽  
3D Seismic ◽  
The North ◽  
Basin Scale ◽  
3D Seismic Data ◽  
Carnarvon Basin

Interpretation of regional scale merged 3D seismic data sets covering the North Carnarvon Basin has for the first time enabled a detailed description of Mesozoic stratigraphic and structural features on a basin scale. Isoproportional slicing of the data enables direct interpretation of Triassic depositional environments, including contrasting low-stand and high-stand fluvial channel complexes, marginal marine clastic systems and reef complexes. Channels vary dramatically between sinuous-straight single channels within low net:gross floodplain successions, to broad channel belts within relatively high net:gross fluvial successions. The latter can be traced from the inboard part of the basin to the outer areas of the Exmouth Plateau. 3D visualisation and interpretation has demonstrated the huge variety of structural styles that are present, including basement-involved extensional faults, detached listric fault complexes, polygonal faults, and regional scale vertical strike-slip faults with flower structures. Fault trends include north–south, north–northeast to south–southwest, and northeast–southwest, with deformation events occurring mainly between the Rhaetian and Valanginian. Extensional and compressional deformation has created multiple horsts, three-way fault closures, fold belts and associated four-way anticlinal traps. Wrench tectonics may also explain pock-mark trains with the interpreted transfer of over-pressure from Triassic to Early Cretaceous levels. The use of regional scale merged 3D seismic data sets is now shedding light on tectonostratigraphic features on a basin scale that were previously unrecognised or enigmatic on 2D seismic or local 3D seismic data sets.

Shell's integrated quantitative interpretation workflow

2011 ◽  
Vol 51 (2) ◽  
pp. 681
Author(s):  
Frank Glass ◽  
Stephan Gelinsky ◽  
Irene Espejo ◽  
Teresa Santana ◽  
Gareth Yardley
Keyword(s):  
Seismic Data ◽  
Rock Properties ◽  
Well Log ◽  
Reservoir Properties ◽  
North West ◽  
The North ◽  
Fluid Properties ◽  
Well Data ◽  
Acoustic Responses ◽  
Carnarvon Basin

Shell Development Australia is a major asset holder in the Browse Basin and the Carnarvon Basin in the North West Shelf of Australia. In 2007, Shell Development Australia embarked on an integrated quantitative seismic interpretation project related to the Triassic Mungaroo Formation in the Carnarvon Basin. The main objective was to constrain the uncertainties in using seismic data as a predictor for rock and fluid properties of fields and prospects in the basin. This project followed a workflow that has been proven in other basins around the world, whereby the vertical and lateral variability of rock properties of both reservoir and non-reservoir lithologies are captured in general trends. The calculated trends are based on well log extractions of end member lithologies and the input of petrographic information and forward modelling. In combination with a regionally consistent 3D burial model for the estimation of remaining porosity, these established rock trends then allow for a prediction of various acoustic responses of reservoir and pore fill properties. The comparisons between the pre-drill predicted rock properties and the properties encountered after drilling at different reservoir levels have lead to a general confidence that the reservoir properties can be derived from seismic data where well data are not abundant. This increased confidence will play a major part in Shell’s attitude towards appraisal activities and decisions on various development options.

The Brent Field, Block 211/29, UK North Sea

1991 ◽  
Vol 14 (1) ◽  
pp. 63-72 ◽  
Author(s):  
A. P. Struijk ◽  
R. T. Green
Keyword(s):  
North Sea ◽  
Water Depth ◽  
Seismic Data ◽  
Middle Jurassic ◽  
Joint Venture ◽  
Gas Injection ◽  
Lower Jurassic ◽  
Data Set ◽  
North East ◽  
The North

