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.

Shear margin moraine, mass transport deposits and soft beds revealed by high-resolution P-Cable three-dimensional seismic data in the Hoop area, Barents Sea

2018 ◽  
Vol 477 (1) ◽  
pp. 537-548 ◽  
Author(s):  
Benjamin Bellwald ◽  
Sverre Planke
Keyword(s):  
High Resolution ◽  
Mass Transport ◽  
Seismic Data ◽  
Slope Failure ◽  
Barents Sea ◽  
3D Seismic ◽  
Seismic Reflection Data ◽  
Shallow Subsurface ◽  
Mass Transport Deposits ◽  
Amplitude Reflection

AbstractHigh-resolution seismic data are powerful tools that can help the offshore industries to better understand the nature of the shallow subsurface and plan the development of vulnerable infrastructure. Submarine mass movements and shallow gas are among the most significant geohazards in petroleum prospecting areas. A variety of high-resolution geophysical datasets collected in the Barents Sea have significantly improved our knowledge of the shallow subsurface in recent decades. Here we use a c. 200 km2 high-resolution P-Cable 3D seismic cube from the Hoop area, SW Barents Sea, to study a 20–65 m thick glacial package between the seabed and the Upper Regional Unconformity (URU) horizons. Intra-glacial reflections, not visible in conventional seismic reflection data, are well imaged. These reflections have been mapped in detail to better understand the glacial deposits and to assess their impact on seabed installations. A shear margin moraine, mass transport deposits and thin soft beds are examples of distinct units only resolvable in the P-Cable 3D seismic data. The top of the shear margin moraine is characterized by a positive amplitude reflection incised by glacial ploughmarks. Sedimentary slide wedges and shear bands are characteristic sedimentary features of the moraine. A soft reflection locally draping the URU is interpreted as a coarser grained turbidite bed related to slope failure along the moraine. The bed is possibly filled with gas. Alternatively, this negative amplitude reflection represents a thin, soft bed above the URU. This study shows that P-Cable 3D data can be used successfully to identify and map the external and internal structures of ice stream shear margin moraines and that this knowledge is useful for site-survey investigations.

scholarly journals Thrust Faults Promoted Hydrocarbon Leakage at the Compressional Zone of Fine-Grained Mass-Transport Deposits

2021 ◽  
Vol 9 ◽  
Author(s):  
Qiliang Sun ◽  
Xinong Xie ◽  
Shiguo Wu ◽  
Guorui Yin
Keyword(s):  
Fluid Flow ◽  
Mass Transport ◽  
Northern South China Sea ◽  
Coarse Grained ◽  
Thrust Faults ◽  
Borehole Data ◽  
Fine Grained ◽  
Hydrocarbon Reservoir ◽  
Effective Seal ◽  
Mass Transport Deposits

Fine-grained mass-transport deposits (MTDs), especially their compressional toe zones, are traditionally considered as effective seal in constraining the vertical fluid migration underneath. However, this study documents thrust faults at the compressional toe zone of fine-grained MTDs that could disaggregate the seal competence and promote vertical fluid flow. The investigated MTD referred to as MTD-a lies directly over a large hydrocarbon reservoir that is located within the Central Canyon of northern South China Sea, which is examined by using high-resolution 3D seismic and borehole data. Thrust faults and irregular blocks composed of coarse-grained sandstones are observed in the compressional zone of the MTD-a’s toe. More importantly, seismic evidence (e.g., enhanced seismic reflections) suggests that a large amount of hydrocarbons from the underlying reservoir penetrated through the MTD-a along these thrust faults and charged into the coarse-grained sandstone blocks. This clear evidence of thrust faults compromising the MTD’s seal effectiveness and thus facilitating the vertical fluid flow through the non-permeable strata demonstrate the importance of reassessing the seal capacity of MTD.

Late Cenozoic architecture of the St. Pierre Slope

2005 ◽  
Vol 42 (11) ◽  
pp. 1987-2000 ◽  
Author(s):  
David JW Piper ◽  
Adam WA Macdonald ◽  
Stephen Ingram ◽  
Graham L Williams ◽  
Curtis McCall
Keyword(s):  
Mass Transport ◽  
Seismic Reflection ◽  
Failure Surface ◽  
Late Cenozoic ◽  
Grand Banks ◽  
Age Model ◽  
Seismic Reflection Profiles ◽  
Mass Transport Deposits ◽  
Bermuda Rise ◽  
Upper Slope

The late Cenozoic seismic stratigraphy of the continental slope south of western Newfoundland is interpreted using new seismic reflection profiles. New Miocene–Pliocene biostratigraphic (palynology) age determinations on the Hermine E-94 well on the northwestern Grand Banks of Newfoundland are correlated to the study area. The Quaternary section of St. Pierre Slope is disrupted by numerous failure scarps and mass-transport deposits, but correlation from the mid- slope to the continental rise is achieved using major mass-transport deposits as markers. On the upper slope, stacked downslope-thinning wedges of acoustically incoherent sediment are interpreted as till deposits of mid- to late Pleistocene age. Sedi mentation rates in the youngest part of the succession are estimated from a 30 ka radiocarbon date 25 m below the horizon of the youngest till tongue, which is exposed on a 60 m deep failure surface. Extrapolation of sedimentation rates and comparison with dated sections on the J-Anomaly Ridge and Bermuda Rise provides a consistent interpreted age model for the till tongues that corresponds to marine isotope stages 2, 4, 6, 8, 10, and 12.

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.

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