From mechanical modeling to seismic imaging of faults: A synthetic workflow to study the impact of faults on seismic

Botter, Charlotte; Cardozo, Néstor; Hardy, Stuart; Lecomte, Isabelle; Escalona, Alejandro

doi:10.1016/j.marpetgeo.2014.05.013

Cited by 80 publications

(61 citation statements)

References 82 publications

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“…They are typically assessed through the use of angle of repose and/or unconfined/confined biaxial numerical tests (cf. Oger et al, ; Finch et al, ; Holohan et al, ; Botter et al, ). Using such tests, the frictional‐cohesive discrete elements used here have been found to have a bulk coefficient of friction ( µ ) of c. 0.70 (internal angle of friction [ ø ] of c. 35°) and to have a cohesion of c. 2.8 MPa.…”

Section: Methodsmentioning

confidence: 99%

Discrete element modelling of extensional, growth, fault‐propagation folds

Hardy

2019

Basin Research

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Extensional fault‐propagation folds are now recognised as being an important part of basin structure and development. They have a very distinctive expression, often presenting an upward‐widening monocline, which is subsequently breached by an underlying, propagating fault. Growth strata, if present, are thought to provide a crucial insight into the manner in which such structures grow in space and time. However, interpreting their stratigraphic signal is neither straightforward nor unique. Both analogue and numerical models can provide some insight into fold growth. In particular, the trishear kinematic model has been widely adopted to explain many aspects of the evolution and geometry of such fault‐propagation folds. However, in some cases the materials/rheologies used to represent the cover do not reproduce the key geometric/stratigraphic features of such folds seen in nature. This appears to arise from such studies not addressing adequately the very heterogenous mechanical stratigraphy seen in many sedimentary covers. In particular, flexural slip between beds/layers is often not explicitly modelled but, paradoxically, it appears to be an important deformation mechanism operative in such settings. Here, I present a 2D discrete element model of extensional fault‐propagation folding which explicitly includes flexural slip between predefined sedimentary units or layers in the cover. The model also includes growth strata and shows how they may reflect the various evolutionary stages of fold and fault growth. When flexural slip is included in the modelling scheme, the resultant breached monoclines and their growth strata are strikingly similar to some of those seen in nature. Results are also compared with those obtained using simple, homogeneous, frictional‐cohesive and elastic cover materials. Both un‐lithified and lithified growth strata are considered and clearly show that, rather than just being passive recorders of structural evolution, growth strata can themselves have an important effect on fault‐related fold growth. Implications for the evolution of and strain within, the resultant growth structures are discussed. A final focus of this study is the relationship that trishear might have with the upward‐widening zone of flexural slip activation away from a fault tip singularity.

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Section: Methodsmentioning

confidence: 99%

Discrete element modelling of extensional, growth, fault‐propagation folds

Hardy

2019

Basin Research

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“…However, one disadvantage of the technique lies in the necessary calibration of micro‐particle parameters to emergent physical properties (cf. Botter et al., ; Egholm et al., ). In a similar manner, the sensitivity of models results to subtle initial differences in, for example, assembly packing is well‐known (cf.…”

Section: Methodsmentioning

confidence: 99%

“…They are typically assessed through the use of angle of repose and/or unconfined/confined biaxial numerical tests (cf. Botter et al., ; Finch et al. ; Holohan, Schopfer, & Walsh, ; Oger, Savage, Corriveau, & Sayed, ).…”

Section: Model Parameters Setup and Boundary Conditionsmentioning

confidence: 99%

Novel discrete element modelling of Gilbert‐type delta formation in an active tectonic setting—first results

