Seismic expression of salt tectonics in the Sab’atayn Basin, onshore Yemen

2014 ◽  
Vol 2 (4) ◽  
pp. SM91-SM100 ◽  
Author(s):  
Gabor Tari ◽  
Rudi Dellmour ◽  
Emma Rodgers ◽  
Shaista Sultan ◽  
Abdo Al Atabi ◽  
...  
Keyword(s):  
Seismic Data ◽  
Strong Correlation ◽  
Seismic Reflection ◽  
Upper Jurassic ◽  
Salt Tectonics ◽  
3D Seismic ◽  
Flip Flop ◽  
Well Data ◽  
Tectonic Features ◽  
3D Seismic Data

A variety of distinct salt tectonic features are present in the Sab’atayn Basin of western Yemen. Based on the interpretation of 2D/3D seismic data and exploration wells in the central part of the basin, an Upper Jurassic evaporite unit produced numerous salt rollers, salt pillows, reactive, flip-flop, and falling diapirs. Halokinetics began as soon as the early Cretaceous, within just a few million years after the deposition of the Tithonian Sab’atayn evaporite sequence. The significant proportions of nonevaporite lithologies within the “salt” made the seismic interpretation of the salt features challenging. The evaporite sequence had been described by most as a syn-rift unit and therefore a strong correlation was assumed between the subsalt syn-rift basement architecture and the overlying diapirs and other salt-related features. However, seismic reflection and well data revealed a nonsystematic relationship between the salt diapirs and the subsalt basement highs. This observation has very important implications for the subsalt fractured basement play in the Sab’atayn Basin.

Extensive, Gas-charged Quaternary Sand Accumulations of the Northern North Sea and North Sea Fan

2020 ◽  
Author(s):  
Benjamin Bellwald ◽  
Sverre Planke ◽  
Sunil Vadakkepuliyambatta ◽  
Stefan Buenz ◽  
Christine Batchelor ◽  
...  
Keyword(s):  
North Sea ◽  
Seismic Data ◽  
Data Sets ◽  
3D Seismic ◽  
Fine Grained ◽  
The North ◽  
Northern North Sea ◽  
Well Data ◽  
Sea Fan ◽  
3D Seismic Data

<p>Sediments deposited by marine-based ice sheets are dominantly fine-grained glacial muds, which are commonly known for their sealing properties for migrating fluids. However, the Peon and Aviat hydrocarbon discoveries in the North Sea show that coarse-grained glacial sands can occur over large areas in formerly glaciated continental shelves. In this study, we use conventional and high-resolution 2D and 3D seismic data combined with well information to present new models for large-scale fluid accumulations within the shallow subsurface of the Norwegian Continental Shelf. The data include 48,000 km<sup>2</sup> of high-quality 3D seismic data and 150 km<sup>2</sup> of high-resolution P-Cable 3D seismic data, with a vertical resolution of 2 m and a horizontal resolution of 6 to 10 m in these data sets. We conducted horizon picking, gridding and attribute extractions as well as seismic geomorphological interpretation, and integrated the results obtained from the seismic interpretation with existing well data.</p><p>The thicknesses of the Quaternary deposits vary from hundreds of meters of subglacial till in the Northern North Sea to several kilometers of glacigenic sediments in the North Sea Fan. Gas-charged, sandy accumulations are characterized by phase-reserved reflections with anomalously high amplitudes in the seismic data as well as density and velocity decreases in the well data. Extensive (>10 km<sup>2</sup>) Quaternary sand accumulations within this package include (i) glacial sands in an ice-marginal outwash fan, sealed by stiff glacial tills deposited by repeated glaciations (the Peon discovery in the Northern North Sea), (ii) sandy channel-levee systems sealed by fine-grained mud within sequences of glacigenic debris flows, formed during shelf-edge glaciations, (iii) fine-grained glacimarine sands of contouritic origin sealed by gas hydrates, and (iv) remobilized oozes above large evacuation craters and sealed by megaslides and glacial muds. The development of the Fennoscandian Ice Sheet resulted in a rich variety of depositional environments with frequently changing types and patterns of glacial sedimentation. Extensive new 3D seismic data sets are crucial to correctly interpret glacial processes and to analyze the grain sizes of the related deposits. Furthermore, these data sets allow the identification of localized extensive fluid accumulations within the Quaternary succession and distinguish stratigraphic levels favorable for fluid accumulations from layers acting as fluid barriers.</p>

Salt in the Vulcan sub-basin, NW Australia: observations from high-quality 3D seismic data and implications for palaeogeography

