Seismic chronostratigraphy and basin development at a Mid-Cretaceous intrashelf basin margin

2015 ◽  
Vol 3 (2) ◽  
pp. SN1-SN20 ◽  
Author(s):  
Stanley Rich Wharton
Keyword(s):  
Source Rocks ◽  
Main Step ◽  
3D Seismic ◽  
Sea Level Changes ◽  
Seismic Reflection Data ◽  
Seismic Sequences ◽  
Shelf Slope ◽  
Intrashelf Basin ◽  
Shelf Margin ◽  
Basin Margin

The Mid-Cretaceous Wasia Formation represents one of the most productive hydrocarbon carbonate sequences in the Middle East. In Saudi Arabia, limited integrated studies have assessed the complexity and spatial distribution of its reservoir depositional systems near to an intrashelf basin margin. This study was focused on an assessment of its 3D seismic chronostratigraphy by integrating key well and seismic data to evaluate the gross depositional history of the mixed carbonate-clastic system. A seismic chronostratigraphy approach was introduced to assess the geometric relationships of depositional cycles and lithologic associations in response to relative sea-level changes. The main step entailed the correlation of well log chronostratigraphy from core and biostratigraphy interpretations with closely spaced, semiautomatically generated seismic horizons from seismic reflection data. A 3D seismic chronostratigraphy cube was built to interactively assess the basin history through the Mid-Cretaceous stages. Seismic sequences were selected to assess isopachs and gross depositional trends for demarcation of shelf, shelf margin, and slope from horizon attributes including root-mean-square amplitude and frequency decomposition. The results found the oldest Albian Safaniya member to be a generalized low-angle ramp shelf slope with thinning of sequences toward an intrashelf basin. Later, in the Albian, Cenomanian, and Turonian, carbonate factories developed distinct seismic sequences with steepened prograding systems in the Mauddud, Ahmadi/Rumaila, and Mishrif members at the intrashelf basin margin. Generally, areas immediately landward of the shelf margin possessed the most favorable reservoir lithologies of rudist-bearing platform carbonates, with source-rock distribution confined to basinal equivalents of sequences. The seismic chronostratigraphy approach proved to be fundamental to understanding the Wasia carbonate depositional system because it provided a technique to assess the varied stratal architectures of the main productive sequences. The integrated technique represents a unique methodology for exploration targeting of conventional reservoirs and unconventional source rocks.

Dynamics and evolution of continental margin clinoform systems

2020 ◽  
Author(s):  
Gerben de Jager ◽  
Dicky Harishidayat ◽  
Benjamin Emmel ◽  
Ståle Emil Johansen
Keyword(s):  
Sea Level ◽  
Continental Margin ◽  
Water Depth ◽  
Large Scale ◽  
Barents Sea ◽  
Source Rocks ◽  
Sea Level Changes ◽  
Seismic Reflection Data ◽  
Reflection Data ◽  
Geological Processes

<p>Clinoforms are aquatic sedimentary features commonly associated with strata prograding from a shallower water depth into a deeper water depth. They are very sensitive to changes in water depth, rapidly moving along the shelf in response to sea level changes.  By reconstructing the initial clinoform geometry of buried clinoforms, an estimate of the paleo water depth (PWD) can be made. When this is done for several subsequent clinoform sets the amounts and rates of bathymetric changes can be calculated.</p><p>Here we present a novel approach to estimate clinoform parameters and depositional depths for continental margin clinoforms using seismic reflections, wellbore and biostratigraphy data. Seismic interpretation of three relatively east-west regional full-stack seismic reflection data from the continental margin of the western Barents Sea revealed twelve Late Cenozoic horizons. The clinoform shapes have been restored by removing the effects of compaction and flexural isostasy (backstripping). This includes the effects of glacial/interglacial scenarios on horizons with strong glaciomarine seismic indications.</p><p>Based on the reconstructed clinoform geometries we use empirical relationships from literature between clinoform geometry and depositional depth to estimate PWD values. In these analyses it is possible to estimate the PWD of the upper rollover point and the toe point by measuring the bottomset height, foreset height and topset height. A sensitivity analysis study has also been done on several different scenarios, varying elastic thickness, decompaction and net to gross ratio. Comparison with biostratigraphic water depth estimates indicate that PWD estimates revealed from clinoform parameters give reliable results.</p><p>Any mismatch between the backstripped PWD values and the PWD values derived from the clinoform geometry can then be attributed to geological processes not included in the backstripping process. Among others, these could be explained by rifting, thermal effects in the lithosphere, faulting or eustatic sea level changes. This allows the quantification of the magnitude of these large-scale crustal processes through time.</p><p>We will demonstrate that this method can further constrain the PWD on the continental margin clinoform system and thus can help to improve the understanding of the interplay between sedimentary processes and large-scale crustal processes. Furthermore, the PWD estimates will be a reliable input for further analysis of source-to-sink and stratigraphic forward modeling studies as well as reservoir and source rocks prediction on the petroleum development and exploration.</p><p> </p>

