scholarly journals Application of seismic stratigraphy in reservoir characterisation: a case study of the passive margin deposits of the northern Orange Basin, South Africa

2020 ◽  
Author(s):  
Chris Adesola Samakinde ◽  
Jan Marinus Van Bever Donker ◽  
Ray Durrheim ◽  
Musa Manzi
Keyword(s):  
South Africa ◽  
Mass Transport ◽  
Gamma Ray ◽  
Sedimentary Basins ◽  
Seismic Stratigraphy ◽  
Passive Margin ◽  
Seismic Facies ◽  
Depositional Sequences ◽  
Seismic Reflectors ◽  
Mass Transport Deposits

AbstractThe Barremian-Cenozoic depositional sequences in the northern Orange Basin, SW, South Africa, were investigated using the principles of seismic stratigraphy to understand the interplay of tectonics and sedimentary processes in the distribution of potential hydrocarbon reservoirs. A seismic stratigraphic workflow (seismic sequence, seismic facies and lithofacies analysis) was completed by utilising three seismic lines (L1, L2 and L3) tied to Wireline data (gamma, checkshots and sonic) in two exploration wells (A1 and A2). Seven depositional sequences were mapped followed by the creation of lithofacies log interpreted from the gamma-ray log (GR) by setting maximum GR value at 60 API for Sandstone, 60–100 API for Siltstone and above 100 API for Shale. Six seismic facies units are recognised based on internal geometry and configurations of the seismic reflectors; Tangential-Oblique (SF1), Hummocky (SF2), Wavy-Parallel (SF3), Chaotic (SF4), Sub-parallel/parallel (SF5) and Divergent (SF6). SF4 is dominant within the Barremian-Aptian sequence and expressed in an incised valley fill, suggesting mass transport deposition accompanied by strong hydrodynamic conditions. Evidence of sedimentary basins progradation is seen within the Late-Albian-Turonian sequences, because of the occurrences of SF2, SF6 and SF 4 facies. SF5 facies is prominent in the Maastrichtian/Campanian sequence, indicating that the deposition of sediments may have been accompanied by uniform margin subsidence after the Late-Cretaceous uplift of the Africa margin. The occurrence of SF1 and SF4 facies within the Cenozoic sequence indicates terrigenous pro-deltaic deposits and mass transport deposits, respectively. Further results from seismic-lithofacies modelling reveal that sand deposits of Barremian-Aptian (SF4 facies unit) and Albian sequences (SF2 and SF6 facies units) are potential stratigraphic reservoirs in this part of the basin.

Slumps Mass-Transport Deposits in the Brazilian Continental Margin Deep Water: Offshore Potiguar Basin, NE Brazil.

2020 ◽  
Author(s):  
Yoe Perez ◽  
Julia Fonseca ◽  
Helenice Vital ◽  
Andre Silva ◽  
David Castro
Keyword(s):  
Mass Transport ◽  
Continental Slope ◽  
Continental Margin ◽  
Deep Water ◽  
Negative Impact ◽  
Water Area ◽  
Passive Margin ◽  
Rift System ◽  
Potiguar Basin ◽  
Mass Transport Deposits

<p>The Brazilian Continental Margin (BEM) deep-water regions contain important geological features that need advance in their characterization. Mass-transport deposits (MTD) are important not only by their significance in the sedimentary but also because of their negative impact economically. A slump is a coherent mass of sediment that moves on a concave-up glide plane and undergoes rotational movements causing internal deformation and one of the basic types of MTD. The study area comprises part of the offshore Potiguar Basin in NE Brazil, on the distal eastern portion of the Touros High and Fernando de Noronha Ridge. This portion of the Potiguar Basin comprises a transform rift system that has evolved into a continental passive margin. This basin represents an important location related to the breakup between South America and Africa. The database used in this work included 2D post-stack time-migrated seismic profiles from the Brazilian Agency of Petroleum, Natural Gas, and Biofuels (ANP). The slumps reflectors are identified on the continental shelf profiles in form of present clinoform configuration, medium to high continuity, high amplitudes, and medium to high frequencies, representing a sigmoidal oblique complex prograding reflector. The slump scars at the continental slope indicate that this is a gravitationally unstable area that will eventually collapse, resulting in erosional features on the continental slope and deposition on the continental rise. Our results provide some insights regarding MDT slumps sedimentary evolution in the BEM deep water area as well as their interrelation with other sedimentary deposits.</p>

scholarly journals Diffraction imaging of sedimentary basins: An example from the Porcupine Basin 