2021 ◽  
Vol 61 (2) ◽  
pp. 684
Author(s):  
Simon Molyneux ◽  
Stephen Doyle
Keyword(s):  
Seismic Data ◽  
Spatiotemporal Distribution ◽  
3D Seismic ◽  
High Quality ◽  
Regional Tectonic ◽  
Tectonic Features ◽  
First Time ◽  
3D Seismic Data ◽  
Nw Australia

The Vulcan sub-basin is one of the few places in Australia where tectonic features (i.e. diapirs) associated with a mobile substrate can be found. In this presentation one of these features, the Paqualin diapir, and its environs will be described and discussed using the new regional NOVAR MC3D prestack depth migrated seismic dataset. The extent of the NOVAR MC3D seismic dataset makes it possible, for the first time, to integrate the observation of c. 600m of interbedded halite and anhydrite in the Paqualin-1 well, local fault geometries indicative of the movement of a mobile layer and regional tectonic features consistent with the presence of a mobile substrate. In this presentation the observations will be integrated with global analogues, regional palaeogeographic interpretations to refine models for the origin and spatiotemporal distribution of mobile layers in the Vulcan sub-basin.

Detailed Geomorphology of Cold Seeps Associated with a Buried Salt Diapir, Offshore Nova Scotia, Canada

2020 ◽  
Author(s):  
Calvin Campbell ◽  
Alexandre Normandeau ◽  
Paul Fraser ◽  
Adam MacDonald
Keyword(s):  
Nova Scotia ◽  
Seismic Data ◽  
Seismic Reflection ◽  
Cold Seep ◽  
Salt Diapir ◽  
Cold Seeps ◽  
3D Seismic ◽  
Seismic Reflection Data ◽  
Reflection Data ◽  
3D Seismic Data

<p>Cold seeps occur where fluids, such as hydrocarbons, migrate from depth and escape at the seabed. They are relatively common features in petroleum basins around the world. Cold seeps often host unique biological communities and are a potential geological hazard as they can indicate excess pore fluid pressures in shallow sediments. In addition, they can provide critical information about fluid migration pathways and fluid source. This study presents the detailed geomorphology and seismic stratigraphy of recently discovered cold seeps in 2700 metres water depth offshore Nova Scotia, Canada. </p><p>Petroleum industry 3D seismic reflection data, high-resolution single channel G.I. gun and sparker seismic reflection data, Autonomous Underwater Vehicle (AUV) sidescan, swath bathymetry, and sub-bottom profiler data were used to investigate the geomorphology of the cold seep and surrounding seabed. Piston core samples and seabed photography were also acquired in the study area.</p><p>The geomorphology in the study area is dominated by the seafloor expression of a salt diapir (L. Triassic to E. Jurassic). Despite being buried by ~1700 m of Cretaceous to Holocene sediment, the diapir forms an oblong mound, 10 km long by 5 km wide that rises 200 m above the surrounding seabed. Two major orthogonal faults are apparent on the seabed that cut the mound along its major and minor axes. Several crestal faults are imaged in the 3D seismic data but do not have a seabed expression. AUV data acquired over the crest of the diapir reveal a 500 m by 200 m fissure on the western flank of the diapir. The fissure is composed of a blocky central zone along its axis, and radiating “cracks” that show backscatter variation, possibly indicating recent fluid expulsion. Integration of the AUV data with the 3D seismic data show that the fissure is fed by a vertical chimney that intersects a bottom simulating reflection above the diapir. Remarkably, the chimney does not appear to be related to any of the sub-vertical crestal faults. Another seep occurs on the eastern flank of the diapir crest and, in contrast, coincides with a crestal fault. There is also evidence for mass wasting down-dip from the fault. Core samples recovered from the second seep contained gas hydrate. In both cases, the cold seeps present as very subtle features on the 3D seismic reflection data and are only positively identified in the AUV datasets. This study shows that conventional surface-acquired acoustic data are potentially insufficient for detecting cold seep morphologies in deep-water settings.</p>

scholarly journals Enhancing trap and fault seal analyses by integrating observations from HR3D seismic data with well logs and conventional 3D seismic data, Texas inner shelf

2019 ◽  
Vol 496 (1) ◽  
pp. 253-279 ◽  
Author(s):  
Johnathon L. Osmond ◽  
Timothy A. Meckel
Keyword(s):  
Seismic Data ◽  
Analytical Techniques ◽  
3D Seismic ◽  
Inner Shelf ◽  
Geological Interpretation ◽  
Industry Standard ◽  
3D Data ◽  
Well Data ◽  
Gas Chimneys ◽  
3D Seismic Data