AbstractThe Brent Field was the first discovery in the northern part of the North Sea, and is one of the largest hydrocarbon accumulations in the United Kingdom licence area. There are two separate major accumulations: one in the Middle Jurassic (Brent Group reservoir) and one in the Lower Jurassic/Triassic (Statfjord Formation reservoir). The field lies entirely within UK licence Block 211/29 at latitude 61°N and longitude 2°E. The water depth is 460 ft. The discovery well was drilled in 1971, and six further exploration and appraisal wells were drilled. Seismic data over the Brent Field has been acquired in three separate vintages. The latest acquisition is a 3-D grid recorded in 1986. Reprocessing of the entire 1986 3-D seismic data set was initiated in 1989.The original oil/condensate-in-place, estimated on 1/1/89, is 3500 MMBBL, and the estimated original wet gas-in-place is 6700 TCF. Oil production is now in the decline phase. Average production in 1988 was 334,000 BOPD, with gas sales remaining at the plateau rate of 500 MMSCFD.The field is being developed from four fixed platforms, each providing production, water injection and gas injection facilities for both Brent and Statfjord Formation reservoirs. Gas injection is distributed to achieve an intermediate oil rim development in some reservoir units. The platforms were installed between 1975 and 1978. Production commenced in 1976. The slump faulted crestal areas of both reservoirs have yet to be developed.These crestal areas contain about 5% of the recoverable reserves. Appraisal drilling was carried out in the crest during 1988 and 1989.The Brent Field is located approximately 100 miles north-east of the Shetland Islands and 300 miles NNE of Aberdeen (Fig. 1). The discovery well location is at latitude 61°05'53.87" North longitude 1°41'30.H" East. The water depth is 460 ftThe field comprises two distinct reservoirs, the Brent Group and the Statfjord Formation, which are of Middle Jurassic and Lower Jurassic/Triassic age respectively. The reservoirs occur in a westerly dipping tilted fault block in a fault controlled unconformity trap (Fig. 2).The size of the hydrocarbon bearing area is approximately 10 miles from north to south and 3 miles from east to west (Fig. 3).The reservoirs are in turn divided into seven separate reservoir units; four cycles in the Brent Group reservoir and three units in the Statfjord Formation reservoir. Laterally two major east-west orientated faults divide the field into three separate production areas. A fourth area is the north-south orientated crestal part of both reservoirs, which is faulted and has a series of down faulted slump blocks overlain by 'Reworked Sediment'. This area still has to be developed.The Shell/Esso joint venture North Sea oilfields are named after water and waterside birds. The Brent Field is named after the Brent goose.

Multiphase oblique extension on the North West Shelf of Australia

2021 ◽  
Author(s):  
Chris Elders ◽  
Sara Moron
Keyword(s):  
Seismic Data ◽  
Lower Cretaceous ◽  
Passive Margin ◽  
Rift System ◽  
Active Deformation ◽  
North West ◽  
North East ◽  
The North ◽  
Northern Carnarvon Basin ◽  
Carnarvon Basin

<p>The North West Shelf of Australia has experienced numerous rift events during its prolonged evolution that most likely started in the Lower Palaeozoic and continued through to the formation of the present day passive margin in the Lower Cretaceous.  Carboniferous and Permian is associated with rifting of the Lhasa terrane, a phase extension in the Lower and Middle Jurassic associated with the separation of the Argo terrane Upper Jurassic to Lower Cretaceous extension culminated in the separation of Greater India and Australia.  Investigations based on interpretation of extensive, public domain seismic data, combined with numerical mechanical modelling, demonstrate that crustal structure, rheology and structural fabrics inherited from older events exert a significant control on the architecture of younger rifts.</p><p>Defining the older, more deeply buried rift episodes is challenging, but with seismic data that now images deeper structures more effectively, it is clear that NE-SW oriented Carboniferous to Permian aged rift structures control the overall geometry of the margin.  Variations in the timing, distribution and intensity of that rift may account for some of the complexity that governs the Triassic – a failed arm of the rift system might account for the accumulation of thick sequences of fluvio-delatic sediments in an apparent post-rift setting, while active deformation and igneous activity continued elsewhere on the margin.</p><p>A renewed phase of extension began in the latest Triassic in the western part of the Northern Carnarvon Basin, but became progressively younger to the NE.  High-resolution mechanical numerical experiments show that the dual mode of extension that characterises the Northern Carnarvon Basin, where both distributed and localised deformation occurs at the same time, is best explained by necking and boudinage of strong lower crust, inherited form the Permian rift event, proximal to the continental margin, and a subdued extensional strain rate across the distal extended margin.  A very clear and consistent pattern of ENE oriented extension, which interacts obliquely with the older NE-SW oriented Permian aged structures, is apparent across the whole of the Northern Carnarvon Basin and extends north east into the Roebuck and Browse Basins.  This is at odds with the NW-SE oriented extension predicted by the separation of the Argo terrane which occurs at this time.  This may be explained by the detached style of deformation that characterises the Mesozoic interval.  Alternatively, the separation of Greater India may have exerted a stronger influence on the evolution of the margin during the Jurassic than hitherto recognised.</p>

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