scholarly journals Basin margin sediment wedge build out of the Eastern Niger Delta: application of shelf-edge trajectory pattern studies

2021 ◽  
Vol 11 (3) ◽  
pp. 1093-1100
Author(s):  
Okwudiri A. Anyiam ◽  
Nicholas Hoggmascall ◽  
Daniel K. Amogu
Keyword(s):  
Niger Delta ◽  
Sudden Change ◽  
Sediment Flux ◽  
Outer Shelf ◽  
Shelf Edge ◽  
Structural Style ◽  
Shelf Slope ◽  
Trajectory Pattern ◽  
Shelf Margin ◽  
Basin Margin

AbstractThe understanding of how basin margin sediment wedge builds out causes shelf-edge migration with time is approached based on shelf-edge trajectory pattern analysis using a high-resolution mega-merge seismic data from the eastern Niger Delta, Nigeria. The study focuses on a seismic dip transect traversing the Greater Ughelli, Central Swamp, Coastal Swamp and the Shallow Offshore Depobelts of the Niger Delta. On the regional dip transects, shelf-edge sediments occur as clinoform-bearing wedges at and immediately updip of the shelf-slope break. The shelf edge is deeply buried (> 2–4 s, twt), around the Greater Ughelli and Central Swamps. But with changing structural style, sudden change of ascending shelf edge around the Central Swamp was observed. The huge listric growth fault in the Coastal Swamp; around Bonny area, once again cut the shelf edge into half, rotated it along the listric fault and buried it distally. Several depositional packages show low to moderate ascending shelf-edge trajectory with progradational to aggradational clinoform growth that is characterized by thin sand sheets across most of the shelf and upper slope, though few are also characterized by progradational clinoform growth with thick sand on the shelf, upper-tolower slope and basin floor. The deposition is usually on the Outer Shelf Terrace (OST) which is regressive in a flat and rising trajectory style. This study has demonstrated that accommodation and sediment flux are the dominant controls on how the study basin’s sediment wedge built out, whereby limited accommodation promotes sediments with significant shelf-edge advance and descending trajectories, while increasing accommodation promotes ascending trajectories and increased deposition on the outer shelf. The greater sediments on the Outer Shelf Terrace and the shelf margin than on the slope gives more hydrocarbon prospectivity search around the outer shelf and shelf margin.

Controls on the sedimentary characteristics of shelf-edge deltas in a source-to-sink context

2021 ◽  
Author(s):  
Laura Bührig ◽  
Luca Colombera ◽  
Nigel P. Mountney ◽  
William D. McCaffrey
Keyword(s):  
Late Quaternary ◽  
Depositional Environments ◽  
Late Triassic ◽  
Hydrodynamic Process ◽  
Shelf Edge ◽  
Sea Level Changes ◽  
Sedimentary Characteristics ◽  
Shelf Slope ◽  
Source To Sink ◽  
Shelf Margin