2021 ◽  
Author(s):  
Brydon Lowney ◽  
Lewis Whiting ◽  
Ivan Lokmer ◽  
Gareth O'Brien ◽  
Christopher Bean
Keyword(s):  
Mass Transport ◽  
Seismic Data ◽  
Sedimentary Basins ◽  
Fracture Network ◽  
Generative Adversarial Network ◽  
Adversarial Network ◽  
Porcupine Basin ◽  
Diffraction Imaging ◽  
Flow Pathways ◽  
Mass Transport Deposits

<p>Diffraction imaging is the technique of separating diffraction energy from the source wavefield and processing it independently. As diffractions are formed from objects and discontinuities, or diffractors, which are small in comparison to the wavelength, if the diffraction energy is imaged, so too are the diffractors. These diffractors take many forms such as faults, fractures, and pinch-out points, and are therefore geologically significant. Diffraction imaging has been applied here to the Porcupine Basin; a hyperextended basin located 200km to the southwest of Ireland with a rich geological history. The basin has seen interest both academically and industrially as a study on hyperextension and a potential source of hydrocarbons. The data is characterised by two distinct, basin-wide, fractured carbonates nestled between faulted sandstones and mudstones. Additionally, there are both mass-transport deposits and fans present throughout the data, which pose a further challenge for diffraction imaging. Here, we propose the usage of diffraction imaging to better image structures both within the carbonate, such as fractures, and below.</p><p>To perform diffraction imaging, we have utilised a trained Generative Adversarial Network (GAN) which automatically locates and separates the diffraction energy on pre-migrated seismic data. The data has then been migrated to create a diffraction image. This image is used in conjunction with the conventional image as an attribute, akin to coherency or semblance, to identify diffractors which may be geologically significant. Using this technique, we highlight the fracture network of a large Cretaceous chalk body present in the Porcupine, the internal structure of mass-transport deposits, potential fan edges, and additional faults within the data which may affect fluid flow pathways.</p>

scholarly journals Seismic expression of depositional elements associated with a strongly progradational shelf margin: northern Santos Basin, southeastern Brazil

2016 ◽  
Vol 46 (4) ◽  
pp. 585-603 ◽  
Author(s):  
Fábio Berton1* ◽  
◽  
Fernando Farias Vesely
Keyword(s):  
Mass Transport ◽  
Progressive Increase ◽  
Seismic Facies ◽  
Southeastern Brazil ◽  
Submarine Channels ◽  
Base Level ◽  
Equilibrium Profile ◽  
Mass Transport Deposits ◽  
Shelf Margin ◽  
Depositional Elements

ABSTRACT: Seismic facies analysis and seismic geomorphology are important tools for the analysis of depositional elements in subsurface. This paper aimed to investigate the character and genesis of depositional elements and erosive features associated with an Eocene progradational shelf margin in northern Santos Basin. Identified seismic facies are interpreted as shelf-margin deltas/shoreface deposits, tangential (oblique) clinoforms, sigmoidal clinoforms, topset reflectors, mass-transport deposits and turbidites. These facies are grouped into four associations representing periods of relatively constant environmental conditions. Association 1 is composed of shelf-margin deltas/shoreface deposits, tangential clinoforms and extensive sand-rich turbidites disposed as submarine channels and frontal splays. A progressive increase in clinoform angle within this association has been identified, culminating in high-relief sigmoidal clinoforms with less voluminous turbidites of facies association 2. Association 3 is composed by subparallel to divergent topset reflectors, interpreted as continental to shelfal deposits placed during base-level rises. These are always truncated basinward by slump scars, formed as a consequence of sediment overload at the shelf margin during aggradations. Association 4 is composed of sigmoidal clinoforms, mass-transport deposits and turbidites. Early clinoforms are steeper as a consequence of the topography of the slump scars. Subsequently, dip angles become progressively gentler as the system approach to the equilibrium profile. The steep physiography was favorable for canyon incision, which played an important role in turbidite deposition. Mass-transport deposits, formed subsequent to slope collapse, are composed of mud-rich diamictites, and show strong internal deformation.