Hardy

2018

Basin Research

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Gilbert deltas are now recognised as an important stratigraphic component of many extensional basins. They are remarkable due to their coarse‐grained nature, large size and steep foresets (up to 30–35°) and may exhibit a variety of slope instability features (faulting, slump scars, avalanching, etc.). They are also often closely related to major, basin‐margin normal faults. There has been considerable research interest in Gilbert deltas, partly due to their economic significance as stratigraphic traps for hydrocarbons but also due to their sensitivity to relative base level changes, giving them an important role in basin analysis. In addition to field studies, numerical modelling has also been used to simulate such deltas, with some success. However, until now, such studies have typically employed continuum numerical techniques where the basic data elements created by simulations are stratigraphic volumes or timelines and the sediments themselves have no internal properties per se and merely represent areas/volumes of introduced coarse‐grained, clastic and sedimentary material. Faulting or folding (if present) are imposed externally and do not develop (naturally) within the modelled delta body itself. Here, I present first results from a novel 2D numerical model which simulates coarse‐grained (Gilbert‐type) deltaic sedimentation in an active extensional tectonic setting undergoing a relative base level rise. Sediment is introduced as packages of discrete elements which are deposited beneath sea level, from the shoreline, upon a pre‐existing basin or delta. These elements are placed carefully and then allowed to settle onto the system. The elements representing the coarse‐grained, deltaic sediments can have an intrinsic coefficient of friction, cohesion or other material properties appropriate to the system being considered. The spatial resolution of the modelling is of the order of 15 m and topsets, foresets, bottomsets, faults, slumps and collapse structures all form naturally in the modelled system. Examples of deltas developing as a result of sediment supply from both the footwall and hanging‐wall of a normal fault, and subject to changes in fault slip rate are presented. Implications of the modelling approach, and its application and utility in basin research, are discussed.

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“…The current analog model of Figure 13 lacks, however, realistic elastic properties. Figure 14 shows 3D numerical modeling of fault zones (Botter et al, 2014a(Botter et al, , 2014b, using the 3D spatial convolution to generate seismic cubes from such complex and detailed 3D scattering structures. Going from outcrop to reservoir models prior to seismic modeling is also a possibility (Rotevatn and Fossen, 2011;Botter et al, 2015), provided that we do not lose too much of the lateral variability due to large pillars, as earlier mentioned.…”

Section: Interpretation / November 2015 Sac81mentioning

confidence: 99%

Ray-based seismic modeling of geologic models: Understanding and analyzing seismic images efficiently

et al. 2015

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Often, interpreters only have access to seismic sections and, at times, well data, when making an interpretation of structures and depositional features in the subsurface. The validity of the final interpretation is based on how well the seismic data are able to reproduce the actual geology, and seismic modeling can help constrain that. Ideally, modeling should create complete seismograms, which is often best achieved by finite-difference modeling with postprocessing to produce synthetic seismic sections for comparison purposes. Such extensive modeling is, however, not routinely affordable. A far more efficient option, using the simpler 1D convolution model with reflectivity logs extracted along verticals in velocity models, generates poor modeling results when lateral velocity variations are expected. A third and intermediate option is to use the various ray-based approaches available, which are efficient and flexible. However, standard ray methods, such as the normal-incidence point for unmigrated poststack sections or image rays for simulating time-migrated poststack results, cannot deal with complex and detailed targets, and will not reproduce the realistic (3D) resolution effects of seismic imaging. Nevertheless, ray methods can also be used to estimate 3D spatial prestack convolution operators, so-called point-spread functions. These are functions of the survey, velocity model, and wavelet, among others, and therefore they include 3D angle-dependent illumination and resolution effects. Prestack depth migration images are thus rapidly simulated by spatial convolution with detailed 3D reflectivity models, which goes far beyond the limits of 1D convolution modeling. This 3D convolution modeling should allow geologists to better assess their interpretations and draw more definitive conclusions.

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From mechanical modeling to seismic imaging of faults: A synthetic workflow to study the impact of faults on seismic

Cited by 80 publications

References 82 publications

Discrete element modelling of extensional, growth, fault‐propagation folds

Discrete element modelling of extensional, growth, fault‐propagation folds

Novel discrete element modelling of Gilbert‐type delta formation in an active tectonic setting—first results

Ray-based seismic modeling of geologic models: Understanding and analyzing seismic images efficiently

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