<p>Shelf-edge deltas constitute important components of source-to-sink (S2S) systems. They distribute sediment to continental slopes and basin floors from rivers that have prograded across shelves, and due to their scale they form significant sediment accumulations at shelf margins. Because of their intimate relationship with regressive conditions, several geological controls govern their evolution, including relative sea-level changes, sediment budgets, river hydrology, and hydrodynamic processes; these factors are themselves influenced by characteristics of terrestrial catchments and continental shelves, and by climate. Despite their important role in sediment dispersal to shallow- and deep-marine environments, shelf-edge deltas are commonly overlooked in models that describe S2S systems, perhaps because of their relative paucity during the present-day highstand conditions. In subsurface and outcrop, their recognition can be difficult in cases where information with which to constrain the physiographic environment is limited, such that the spatial position of a delta relative to the shelf margin cannot be determined unequivocally.</p><p>This study aims to improve our understanding of controls on the sedimentary characteristics of shelf-edge deltas. For this purpose, >40 shelf-edge deltas of Late Triassic to late Quaternary age from >30 globally-distributed shelf-margin successions have been investigated, utilising literature-derived seafloor-, subsurface- and outcrop data. Following a database approach, sedimentary records have been quantitatively analysed in terms of geometry (e.g. dimensions, thickness, gradients) and facies characteristics (e.g. lithology, sedimentary structures) of depositional environments (e.g. delta top, delta front) and architectural elements (e.g. delta lobes, distributary mouth bars). Specific consideration has been given to assessment of palaeoenvironmental setting (e.g. hydrodynamic process regime, margin type, bathymetric setting, palaeolatitude). Moreover, scaling relationships between these properties and attributes of the S2S system (e.g. fluvial-system and catchment attributes, shelf configuration, shelf-slope transition) have been evaluated. Accordingly, the relative importance of controls on the sedimentary characteristics of shelf-edge deltas has been assessed.</p><p>This analysis demonstrates that environmental factors influence the sedimentary record of shelf-edge deltas via a complex interplay of dynamic processes and physiography of the S2S segments catchment, shelf and slope. Based on these findings, new facies models for shelf-edge delta types are developed, which are placed in the context of S2S linkages. Outcomes of this study aid the identification and classification of shelf-edge deltas and their preserved deposits, as well as the reconstruction of associated environmental conditions from stratigraphic records.</p>

scholarly journals Geomorphological Geometries and High-Resolution Seismic Sequence Stratigraphy of Malay Basin’s Fluvial Succession

2021 ◽  
Vol 11 (11) ◽  
pp. 5156
Author(s):  
Abd Al-Salam Al-Masgari ◽  
Mohamed Elsaadany ◽  
Numair A. Siddiqui ◽  
Abdul Halim Abdul Latiff ◽  
Azli Abu Bakar ◽  
...  
Keyword(s):  
High Resolution ◽  
Sequence Stratigraphy ◽  
Three Dimensional ◽  
Seismic Attributes ◽  
Seismic Facies ◽  
Seismic Sequence ◽  
3D Seismic ◽  
Seismic Sequences ◽  
Seismic Sequence Stratigraphy ◽  
Point Bars

This study identified the Pleistocene depositional succession of the group (A) (marine, estuarine, and fluvial depositional systems) of the Melor and Inas fields in the central Malay Basin from the seafloor to approximately −507 ms (522 m). During the last few years, hydrocarbon exploration in Malay Basin has moved to focus on stratigraphic traps, specifically those that existed with channel sands. These traps motivate carrying out this research to image and locate these kinds of traps. It can be difficult to determine if closely spaced-out channels and channel belts exist within several seismic sequences in map-view with proper seismic sequence geomorphic elements and stratigraphic surfaces seismic cross lines, or probably reinforce the auto-cyclic aggregational stacking of the avulsing rivers precisely. This analysis overcomes this challenge by combining well-log with three-dimensional (3D) seismic data to resolve the deposition stratigraphic discontinuities’ considerable resolution. Three-dimensional (3D) seismic volume and high-resolution two-dimensional (2D) seismic sections with several wells were utilized. A high-resolution seismic sequence stratigraphy framework of three main seismic sequences (3rd order), four Parasequences sets (4th order), and seven Parasequences (5th order) have been established. The time slice images at consecutive two-way times display single meandering channels ranging in width from 170 to 900 m. Moreover, other geomorphological elements have been perfectly imaged, elements such as interfluves, incised valleys, chute cutoff, point bars, and extinction surfaces, providing proof of rapid growth and transformation of deposits. The high-resolution 2D sections with Cosine of Phase seismic attributes have facilitated identifying the reflection terminations against the stratigraphic amplitude. Several continuous and discontinuous channels, fluvial point bars, and marine sediments through the sequence stratigraphic framework have been addressed. The whole series reveals that almost all fluvial systems lay in the valleys at each depositional sequence’s bottom bars. The degradational stacking patterns are characterized by the fluvial channels with no evidence of fluvial aggradation. Moreover, the aggradation stage is restricted to marine sedimentation incursions. The 3D description of these deposits permits distinguishing seismic facies of the abandoned mud channel and the sand point bar deposits. The continuous meandering channel, which is filled by muddy deposits, may function as horizontal muddy barriers or baffles that might isolate the reservoir body into separate storage containers. The 3rd, 4th, and 5th orders of the seismic sequences were established for the studied succession. The essential geomorphological elements have been imaged utilizing several seismic attributes.