Assessment of the effect of mass-transport deposits on fault propagation in Penobscot area, offshore Nova Scotia

2018 ◽  
Vol 477 (1) ◽  
pp. 121-131 ◽  
Author(s):  
Tuviere Omeru ◽  
Samson I. Bankole ◽  
Byami A. Jolly ◽  
Obafemi S. Seyi ◽  
Joses B. Omojola
Keyword(s):  
Nova Scotia ◽  
Mass Transport ◽  
Three Dimensional ◽  
Seismic Facies ◽  
Thickness Variation ◽  
Fault Propagation ◽  
Seismic Profiles ◽  
History Of ◽  
Throw Distance ◽  
Mass Transport Deposits

AbstractThree-dimensional (3D) seismic data and well logs from the Penobscot area, located within the Scotian Basin offshore Nova Scotia, are used to assess the role of mass-transport deposits (MTDs) on fault propagation. Four MTDs characterized by chaotic seismic facies were mapped, with the earliest hosted by the Late Cretaceous–Recent Dawson Canyon Formation and latest three hosted by the Banquereau Formation. Two types of faults were also mapped. R-faults are regional faults that cut across all the interpreted MTDs in the study area, while P-faults are polygonal faults that cut across MTDs 2 and 3 but tip out at the basal surfaces of MTDs 4 and 2. Representative seismic profiles and isochron maps of the MTDs and throw–depth (T–z) and throw–distance (T–x) plots allows us to distinguish the families and propagation history of the faults. Our results show that fault propagation is not affected by the presence or thickness variation of MTDs, and is also unaffected by lithological contrast in the Penobscot area of the Nova Scotian Shelf.

scholarly journals Geostatistical characterization of internal structure of mass-transport deposits from seismic reflection images and borehole logs

2019 ◽  
Vol 221 (1) ◽  
pp. 318-333
Author(s):  
Jonathan Ford ◽  
Angelo Camerlenghi
Keyword(s):  
Mass Transport ◽  
Internal Structure ◽  
Seismic Reflection ◽  
Slope Failure ◽  
Random Medium ◽  
Seismic Facies ◽  
Strain History ◽  
Borehole Data ◽  
Mass Transport Deposits ◽  
Scale Length

SUMMARY Seismic reflection images of mass-transport deposits often show apparently chaotic, disorded or low-reflectivity internal seismic facies. The lack of laterally coherent reflections can prevent horizon-based interpretation of internal structure. This study instead inverts for geostatistical parameters which characterize the internal heterogeneity of mass-transport deposits from depth-domain seismic reflection images. A Bayesian Markov Chain Monte Carlo inversion is performed to estimate posterior probability distributions for each geostatistical parameter. If the internal heterogeneity approximates an anisotropic von Kármán random medium these parameters can describe the structural fabric of the imaged mass-transport deposit in terms of lateral and vertical dominant scale lengths and the Hurst number (roughness). To improve the discrimination between vertical and lateral dominant scale lengths an estimate of the vertical dominant scale length from a borehole is used as a prior in the inversion. The method is first demonstrated on a synthetic multichannel seismic reflection image. The vertical and lateral dominant scale lengths are estimated with lower uncertainty when data from a synthetic borehole data are included. We then apply the method to a real data example from Nankai Trough, offshore Japan, where a large mass-transport deposit is imaged in a seismic profile and penetrated by a borehole. The results of the inversion show a downslope shortening in lateral scale length, consistent with progressive down-slope disaggregation of the mass-flow during transport. The dominant scale lengths can be used as a proxy for strain history, which can improve understanding of post-failure dynamics and emplacement of subacqueous mass-movements, important for constraining the geohazard potential from future slope failure.

scholarly journals SEISMIC STRATIGRAPHY OF THE EOCENE–LOWER OLIGOCENE IN THE URUGUAYAN CONTINENTAL MARGIN / ESTRATIGRAFIA SÍSMICA DO EOCENO AO OLIGOCENO INFERIOR NA MARGEM CONTINENTAL URUGUAIA