AbstractAn understanding of trap and fault seal quality is critical for assessing hydrocarbon prospectivity. To achieve this, modern analytical techniques leverage well data and conventional industry-standard 3D seismic data to evaluate the trap, and any faults displacing the reservoir and top seal intervals. Above all, geological interpretation provides the framework of trap and fault seal analyses, but can be hindered by the data resolution, quality and acquisition style of the conventional seismic data. Furthermore, limiting the analysis to only the petroleum system at depth may lead to erroneous perceptions because interpreting overburden features, such as shallow faults or gas chimneys, can provide valuable observations with respect to container performance, and can to help validate trap and fault seal predictions. A supplement to conventional 3D data are high-resolution 3D seismic (HR3D) data, which provide detailed images of the overburden geology. This study utilizes an HR3D seismic volume in the San Luis Pass area of the Texas inner shelf, where shallow fault tips and a sizeable gas chimney are interpreted over an unsuccessful hydrocarbon prospect. Static post-drill fault seal and trap analyses suggest that the primary fault displacing the structural closure could have withheld columns of gas c. 100 m high, but disagree with our HR3D seismic interpretations and dry-well analyses. From our results, we hypothesize that tertiary gas migration through fault conduits reduced the hydrocarbon column in the prospective Early Miocene reservoir, and may have resulted from continued movement along the intersecting faults. Overall, this study reinforces the importance of understanding the overburden geology and geohistory of faulted prospects, and demonstrates the utility of pre-drill HR3D acquisition when conducting trap and fault seal analyses.

New insights into the kinematics and timing of superimposed rifting events through integration of offshore data, onshore fieldwork and U-Pb geochronology: Inner Moray Firth Basin, Scotland

2020 ◽  
Author(s):  
Alexandra Tamas ◽  
Robert Holdsworth ◽  
John Underhill ◽  
Kenneth McCaffrey ◽  
Eddie Dempsey ◽  
...  
Keyword(s):  
Seismic Data ◽  
Upper Jurassic ◽  
Fault Reactivation ◽  
Full Potential ◽  
Rift Basin ◽  
3D Seismic ◽  
Seismic Reflection Data ◽  
Moray Firth ◽  
Orcadian Basin ◽  
3D Seismic Data

<p>Keywords: inherited structures, fault reactivation, U-Pb geochronology</p><p>The E-W striking Inner Moray Firth Basin (IMFB) lies in the western part of the North Sea trilete rift system formed mainly in the Upper Jurassic. The IMFB has experienced a long history of superimposed rifting with plenty of uplift and fault reactivation during Cenozoic. The basin is overlying the Caledonian basement, the pre-existing Devonian-Carboniferous (Orcadian Basin) and a regionally developed Permo-Triassic basin. The potential influence of older structures related to the Orcadian Basin on the kinematics of later basin opening has received little attention, partly due to the poor resolution of seismic reflection data at depth or sparse well data.</p><p>By integrating onshore fieldwork with the interpretation of 2D and 3D seismic data and U-Pb geochronology of syndeformationally grown calcite we provide new insights into the kinematic opening of the basin as well as the role of pre-existing Devonian-Carboniferous (Orcadian) basin structures.</p><p>The Jurassic opening of the rift basin is known to be associated with major NE-SW trending faults. New detailed mapping of offshore 3D seismic data revealed that at a smaller scale en-echelon E-W to NE-SW trending faults, en-echelon N-S to NNE-SSW and NW-SE fault arrays coexist. This suggests an oblique-sinistral component associated with the major NE-SW rift basin trends. This correlates with onshore findings, which suggest that the inherited Orcadian fault systems (mainly N-S to NE-SW) have been dextrally reactivated. Sinistral WNW-SSE to NW-SE striking faults and associated transtensional folds are also present in the Devonian rocks. This later deformation is consistently associated with calcite mineralization (e.g. slickenfibers, calcite tensile veins or Riedel shear fractures). New U-Pb dating of the calcite mineralization, related to the reactivated faults, shows that the age of fault reactivation is 153 ± 0.68 Ma (Upper Jurassic).</p><p>The integration of fieldwork with subsurface interpretations and absolute dating techniques has provided better constraints on superimposed basin development, as well as explaining complexities that have hitherto been ignored. This can reduce subsurface uncertainties regarding the structural evolution of the basin and unlock the full potential of the area and significantly enhance future exploration programs.</p>

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