THE STRUCTURAL DEVELOPMENT AND HYDROCARBON POTENTIAL OF PALAEOZOIC SOURCE ROCKS IN THE ADAVALE BASIN REGION

1984 ◽  
Vol 24 (1) ◽  
pp. 393 ◽  
Author(s):  
V. L. Passmore ◽  
M. J. Sexton
Keyword(s):  
Middle Devonian ◽  
Oil And Gas ◽  
Structural Features ◽  
Source Rocks ◽  
Geochemical Data ◽  
Mature Stage ◽  
Hydrocarbon Generation ◽  
Structural Development ◽  
Seismic Reflection Data ◽  
Basin Region

The Adavale Basin of southwestern Queensland consists of a main depression and several isolated synclinal extensions, traditionally referred to as troughs. The depressions and troughs are erosional remnants of a once more extensive Devonian depositional basin, and are now completely buried by sediments of the overlying Cooper, Galilee and Eromanga Basins. Geophysical and drilling investigations undertaken since 1959 are the only source of information on the Adavale Basin. A single sub-economic discovery of dry gas at Gilmore and a few shows of oil and gas are the only hydrocarbons located in the basin to date.In 1980, the Bureau of Mineral Resources in cooperation with the Geological Survey of Queensland commenced a major, multidisciplinary investigation of the basins in southwestern Queensland. Four long (> 200 km) seismic lines from this study over the Adavale Basin region and geochemical data from 20 wells were used to interpret the Adavale Basin's development and its present hydrocarbon potential.The new seismic reflection data allow the well-explored main depression to be correlated with the detached troughs, some of which have little or no well information. The BMR seismic data show that these troughs were previously part of one large depositional basin in the Devonian, the depocentre of which lay east of a north-trending hingeline. Structural features and Devonian depositional limits and patterns have been modified from earlier interpretations as a result of the new seismic coverage. The maximum sediment thickness is re-interpreted to be 8500 m, considerably thicker than previous interpretation.recognised. The first one, a diachronous Middle Devonian unconformity, is the most extensive, and reflects the mobility of the basement during the basin's early history. The second unconformity within the Late Devonian Buckabie Formation reveals that there were two phases of deformation of the basin sediments.The geochemical results reported in this study show that most of the Adavale Basin sediments have very low concentrations of organic carbon and hydrocarbon fractions. Maturity profiles indicate that the best source rocks of the basin are now in the mature stage for hydrocarbon generation. However, at Gilmore and in the Cooladdi Trough, they have reached the dry gas stage. The maturity data provide additional evidence for the marked break in deposition and significant erosion during the Middle Devonian recognised on the seismic records, and extend the limits of this sedimentary break into the northern part of the main depression.Hydrocarbon potential of the Adavale Basin is fair to poor. In the eastern part of the basin, where most of the data are available, the prospects are better for gas than oil. Oil prospectivity may be improved in any exinite-rich areas that exist farther west, where palaeo-temperatures were lower.