2018 ◽  
Vol 3 (4) ◽  
pp. 290-306 ◽  
Author(s):  
Belén Viera Honegger ◽  
Ethel Morales ◽  
Matias Soto ◽  
Bruno Conti
Keyword(s):  
Continental Margin ◽  
Sedimentary Basins ◽  
Seismic Facies ◽  
Depositional Sequences ◽  
Normal Regression ◽  
Depositional Systems ◽  
Seismic Sections ◽  
Pelotas Basin ◽  
Definition Of ◽  
Stacking Patterns

The Uruguayan continental margin was generated following the fragmentation of the Gondwana supercontinent and the subsequent opening of South Atlantic Ocean. It constitutes an extensive sedimentation area in which three sedimentary basins can be found: the Punta del Este Basin, the southernmost portion of the Pelotas Basin, and the poorly defined Oriental del Plata Basin. The aim of this work was the identification and characterization of the different seismic units (seismic facies, systems tracts, depositional sequences) for the sedimentary interval assigned to the Eocene in the Uruguayan continental margin. Sequence stratigraphy was used as a basin analysis method for this purpose, using a database that consisted of approximately 10,000 kilometers of 2D seismic sections, acquired in exploratory surveys in 2007 and 2008. The workflow included the recognition of stacking patterns and/or stratal terminations, the definition of genetically significant stratigraphic surfaces and, based on these, the identification of systems tracts and depositional sequences. Three depositional sequences were identified in the studied sedimentary interval. The basal sequence is composed of four depositional systems tracts, including falling stage, normal regression (lowstand and highstand) and transgressive deposits. The intermediate sequence only preserves lowstand normal regression deposits. The third sequence is composed by three depositional systems tracts, including lowstand, transgressive and falling stage deposits. ResumoA margem continental uruguaia foi gerada após a fragmentação do supercontinente Gondwana e a subsequente abertura do Oceano Atlântico Sul. Constitui uma extensa área de sedimentação em três bacias sedimentares: a bacia de Punta del Este, a porção mais ao sul da Bacia de Pelotas e a Bacia Oriental del Plata, pouco definida. O objetivo deste trabalho foi a identificação e caracterização das diferentes unidades sísmicas (fácies sísmicas, tratos de sistemas, seqüências deposicionais) para o intervalo sedimentar atribuído ao Eoceno na margem continental uruguaia. Com este objetivo, utilizou-se a estratigrafia de seqüencias como método de análise de bacias, tendo-se utilizado um banco de dados constituído por aproximadamente 10.000 km de seções sísmicas 2D, adquiridas em pesquisas exploratórias em 2007 e 2008. O trabalho incluiu o reconhecimento de padrões de empilhamento e/ou terminações estratais, a definição de superfícies estratigráficas geneticamente significativas, tendo-se efetuado com base nelas, a identificação de tratos de sistemas e seqüências deposicionais. Três seqüências deposicionais foram identificadas no intervalo sedimentar estudado. A seqüência basal é composta por quatro tratos de sistemas deposicionais, incluindo a fase de abaixamento do nível do mar, a regressão normal e depósitos transgressivos. A sequência intermediária apenas preserva os depósitos de regressão normais de nível de mar baixo. A terceira seqüência é composta por três tratos de sistemas deposicionais, incluindo depósitos de nível de mar baixo, transgressivos e de abaixamento do nível do mar.

scholarly journals Core-log-seismic integration in metamorphic rocks at the ICDP drilling project COSC-1, Sweden

2021 ◽  
Author(s):  
Judith Elger ◽  
Christian Berndt ◽  
Felix Kästner ◽  
Simona Pierdominici ◽  
Jochem Kück ◽  
...  
Keyword(s):  
Gamma Ray ◽  
Sedimentary Basins ◽  
Shear Zones ◽  
Seismic Profile ◽  
Passive Margin ◽  
Three Dimensions ◽  
Metamorphic Rocks ◽  
Metamorphic Overprint ◽  
Nappe Complex ◽  
Seve Nappe Complex