SEQUENCE STRATIGRAPHY OF THE EASTERN OFFICER AND ARROWIE BASINS: A FRAMEWORK FOR CAMBRIAN OIL SEARCH

1991 ◽  
Vol 31 (1) ◽  
pp. 177 ◽  
Author(s):  
D. I. Gravestock ◽  
J.E. Hibburt
Keyword(s):  
Carbonate Reservoir ◽  
Source Rocks ◽  
Tectonic Activity ◽  
Reservoir Quality ◽  
Organic Carbon Content ◽  
The North ◽  
Subaerial Exposure ◽  
Potential Source ◽  
Shelf Slope ◽  
Playa Lake

The Early Cambrian eastern Officer and Arrowie Basins share a common sequence stratigraphic framework despite their contrasting settings. The Arrowie Basin was initially a shallow marine shelf between two land masses with moderate to abrupt shelf-ramp and shelf-slope profiles deepening to the north and south. Tectonic activity subsequently restricted open marine access to the north resulting in evaporite and red bed deposition. In the eastern Officer Basin epeiric sea sediments had open marine access only to the northeast. The palaeoslope was low and surrounding land supplied abundant siliciclastics. Following marine withdrawal alkaline playa lake and evaporitic mudflat deposits spread across the hinterland. Potential source rocks in the Arrowie Basin are thick transgressive and early high-stand deposits of the lowest three sequences. Organic carbon content may be highest (on slender evidence) where marine circulation was restricted. Carbonate reservoir quality on the shelf depends on subaerial exposure during marine lowstands. Prograding highstand sands, carbonate grainstones, and syntectonic channel deposits have untested reservoir potential. In the eastern Officer Basin potential source rocks are thin but widespread. Oil has been generated in the playa lake sediments. Fluvial, aeolian and shoreline sandstones, and those interbedded with carbonates, have excellent reservoir characteristics. The interbedded sands are thin but may be grouped near sequence boundaries. Lowstand carbonate breccias have generally unpredictable reservoir quality. Major differences in source and reservoir bed distribution between these basins, which share the same cycles of relative sea level change, are: palaeoslope, proximity to open marine conditions, duration of subaerial exposure and availability of terrigenous clastics.

TECTONOSTRATIGRAPHIC EVOLUTION OF THE SOUTH-EAST GIPPSLAND BASIN

1991 ◽  
Vol 31 (1) ◽  
pp. 116 ◽  
Author(s):  
B.A. Duff ◽  
N.G. Groilman ◽  
D.J. Mason ◽  
J.M. Questiaux ◽  
D.S. Ormerod ◽  
...  
Keyword(s):  
Sea Level ◽  
Normal Faults ◽  
Plate Boundaries ◽  
Sea Level Changes ◽  
The South ◽  
Seismic Sequences ◽  
Controlled Deposition ◽  
Global Sea Level ◽  
Sequence Boundaries ◽  
Gippsland Basin

Evolution of the south-east Gippsland Basin since ca. 96 Ma has been governed by the interaction of three distinct processes:re-organisation of regional plate boundaries at 96, 80 and 50 Ma, registered as major angular unconformities or megasequence boundaries;intra-basin response of cover to basement-controlled deformational phases, registered as the sequence boundaries within these megasequences; andthe more subtle balance between regressive sedimentation associated with these phases and the transgressive deposition associated with longer-term eustatic sea level rises.The Golden Beach Megasequence (seismic sequences UK1 and UK2) accumulated syntectonically in an extensional setting characterised by an orthogonal array of north-northeast trending transfer faults and associated normal faults. Major compressional tectonism at ca. 80 Ma terminated this regime, initiating a modified mosaic of stratotectonic domains which controlled deposition of the Latrobe Megasequence.The seismic sequences within this megasequence display two types of cyclicity distinguishing intra-Campanian to Top Maastrichtian sequences (UK3-UK5) from early Tertiary sequences (PL1, PL2 and EO1). The sequence boundaries are considered to be the expression of recurrent compressive deformational phases. They are demonstrable as angular unconformities in transpressional and pull-apart structures in domains within which deformation was focused over the older extensional grain.The ca. 50 Ma Top Latrobe megasequence boundary appears to mark the transition from a basement-coupled deformational style characteristic of the Latrobe Megasequence, to a basement-decoupled inversion style of deformation during deposition of the Seaspray Megasequence (post-50 Ma).Seismic sequence boundaries, at least within basins such as the Gippsland, are therefore the stratigraphic expression of deformational phases rather than signatures of global sea-level changes. Eustacy is not invariably a shorter-term process than basin tectonism, nor is it the sole or main determinant of depositional style.

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