<p>Continental collision causes deformation in the crust along shear zones. However, the physical and chemical conditions at which these zones operate and the deformation processes that enable up to hundreds of km of tectonic transport are still unclear because of the depth at which they occur and the challenges in imaging them. Ancient exhumed collision zones allow us to investigate these processes much better, for example at the COSC-1 borehole in the central Scandinavian Caledonides. This study combines data from the COSC-1 borehole, such as downhole logging and zero-offset vertical seismic profile data, with 2D and 3D seismic measurements to provide constraints on the spatial lithological and textural configuration of the Seve Nappe Complex. This is one of the few studies that shows that core-log-seismic integration in metamorphic rocks allows to identify the spatial distribution of major lithological units, even though the methodology was originally developed for sedimentary basins in the hydrocarbon industry. Especially gamma ray logs in combination with density data are powerful tools to distinguish between mafic and felsic lithologies in log-core correlation. Reflections in the Seve Nappe Complex are not as distinct as in greater depths but continuous, and our results indicate that they are primarily caused by compositional rather than textural changes. Several of the reflections can be linked to magmatic intrusions, which have been metamorphically overprinted. Their setting indicates that the Seve Nappe Complex consists of the remnants of a volcanic continental margin. It appears that in spite of the metamorphic overprint around 417+/-9 Ma, the original configuration of the volcanic passive margin is partly preserved in the Seve Nappe Complex and that it outlasted continent-continent collision, including the nappe emplacement. Thus, an integration of borehole and three-dimensional geophysical data can image lithological changes that can then be extrapolated in three dimensions to arrive at a better understanding of the composition and geometry at mid-crustal levels. Furthermore, our results suggest that ductile-deformed middle crustal reflectivity is primarily a function of pre-orogenic lithological variations which has to be considered when deciphering mountain building processes.</p>

Tectono-stratigraphic evolution of the Aptian Pre-Salt of the onshore Espírito Santo Basin, SE Brazil, an example of proximal passive margin sag basin

2020 ◽  
Author(s):  
Francyne Bochi do Amarante ◽  
André Basso Schilling ◽  
Juliano Kuchle ◽  
David Iacopini ◽  
Claiton Marlon dos Santos Scherer ◽  
...  
Keyword(s):  
Gamma Ray ◽  
Passive Margin ◽  
Seismic Facies ◽  
Rift System ◽  
Facies Association ◽  
Base Level ◽  
Coastal Waves ◽  
Se Brazil ◽  
Facies Associations ◽  
3D Volume

<p>The Espírito Santo Basin is part of the Brazilian rift system basins, formed by the break-up of the Supercontinent Gondwana and subsequent opening of the South Atlantic Ocean. The Aptian sedimentary succession of the basin is named Mucuri Member, lower unit of Mariricu Formation, and is contemporary to the pre-salt main carbonate reservoirs. Proximal deposition consists mostly of clastic sediments, interpreted as fluvial and coastal systems in the margins of a wide lake, which synchronously accumulated carbonates to the distal portions. The economic interest for oil is centered on the distal carbonates, thus the proximal sections lack detailed studies. The main objective of this study is the tectono-stratigraphic analysis of the marginal Mucuri Member. Leading methodology is seismic stratigraphy based on 220 2D lines and 1 3D volume, coupled with petrophysical and lithological analysis of 103 well log data and 5 cored wells. The combined analysis of seismic and lithological parameters resulted in the individualization of four seismic facies, which correspond to the predominance of one or two amongst five facies associations interpreted in cored wells. Seismic facies (SF) 1 is predominantly composed of offshore and lower shoreface successions; SF 2 is characterized by a dominance of poorly confined fluvial channels facies association; SF 3 records the interaction between fluvial and coastal successions composing mound-like structures, and is interpreted as wave-dominated deltaic facies association; SF 4 corresponds to sandspits structures and is restricted to regions where the coastal waves interact with basement highs. Four seismostratigraphic units were identified (named, from the base upwards: MUC1, MUC2, MUC3 and MUC4), delimited by three subparallel horizons. Unit-bounding reflectors coincide with gamma ray maxima or minima representing shales or anhydrites, respectively, deposited in deep water environments. The Mucuri Member records an enlargement in depositional area from the base upwards witnessing an overall lacustrine base level rise during deposition. The geometry of the depositional area during MUC1 and MUC2 was conditioned by the paleorelief of the preceding rift basins. MUC3 and MUC4 seismic units record a decrease in thickness as remnant topography was gradually filled; both units transcended and draped the half-grabens. The Early Cretaceous Mucuri Member composes the beginning of the post-rift sequence of Espírito Santo Basin, marked by the onset of thermal subsidence and cessation of mechanical subsidence.</p>

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